U.S. patent application number 14/335284 was filed with the patent office on 2014-11-27 for roofing products containing phase change materials.
The applicant listed for this patent is Keith C. Hong, Ming Liang Shiao. Invention is credited to Keith C. Hong, Ming Liang Shiao.
Application Number | 20140349072 14/335284 |
Document ID | / |
Family ID | 38919434 |
Filed Date | 2014-11-27 |
United States Patent
Application |
20140349072 |
Kind Code |
A1 |
Hong; Keith C. ; et
al. |
November 27, 2014 |
Roofing Products Containing Phase Change Materials
Abstract
A solar heat responsive roofing material includes a continuous
phase and dispersed discontinuous phase having a phase transition
at a temperature between about 50 degrees Celsius and about 95
degrees Celsius.
Inventors: |
Hong; Keith C.; (Lititz,
PA) ; Shiao; Ming Liang; (Collegeville, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hong; Keith C.
Shiao; Ming Liang |
Lititz
Collegeville |
PA
PA |
US
US |
|
|
Family ID: |
38919434 |
Appl. No.: |
14/335284 |
Filed: |
July 18, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11769530 |
Jun 27, 2007 |
|
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14335284 |
|
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60806777 |
Jul 8, 2006 |
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Current U.S.
Class: |
428/147 |
Current CPC
Class: |
Y10T 428/24372 20150115;
Y10T 428/24405 20150115; E04D 2001/005 20130101; E04D 1/22
20130101; E04D 1/20 20130101; E04D 5/12 20130101; E04D 13/00
20130101; Y02E 70/30 20130101; Y10T 428/24355 20150115; F28D 20/023
20130101; Y02E 60/14 20130101; Y02E 60/145 20130101 |
Class at
Publication: |
428/147 |
International
Class: |
E04D 1/22 20060101
E04D001/22; E04D 1/20 20060101 E04D001/20; E04D 13/00 20060101
E04D013/00 |
Claims
1. A solar heat responsive roofing material comprising: a) a
continuous phase; and b) a discontinuous phase dispersed in the
continuous phase, the discontinuous phase having a phase transition
at a temperature between about 50 degrees Celsius and about 95
degrees Celsius, the discontinuous phase comprising at least one
thermoplastic polymer
2. Roofing material according to claim 1 wherein the phase
transition temperature is between about 60 degrees Celsius and
about 85 degrees Celsius.
3. Roofing material according to claim 1 wherein the discontinuous
phase has a phase transition enthalpy of at least about 100
kilojoules per kg.
4. Roofing material according to claim 1 wherein the discontinuous
phase constitutes at least ten percent by weight of the roofing
material.
5. Roofing material according to claim 1 wherein the thermoplastic
polymer is selected from the group consisting of poly(vinyl ethyl
ether), poly(vinyl n-butyl ether) and polychloroprene.
6. Roofing material according to claim 1 wherein the roof includes
a base sheet having a bituminous coating, the continuous phase
comprising the bituminous coating.
7. Roofing material according to claim 1 wherein the discontinuous
phase includes a plurality of fibers comprising phase change
material.
8. A solar heat-responsive roofing material comprising: a) a
bituminous base sheet; and b) a plurality of roofing granules, the
roofing granules including a latent-heat storage material having a
phase transition at a temperature between about 50 degrees Celsius
and about 95 degrees Celsius, the latent-heat storage material
comprising at least one thermoplastic polymer.
9. A solar heat-responsive roofing material according to claim 15
wherein the phase transition temperature is between about 60
degrees Celsius and about 85 degrees Celsius.
10. A solar heat-responsive roofing material according to claim 8
wherein the heat storage material has a phase transition enthalpy
of at least 100 kilojoules per kg.
11. A solar heat-responsive roofing material according to claim 8
wherein the heat storage material constitutes at least ten percent
by weight of the roofing material.
12. A solar heat-responsive roofing material according to claim 8
wherein the thermoplastic polymer is selected from the group
consisting of poly(vinyl ethyl ether), poly(vinyl n-butyl ether)
and polychloroprene.
13. A solar heat-responsive roofing material according to claim 8
wherein the heat storage material includes a plurality of fibers
comprising phase change material.
14. A solar heat-responsive roofing material comprising: a) at
least one solar-heat reflective material; and b) at least one
latent-heat storage material, the at least one latent-heat storage
material having a phase transition at a temperature between about
50 degrees Celsius and about 95 degrees Celsius, the at least one
latent-heat storage material comprising a thermoplastic polymer,
wherein the roofing material includes a continuous phase, and a
discontinuous phase dispersed in the continuous phase, the
discontinuous phase including the latent-heat storage material.
15. A solar heat-responsive roofing material according to claim 14
wherein the phase transition temperature is between about 60
degrees Celsius and about 85 degrees Celsius.
16. A solar heat-responsive roofing material according to claim 14
wherein the latent-heat storage material has a phase transition
enthalpy of at least about 100 kilojoules per kg.
17. A solar heat-responsive roofing material according to claim 14
wherein the latent-heat storage material constitutes at least ten
percent by weight of the roofing material.
18. A solar heat-responsive roofing material according to claim 14
wherein the thermoplastic polymer is selected from the group
consisting of poly(vinyl ethyl ether), poly(vinyl n-butyl ether)
and polychloroprene.
19. A solar heat-responsive roofing material according to claim 14
wherein the at least one solar heat reflective roofing material has
greater than 40% total reflectance between 700 nm to 2500 nm of
solar radiation.
20. A solar heat-responsive roofing material according to claim 14
further including a reflective coating, with solar-heat reflective
material being dispersed in the reflective coating.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of pending U.S.
application Ser. No. 11/769,530, filed Jun. 27, 2007, which claimed
the priority of provisional application Ser. No. 60/806,777 filed
Jul. 8, 2006.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to roofing products, and
processes for making such products.
[0004] 2. Brief Description of the Prior Art
[0005] Roofing products include sheet or roll roofing employed in
constructing built-up roofs and mineral-surfaced asphalt shingles.
Depending on the specifics of their installation, roofing products
can experience significant thermal shocks on a repeated basis,
reducing the service life of the roof in which they are installed.
For example, a dark colored, south-facing shingled roof installed
at a location at a high elevation can experience a significant rise
in temperature shortly after sunrise on a cloudless day.
[0006] Sheet roofing products are typically employed for flat or
gently sloping roofs. Built-up roofing typically includes one or
more sheets of polymer-modified bitumen, strengthened with a
nonwoven fibrous mat bonded with hot asphalt or a cold adhesive.
Roofing sheets formed from elastomeric materials such as EDPM
rubber and thermoplastic materials such as thermoplastic polyolefin
are also employed to cover flat roofs.
[0007] Mineral surfaced asphalt shingles, such as those described
in ASTM D225 ("Standard Specification for Asphalt Shingles (Organic
Felt) Surfaced with Mineral Granules") or D3462 ("Standard
Specification for Asphalt Shingles Made From Glass Felt and
Surfaced with Mineral Granules"), are generally used on
steep-sloped roofs to provide water-shedding function while adding
an aesthetically pleasing appearance to the roofs. The asphalt
shingles are generally constructed from asphalt-saturated roofing
felts and surfaced with pigmented color granules, such as those
described in U.S. Pat. No. 4,717,614. Pigment-coated mineral rocks
are commonly used as color granules in roofing applications to
provide aesthetic as well as protective functions to the asphalt
shingles. Roofing granules are generally used in asphalt shingle or
in roofing membranes to protect asphalt from harmful ultraviolet
radiation.
[0008] Roofing granules typically comprise crushed and screened
mineral materials, which are subsequently coated with a binder
containing one or more coloring pigments, such as suitable metal
oxides. The granules are employed to provide a protective layer on
asphaltic roofing materials such as shingles, and to add aesthetic
values to a roof.
[0009] In the past, pigments for roofing granules have usually been
selected to provide shingles having an attractive appearance with
little thought to the thermal stresses encountered on shingled
roofs. However, depending on location and climate, roofs, including
shingled roofs, can experience very challenging environmental
conditions, which tend to reduce the effective service life of such
roofs. One significant environmental stress is the elevated
temperature experienced by roofing shingles under sunny, summer
conditions, especially roofing shingles coated with dark colored
roofing granules.
[0010] Conventional built-up roofs and conventional asphalt
shingles are known to have low solar heat reflectance, and hence
will absorb solar heat especially through the near infrared range
(700 nm-2500 nm) of the solar spectrum. In the case of
granule-covered roofing, this phenomenon is increased as the
granules covering the surface become dark in color. For example,
while white-colored asphalt shingles can have solar reflectance in
the range of 25-35%, dark-colored asphalt shingles can have solar
reflectance of only 5-15%. Furthermore, except in the white or very
light colors, there is typically only a very small amount of
pigment in the conventional granule's color coating that reflects
solar radiation well. As a result, it is common to measure
temperatures as high as 77.degree. C. on the surface of black
roofing shingles on a sunny day with 21.degree. C. ambient
temperature. Absorption of solar heat may result in elevated
temperatures at the shingle's surroundings, which can contribute to
the so-called heat-island effects and increase the cooling load to
its surroundings or energy consumption needs for air
conditioning.
[0011] This heat absorption problem has been addressed by applying
white pigment-containing latex coatings directly onto the surface
on the roof. Although such roofs can be coated with solar
reflective paint or coating material, such as a composition
containing a significant amount of titanium dioxide pigment, in
order to reduce such thermal stresses, this utilitarian approach
will often prove to be aesthetically undesirable, especially for
residential roofs. This approach has primarily been employed for
commercial and industrial building roofs. Depending on the
environment, such roofs can become soiled rapidly, substantially
reducing the reflectivity of the roof. Periodic renewal of the
coating may be required. White reflective pigments have also been
incorporated in roofing sheets, such as roofing membranes formed
from thermoplastic polyolefin.
[0012] Another approach is provided by U.S. Pat. No. 2,732,311,
which discloses a method for preparing roofing granules having
metal flakes, such as aluminum flakes, adhered to their surfaces,
to provide a radiation-reflective surface. Additionally, the use of
exterior-grade coatings colored by infrared-reflective pigments for
deep-tone colors, and sprayed onto the roof in the field, has been
proposed. Employing another approach, U.S. Patent Publication
2003/0068469 A1 discloses an asphalt-based roofing material
comprising a mat saturated with asphalt coating and a top coating
having a top surface layer that has a solar reflectance of at least
70%. The high reflectance of the top surface layer is achieved by
embedding metal flakes or a reflective pigment such as titanium
dioxide or zinc sulfide in surface layer (paragraph 48).
Alternatively, minerals with high solar reflectance can be selected
and employed as roofing granules. For example, U.S. Patent
Publication 2003/0152747 A1 discloses the use of granules with
solar reflectance greater than 55% to enhance the solar
reflectivity of asphalt based roofing products. U.S. Patent
Publication 2005/0072114 A1 discloses solar-reflective roofing
granules having deep-tone colors that are formed by coating base
mineral particles with a coating composition including an
infrared-reflective pigment. Color is provided by a colored
infrared pigment, light-interference platelet pigment, or metal
oxide. U.S. Patent Publication 2005/0072110 A1 discloses an
infrared-reflective material applied directly to the bituminous
surface of a roofing product to increase the solar heat reflectance
of the product, even when deep-tone roofing granules are used to
color the product. The infrared-reflective material can be applied
as a powder or in a carrier fluid or film, and can be applied along
with infrared-reflective roofing granules.
[0013] Phase change materials ("PCM") are materials intended to
store heat energy for later release. Uses include modification of
textiles used in extreme or hazardous environments, and modified
wallboard for energy conservation and reducing peak power demand.
Heat is either absorbed or released to effect a phase change, such
as when a material melts or solidifies.
[0014] U.S. Pat. No. 5,770,295 discloses a phase change thermal
insulation system, which includes an inner layer of insulating
material and an outer layer of insulating material with an
intermediate layer of phase change material in between the
insulating layers.
[0015] U.S. Patent Application Publication No. 2004/0170806
discloses tile structures having a PCM component for use in
flooring and ceilings. The PCM component can be an encapsulated
paraffin wax. The tiles preferably include a binder material such
as a polyester resin or styrene monomer, a PCM component, and a
granular base medium such as a granular-sized stone.
[0016] There is a continuing need for roofing materials, and
especially asphalt shingles, that have improved resistance to
thermal stresses while providing an attractive appearance.
SUMMARY OF THE INVENTION
[0017] The present invention provides roofing materials and roofs
formed therefrom that have improved resistance to thermal stresses
and which simultaneously provide an attractive appearance.
[0018] In one embodiment, the present invention provides a solar
heat responsive roofing material comprising a continuous phase, and
a discontinuous phase dispersed in the continuous phase, where the
discontinuous phase has a phase transition at a temperature between
about 50 degrees Celsius and about 95 degrees Celsius, and
preferably between about 60 degrees Celsius and about 85 degrees
Celsius. Preferably, the discontinuous phase has a phase transition
enthalpy of at least about 100 kilojoules per kg, and preferably
constitutes at least ten percent by weight of the roofing material,
and more preferably at least about twenty-five percent by weight of
the roofing material. Preferably, the wherein the discontinuous
phase comprises a lipophilic substance. Preferably, the
discontinuous phase of the roof comprises at least one
heat-responsive substance selected from the group comprising high
temperature waxes and thermoplastic polymers, and the thermoplastic
polymer is preferably selected from the group consisting of
poly(vinyl ethyl ether), poly(vinyl n-butyl ether) and
polychloroprene. In one aspect of the present embodiment of the
invention, the roofing material includes a base sheet having a
bituminous coating comprising the continuous phase. In another
aspect, the roof includes a plurality of coated roofing granules,
and the continuous phase comprises the roofing granule coating. In
one presently preferred aspect of the present invention, the
discontinuous phase is encapsulated in a plurality of capsules. In
this case, the capsules preferably include a capsule wall, and the
capsule wall is preferably formed from a material selected from the
group consisting of poly(meth)acrylates and polyurethanes. In this
case, the capsules preferably have a size ranging from about 1
micrometers to 100 micrometers, and more preferably a size ranging
from about 2 micrometers to 50 micrometers. In another aspect of
the present invention, the discontinuous phase comprises a
plurality of fibers comprising phase change material.
[0019] In another embodiment, the present invention provides a
solar heat-responsive roofing material comprising a bituminous base
sheet; and a plurality of roofing granules, the roofing granules
including a latent heat storage material having a phase transition
at a temperature between about 50 degrees Celsius and about 95
degrees Celsius, and preferably between about 60 degrees Celsius
and about 85 degrees Celsius. Preferably, the heat storage material
has a phase transition enthalpy of at least 100 kilojoules per kg,
and preferably the heat storage material constitutes at least ten
percent by weight of the roofing material, and more preferably at
least thirty percent by weight of the roofing material. Preferably,
the heat storage material is a lipophilic substance. Preferably,
the heat storage material is selected from the group comprising
high temperature waxes and thermoplastic polymers, wherein the
thermoplastic polymer is preferably selected from the group
consisting of poly(vinyl ethyl ether), poly(vinyl n-butyl ether)
and polychloroprene. In one aspect of this embodiment, the heat
storage material is encapsulated in a plurality of capsules.
Preferably, the capsules each include a capsule wall, and the
capsule wall is formed from a material selected from the group
consisting of poly(meth)acrylates and polyurethanes. In this case,
the capsules preferably have a size ranging from about 0.1
millimeters to 10 millimeters, and more preferably ranging from
about 0.5 millimeters to 2 millimeters. In another aspect of this
embodiment, the bituminous base sheet preferably includes a
plurality of fibers comprising phase change material.
[0020] In yet another embodiment, the present invention provides a
solar heat-responsive roofing material comprising at least one
solar-heat reflective material; and at least one latent-heat
storage material, the at least one latent-heat storage material
having a phase transition at a temperature between about 50 degrees
Celsius and about 95 degrees Celsius, and preferably between about
60 degrees Celsius and about 85 degrees Celsius. Preferably, the
latent-heat storage material has a phase transition enthalpy of at
least about 100 kilojoules per kg. Preferably, the heat storage
material constitutes at least ten percent by weight of the roofing
material, and more preferably at least about thirty percent by
weight of the roofing material. Preferably, the heat storage
material is a lipophilic substance. Preferably, the heat storage
material comprises at least one heat-responsive substance selected
from the group comprising high temperature waxes and thermoplastic
polymers, and the thermoplastic polymer is preferably selected from
the group consisting of poly(vinyl ethyl ether), poly(vinyl n-butyl
ether) and polychloroprene. In this embodiment of the present
invention, the at least one solar heat reflective roofing material
preferably has greater than 40% total reflectance between 700 nm to
2500 nm of solar radiation. In this embodiment, the solar
heat-responsive roofing material preferably includes a continuous
phase, and a discontinuous phase dispersed in the continuous phase,
wherein the discontinuous phase includes the latent-heat storage
material. In one aspect of this embodiment, the roofing material
preferably includes a base sheet having a bituminous coating
comprising the continuous phase. In this aspect of this embodiment,
the roofing material preferably includes a plurality of coated
roofing granules, and the continuous phase comprises the roofing
granule coating. In one variation of this embodiment, the
discontinuous phase is preferably encapsulated in a plurality of
capsules. In this variation, the capsules each include a capsule
wall, and the capsule wall is preferably formed from a material
selected from the group consisting of poly(meth)acrylates and
polyurethanes. Preferably, the capsules have a size ranging from
about 1 micrometer to 100 micrometers, and more preferably from
about 2 micrometers to 50 micrometers.
[0021] In one aspect of this embodiment of the present invention,
the solar-reflective roofing preferably includes a bituminous base
sheet; and a plurality of roofing granules, and the roofing
granules include the latent-heat storage material. In this case,
the storage material is preferably encapsulated in a plurality of
capsules. Here, the capsules preferably include a capsule wall,
with the capsule wall being formed from a material selected from
the group consisting of poly(meth)acrylates and polyurethanes. In
this case, the capsules preferably have a size ranging from about
0.1 millimeters to 10 millimeters, more preferably from about 0.5
millimeters to 2 millimeters.
[0022] In another aspect of this embodiment of the present
invention, the solar heat-responsive roofing material preferably
includes a reflective coating, and the solar-heat responsive
material is dispersed in the reflective coating. In this aspect,
the solar heat-responsive roofing material preferably comprises a
bituminous base sheet; and a plurality of roofing granules, with
the roofing granules including the latent-heat storage material. In
one variation of this aspect of the present invention, the
reflective coating is preferably applied to the bituminous base
sheet. In another variation of this aspect of the present
embodiment, the reflective coating is preferably applied to the
roofing granules.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a schematic illustration of a solar heat
responsive roofing material according to a first embodiment of the
present invention.
[0024] FIG. 2 is a schematic illustration of a solar heat
responsive roofing material according to a second embodiment of the
present invention.
[0025] FIG. 3 is a schematic illustration of a solar heat
responsive roofing material according to a third embodiment of the
present invention.
[0026] FIG. 4 is a schematic illustration of a solar heat
responsive roofing material according to a fourth embodiment of the
present invention.
[0027] FIG. 5 is a schematic illustration of a solar heat
responsive roofing material according to a fifth embodiment of the
present invention.
[0028] FIG. 6 is a schematic illustration of a solar heat
responsive roofing material according to a sixth embodiment of the
present invention.
[0029] FIG. 7 is a schematic illustration of a solar heat
responsive roofing material according to a seventh embodiment of
the present invention.
[0030] FIG. 8 is a schematic illustration of a solar heat
responsive roofing material according to a eighth embodiment of the
present invention.
[0031] FIG. 9 is a schematic illustration of a solar heat
responsive roofing material according to a ninth embodiment of the
present invention.
DETAILED DESCRIPTION
[0032] The present invention provides roofing materials and roofs
formed therefrom that have improved resistance to thermal stresses
by the inclusion of suitable phase change material in the roofing
materials.
[0033] Phase change materials for use in the roofing materials of
the present invention preferably have a phase transition at a
temperature between about 50 degrees Celsius and about 95 degrees
Celsius, and more preferably between about 60 degrees Celsius and
about 85 degrees Celsius. Preferably, the latent heat accompanying
the phase change is at least about 100 kilojoules per kilogram. The
phase change experienced by the phase change material depends upon
the specific phase change material employed, but can be fusion or
crystallization, or another type of phase change, such as eutectic
melting or transitions between solid phases. Preferably, the phase
change does not result in a substantial volume change, as in the
case of vaporization. Preferably, the phase change material is a
chemically inert material, or a material with limited chemical
reactivity.
[0034] Preferably, the phase change material is selected from the
higher paraffins, and in particular, from the paraffins having a
melting point within the preferred phase transition temperature
range, including, for example, n-tetracosane (melting point 50.9
degrees C., latent heat of fusion 255 kJ/kg), n-pentacosane
(melting point 53.7 degrees C., latent heat of fusion 238 kJ/kg),
n-hexacosane (melting point 56.4 degrees C., latent heat of fusion
257 kJ/kg), n-heptacosane (melting point 59.0 degrees C., latent
heat of fusion 236 kJ/kg), n-octacosane (61.4 degrees C., latent
heat of fusion 255 kJ/kg), n-nonacosane (melting temperature 64
degrees C., latent heat of fusion 240 kJ/kg), n-triacontane
(melting temperature 65 degrees C., latent heat of fusion, 252
kJ/kg), n-hentriacontane, n-dotriacontane (melting point 70 degrees
C.) n-tritriacontane (melting point 71 degrees C., latent heat of
fusion 189 kJ/kg), and mixtures thereof. Suitable mixtures may
include lower paraffins, such as, for example, n-dodecane,
n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane,
n-heptadecane, n-octadecane, n-nonadecane, n-eiscosane,
n-heneicosane, n-docosane, and n-tricosane. However, the average
melting point of such mixtures is preferably between about 50
degrees Celsius and about 93.3 degrees Celsius, and more preferably
between about 60 degrees Celsius and about 82.2 degrees
Celsius.
[0035] Preferably, the phase change composition is selected so that
subcooling is avoided. For example, when a paraffinic phase change
material is employed, it is preferred that a nucleating agent be
included in the composition when phase change material is provided
in a finely distributed phase, such as disclosed for example, in
U.S. Patent Publication 2004/0076826. Suitable nucleating agents
include paraffinic alcohols and amines, such as, for example,
1-hexacosanol, 1-pentacosanol, 1-tridecanol, pentadecylamine,
eicosylamine, and docosylamine.
[0036] Other phase change materials that can be employed in the
present invention include fatty acids, salt hydrates and other
inorganic materials, eutectic mixtures, esters, alcohols and
glycols. Suitable inorganic materials include antimony trichloride
(melting point 73.4 degrees C., latent heat of fusion 25 kJ/kg).
Suitable organic materials include camphene (melting point 50
degrees C., latent heat of fusion 238 kJ/kg), 9-heptadecanone
(melting point 51 degrees C., latent heat of fusion 213 kJ/kg),
methyl behenate (melting point 52 degrees C., latent heat of fusion
234 kJ/kg), pentadeconoic acid (melting point 52.5 degrees C.,
latent heat of fusion 178 kJ/kg), hypophosphoric acid (H4P2O6,
melting point 55.0 degrees C., latent heat of fusion 213 kJ/kg),
choroacetic acid (melting point 56 degrees C., latent heat of
fusion 130 kJ/kg), potassium octanoate (melting point 57 degrees
C.), heptadecanoic acid (melting point 60.6 degrees C., latent heat
of fusion 189 kJ/kg), potassium heptanoate (melting point 61
degrees C.), bees wax (melting point 61.8 degrees C., latent heat
of fusion 177 kJ/kg), glycolic acid (melting point 63 degrees C.,
latent heat of fusion 109 kJ/kg), ammonium biacetate (melting point
65-66 degrees C., latent heat of fusion 146-159 kJ/kg),
n-eicosanoic acid (melting point 76.5 degrees C., latent heat of
fusion 227 kJ/kg), (+)-3-bromocamphor (melting point 77 degree C.,
latent heat of fusion 174 kJ/kg), potassium propionate (melting
point 79 degrees C.), durene (melting point 79.3 degrees C., latent
heat of fusion 156 kJ/kg), acetamide (meting point 81 degrees C.,
latent heat of fusion 241 kJ/kg), and methyl 4-bromobenzoate
(melting point 81 degrees C., latent heat of fusion 126 kJ/kg).
Suitable fatty acids for use as PCM in the present invention
include myristic acid (melting point 49-51 degrees C., latent heat
of fusion 205 kJ/kg), palmitic acid (melting point 64 degrees C.,
latent heat of fusion 185.4 kJ/kg) and stearic acid (melting point
69 degrees C., latent heat of fusion 202.5 kJ/kg). Suitable salt
hydrates include Ca(NO.sub.3).sub.2.3H2O (melting point 51 degrees
C., latent heat of fusion 104 kJ/kg), Na(NO.sub.3).sub.2.6H2O
(melting point 53 degrees C., latent heat of fusion 158 kJ/kg),
Zn(NO.sub.3).sub.2.2H2O (melting point 55 degrees C., latent heat
of fusion 68 kJ/kg), FeCl.sub.3.2H.sub.2O (melting point 56 degrees
C., latent heat of fusion 90 kJ/kg), Co(NO.sub.3).sub.2.6H.sub.2O
(melting point 57 degrees C., latent heat of fusion 115 kJ/kg),
Ni(NO.sub.3).sub.2.6H.sub.2O (melting point 57 degrees C., latent
heat of fusion 168 kJ/kg), MnCl.sub.2.4H.sub.2O (melting point 58
degrees C., latent heat of fusion 151 kJ/kg),
CH.sub.3COONa.3H.sub.2O (melting point 58 degrees C., latent heat
of fusion 270-290 kJ/kg), LiC.sub.2H.sub.3O.sub.2.2H.sub.2O
(melting point 58 degrees C., latent heat of fusion 251-377 kJ/kg),
MgCl.sub.2.4H.sub.2O (melting point 58.0 degrees C., latent heat of
fusion 178 kJ/kg), NaOH.H2O (melting point 58 degrees C., latent
heat of fusion 272 kJ/kg), Cd(NO.sub.3).sub.2.4H.sub.2O (melting
point 59 degrees C., latent heat of fusion 98 kJ/kg),
Cd(NO.sub.3).sub.2.1H.sub.2O (melting point 59.5 degrees C., latent
of fusion 107 kJ/kg), Fe(NO.sub.3).sub.2.6H.sub.2O (melting point
60 degrees C., latent of fusion 125 kJ/kg),
NaAl(SO.sub.4).sub.2.12H.sub.2O (melting point 61 degrees C.,
latent of fusion 181 kJ/kg), FeSO.sub.4.7H.sub.2O (melting point 64
degrees C., latent of fusion 200 kJ/kg),
Na.sub.3PO.sub.4.12H.sub.2O (melting point 65 degrees C., latent of
fusion 168 kJ/kg), Na.sub.2B.sub.4O.sub.7.10H.sub.2O (melting point
68 degrees C.), Na.sub.3PO.sub.4.12H.sub.2O (melting point 69
degrees C.), LiCH.sub.3COO.2H.sub.2O (melting point 70 degrees C.,
latent of fusion 150-251 kJ/kg), Na.sub.2P.sub.2O.sub.7.10H.sub.2O
(melting point 70 degrees C., latent of fusion 186-230 kJ/kg),
Al(NO.sub.3).sub.2.9H.sub.2O (melting point 72 degrees C., latent
of fusion 155-176 kJ/kg), Ba(OH).sub.2.8H.sub.2O (melting point 78
degrees C., latent of fusion 265-280 kJ/kg),
A12(SO.sub.4).sub.3.18H.sub.2O (melting point 88 degrees C., latent
of fusion 218 kJ/kg), Sr(OH).sub.2.8H.sub.2O (melting point 89
degrees C., latent of fusion 370 kJ/kg),
Mg(NO.sub.3).sub.2.6H.sub.2O (melting point 89-90 degrees C.,
latent of fusion 162-167 kJ/kg), KAI(SO.sub.4).sub.2.12H.sub.2O
(melting point 91 degrees C., latent of fusion 184 kJ/kg), and
(NNAI(SO.sub.4).6H.sub.2O (melting point 95 degrees C., latent of
fusion 269 kJ/kg). Suitable eutectic mixtures include mixtures of
13-16 weight percent LiNO.sub.3, 19-21 weight percent KNO.sub.3,
and 63-68 weight percent Mg(NO.sub.3)2.6H.sub.2O (melting point 52
degrees C.), mixtures of 61.5 weight percent Mg(NO.sub.3).6H.sub.2O
and 38.4 weight percent NH.sub.4NO.sub.3 (melting point 52 degrees
C., latent heat of fusion 125.5 kJ/kg), mixtures of 58.7 weight
percent Mg(NO.sub.3).6H.sub.2O and 41.3 weight percent
MgCl.sub.2.6H.sub.2O (melting point 59 degrees C., latent heat of
fusion 132.2 kJ/kg), mixtures of 53 weight percent
Mg(NO.sub.3).6H.sub.2O and 47 weight percent
Al(NO.sub.3).sub.2.9H.sub.2O (melting point 61 degrees C., latent
heat of fusion 148 kJ/kg), mixtures of 59 weight percent
Mg(NO.sub.3).6H.sub.2O and 41 weight percent MgBr.sub.2.6H.sub.2O
(melting point 66 degrees C., latent heat of fusion 168 kJ/kg),
mixtures of 67.1 weight percent naphthalene and 32.9 weight percent
benzoic acid (melting point 67 degrees C., latent heat of fusion
123.4 kJ/kg), mixtures of 10-12 weight percent LiNO.sub.3, 6-8
percent by weight NaNO.sub.3, and 80-84 percent by weight
Mg(NO.sub.3)2.6H.sub.2O (melting point 67 degrees C.), mixtures of
79 weight percent AlCl.sub.3, 17 weight percent NaCl, and 4 weight
percent ZrCl2 (melting point 68 degrees C., latent heat of fusion
234 kJ/kg), mixtures of 66 weight percent AlCl.sub.3, 20 weight
percent NaCl, and 14 weight percent KCl (melting point 70 degrees
C., latent heat of fusion 209 kJ/kg), mixtures of 66.6 weight
percent NH.sub.2CONH.sub.2 and 34.4 weight percent NH4Br (melting
point 76 degrees C., latent heat of fusion 151 kJ/kg), mixtures of
25 weight percent LiNO.sub.3, 65 weight percent NH.sub.4NO.sub.3,
and 10 weight percent NaNO.sub.3 (melting point 80.5 degrees C.,
latent heat of fusion 113 kJ/kg), mixtures of 60 weight percent
AlCl.sub.3, 26 weight percent NaCl, and 14 weight percent KCl
(melting point 93 degrees C., latent heat of fusion 213 kJ/kg), and
mixtures of 66 weight percent AlCl.sub.3 and 34 weight percent NaCl
(melting point 93 degrees C., latent heat of fusion 201 kJ/kg).
Examples of phase change materials having solid-solid phase
transitions that can be employed in the present invention include
diamino-pentaerythritol (solid-solid transition temperature 68
degrees C., enthalpy of phase transition 184 kJ/kg),
2-amino-2-methyl-1,3-propanediol (solid-solid transition
temperature 78 degrees C., enthalpy of phase transition 264 kJ/kg),
2-methyl-2-nitro-1,3-propanediol (solid-solid transition
temperature 79 degrees C., enthalpy of phase transition 201 kJ/kg),
trimethylolethane (solid-solid transition temperature 81 degrees
C., enthalpy of phase transition 192 kJ/kg), and
monoamino-pentaerythritol (solid-solid transition temperature 86
degrees C., enthalpy of phase transition 192 kJ/kg). Examples of
polymeric materials that can be employed as phase change material
in the present invention include thermoplastic polymers such as
poly(vinyl ethyl ether), poly(vinyl n-butyl ether) and
polychloroprene, polyethylene glycols such as Carbowax.TM.
polyethylene glycol 4600 (melting temperature 57-61 degrees C.),
Carbowax polyethylene glycol 8000 (melting point temperature 60-63
degrees C., heat of fusion 167.5 kJ/kg), and Carbowax polyethylene
glycol 14,000 (melting point temperature 61-67 degrees C.), and
polyolefins such as lightly crosslinked polyethylene (solid-solid
transition temperature 81 degrees C., enthalpy of phase transition
192 kJ/kg), and high density polyethylene (solid-solid transition
temperature 125-146 degrees C., enthalpy of phase transition
167-201 kJ/kg).
[0037] The phase change materials employed in the present invention
are preferably dispersed as a discontinuous phase in a continuous
phase of another, non-PCM material.
[0038] Preferably, in order to facilitate preparation of the
roofing materials of the present invention, the phase change
materials are provided in the form of microcapsules.
[0039] The phase change material can be encapsulated in
microcapsules using conventional techniques for forming
microcapsules, including such techniques as interfacial
polymerization, phase separation/coacervation, spray drying, spray
coating, fluid bed coating, supercritical anti-solvent
precipitation, and the like. Techniques for microencapsulating
solid particles are disclosed, for example, in G. Beestman,
"Microencapsulation of Solid Particles" (H. B. Scher, Ed., Marcel
Dekker, Inc. New York 1999) pp. 31-54, Kirk-Othmer Encyclopedia of
Chemical Technology, 4th Edition; as well in U.S. Pat. Nos.
6,156,245, 6,797,277, and 6,861,145.
[0040] The microencapsulation of phase change material is
well-known in the art, and is disclosed for example, in U.S. Pat.
No. 4,708,812 (encapsulation of solid phase change material for
thermal energy storage with a shell of an elastomeric condensation
polymer, such as polyurethane-urea, to permit for the change in
volume accompanying phase transitions), incorporated hereby by
reference.
[0041] The preferred size of the microcapsules employed depends
upon their location in the roofing material. When microcapsules
containing phase change materials are distributed in roofing
granule coatings, the PCM microcapsules preferably have an average
size that is less than the thickness of the coating layer. Thus,
when the PCM microcapsules are distributed in a roofing granule
coating, the PCM microcapsules preferably have an average size of
from about 1 micrometer to 100 micrometers, and more preferably
from about 2 micrometers to 50 micrometers. When PCM microcapsules
are distributed in the core of a PCM roofing granule, the PCM
microcapsules preferably have an average size that is less than
about one-half the average size of the cores. Thus, when the PCM
microcapsules are distributed in the roofing granule cores, the PCM
microcapsules preferably have an average size of from about 0.1
millimeters to 10 millimeters, more preferably from about 0.5
millimeters to 2 millimeters. When the PCM microcapsules are
distributed in a roofing material membrane, the PCM microcapsules
preferably have an average size that is less than the membrane
thickness. Thus, when PCM microcapsules are distributed in a
roofing material membrane, the PCM microcapsules preferably have an
average size of from about 1 micrometer to 100 micrometers, and
more preferably from about 2 micrometers to 50 micrometers.
[0042] Preferably, the microcapsules formed have an average size of
from about 200 micrometers to about 5 millimeters, and more
preferably of from about 400 micrometers to about 2 mm.
[0043] In some cases, for example, when phase change material is to
be incorporated in roofing granules, microcapsules containing phase
change material can be themselves encapsulated in macrocapsules
(having an average particle size of, for example, from about 0.1 to
10 mm), such as disclosed in U.S. Pat. No. 6,703,127. The
macrocapsules can then in turn be agglomerated with inert material
to form roofing granules, which can be subsequently coated with
reflective material, etc. Alternatively, the phase change material
can be adsorbed on a finely divided solid microporous material such
as amorphous silica or a zeolite, such as disclosed in U.S. Pat.
No. 6,063,312.
[0044] Phase changes are typically accompanied by volume changes.
Although the extent of the volume change accompanying a solid to
liquid phase transition or a solid-solid phase transition is
typically much smaller than the volume change accompanying a liquid
to gas phase transition, the contemplated volume change should be
accommodated in preparing the roofing materials of the present
invention. Thus, when the dispersed phase change material is
packaged in microcapsules, it is preferred that the microcapsule
wall be formed from an elastomeric polymer to permit the expansion
and contraction of the phase change material undergoing the phase
transition. In the alternative, the phase change material can be
packaged within the microcapsules with sufficient void volume to
accommodate the contemplated phase change without rupture of the
microcapsule walls. This can be accomplished, for example, by
employing a volatile diluent for the phase change material. A
solution of the phase change material and the diluent is
encapsulated. The diluent can be selected so that it can escape
through the microcapsule walls after formation of the
microcapsules.
[0045] The roofing materials of the present invention can include
phase change materials in any one or more of several different
locations, depending on the specific structure of the roofing
material. For example, when the roofing material is a membrane
formed from a thermoplastic polymeric material such as
thermoplastic polyolefin (TPE), the phase change material can be
distributed as a discontinuous phase within a continuous phase
formed by the thermoplastic polymeric material. As another example,
when the roofing material is an asphalt roofing shingle including
both a bituminous membrane and a surface coating of protective
roofing granules, the phase change material can be included in the
roofing granules, in the bituminous membrane, or both. Roofing
granules typically include a core material, which can be covered
with a layer including colorants to provide an attractive
appearance. In the present invention, the phase change material can
be included in the roofing granule core, in one or more coating(s)
for the core, or in both the core and the coating(s), to form "PCM"
roofing granules.
[0046] When phase change material is located in the core of the
roofing granule, the core can be composed of a single type phase
change material, a mixture of two or more types of phase change
materials, or a mixture of one or more types of phase change
materials with one or more types of non-phase change materials.
Such roofing granule cores can be prepared by initially preparing a
porous core of non-phase change material, such as disclosed for
example in U.S. Patent Publication No. 2004-0258835, and
subsequently immersing the porous cores in the liquid phase of a
suitable phase change material to permit the phase change material
to be drawn into the cores by osmotic forces.
[0047] Alternatively, the cores of PCM roofing granules can be
composed of an agglomeration of microcapsules containing phase
change materials and other material, such as inert mineral
materials. In the alternative, the cores of PCM roofing granules
can be formed from microcapsules containing phase change materials,
and dispersed in a continuous core binder material, such as a
siliceous binder material.
[0048] When phase change material is located in the outside the
core of the roofing granule, the core can be coated with one or
more layers. For example, the core can be formed from an inert
mineral material, and coated with a layer of microcapsules
including phase change material dispersed in a continuous binder.
The layer including the microcapsules can in turn be covered with
an outer layer that does not contain phase change materials, but
instead may contain colorants, pigments, solar heat reflection
pigments, algae-resistance materials such as copper oxide and zinc
oxide, and the like.
[0049] The PCM roofing granules of the present invention can
include solar heat reflection pigments, examples of which include
white titanium dioxide pigments provided by Du Pont de Nemours,
P.O. Box 8070, Wilmington, Del. 19880.
[0050] The PCM roofing granules of the present invention can
include algae-resistance materials, examples of which include
copper materials, zinc materials, and mixtures thereof. For
example, cuprous oxide and/or zinc oxide, or a mixture thereof, can
be used. The copper materials that can be used in the present
invention include cuprous oxide, cupric acetate, cupric chloride,
cupric nitrate, cupric oxide, cupric sulfate, cupric sulfide,
cupric stearate, cupric cyanide, cuprous cyanide, cuprous stannate,
cuprous thiocyanate, cupric silicate, cuprous chloride, cupric
iodide, cupric bromide, cupric carbonate, cupric fluoroborate, and
mixtures thereof. The zinc materials can include zinc oxide, such
as French process zinc oxide, zinc sulfide, zinc borate, zinc
sulfate, zinc pyrithione, zinc ricinoleate, zinc stearate, zinc
chromate, and mixtures thereof. In one embodiment, it is preferred
that the phase change roofing materials of the present invention
include at least one algaecide, the at least one algaecide
preferably comprising cuprous oxide. In this case, it is preferred
that the cuprous oxide comprises at least 2 percent of the roofing
granule. In another embodiment, the at least one algaecide
preferably comprises zinc oxide, and it is preferred that the zinc
oxide comprises at least 0.1 percent by weight of the roofing
granule.
[0051] When a mixed algaecide is employed, the algae-resistant
material preferably comprises a mixture of cuprous oxide and zinc
oxide.
[0052] The PCM roofing granules of the present invention can be
colored using conventional coatings pigments. Examples of coatings
pigments that can be used include those provided by the Color
Division of Ferro Corporation, 4150 East 56th St., Cleveland, Ohio
44101, and produced using high temperature calcination, including
PC-9415 Yellow, PC-9416 Yellow, PC-9158 Autumn Gold, PC-9189 Bright
Golden Yellow, v-9186 Iron-Free Chestnut Brown, V-780 Black, V0797
IR Black, V-9248 Blue, PC-9250 Bright Blue, PC-5686 Turquoise,
V-13810 Red, V-12600 Camouflage Green, V12560 IR Green, V-778 IR
Black, and V-799 Black.
[0053] Roofing granules typically comprise crushed and screened
mineral materials, which are subsequently coated with a binder
containing one or more coloring pigments, such as suitable metal
oxides. The granules are employed to provide a protective layer on
asphaltic roofing materials such as shingles, and to add aesthetic
values to a roof.
[0054] In preparing PCM roofing granules according to the present
invention, one or more exterior coating layers can be applied to
the base particles. The exterior coating layers can include phase
change material, and preferably includes a suitable coating binder.
The coating binder can be an inorganic or organic material, and is
preferably formed from a polymeric organic material or a
silicaceous material, such as a metal-silicate binder, for example
an alkali metal silicate, such as sodium silicate. The choice of
binder preferably reflects the choice of the phase change material,
and whether the phase change material is contained in microcapsules
and if so, the nature of the material from which the microcapsule
is formed. Preferably, the binder is selected to avoid loss or
degradation of the phase change material or the microcapsule wall
during cure of the binder. Similarly, when the phase change
material is incorporated in the roofing granule core and a binder
material for the core is employed, the core binder material is also
preferably selected so that loss or degradation of the phase change
material or the microcapsule wall material (if present) is avoided
during cure of the core binder material.
[0055] When a metal-silicate binder is employed in the preparation
of PCM granules of the present invention, the binder preferably
includes a heat-reactive aluminosilicate material, such as clay,
preferably, kaolin. Alternatively, the metal silicate binder can be
insolubilized chemically by reaction with an acidic material, for
example, ammonium chloride, aluminum chloride, hydrochloric acid,
calcium chloride, aluminum sulfate, or magnesium chloride, such as
disclosed in U.S. Pat. Nos. 2,591,149, 2,614,051, 2,898,232 and
2,981,636, each incorporated herein by reference, or other acidic
material such as aluminum fluoride. In another alternative, the
binder can be a controlled release sparingly water soluble glass
such as a phosphorous pentoxide glass modified with calcium
fluoride, such as disclosed in U.S. Pat. No. 6,143,318,
incorporated herein by reference.
[0056] If the phase change material is to be incorporated only in
one or more exterior coatings for the roofing granules, inert base
particles can be employed. Suitable inert base particles, for
example, mineral particles with size passing #8 mesh and retaining
on #70 mesh, can be coated with a combination of a phase change
material, metal-silicate binder, kaolin clay, color pigments such
as metal oxide pigments to reach desirable colors, followed by a
heat treatment to obtain a durable coating.
[0057] When the PCM roofing granules are fired at an elevated
temperature, such as at conditions of at least about 800 degrees
F., and preferably at temperatures from about 1,000 to about 1,200
degrees F., the clay binder densifies to form strong particles.
[0058] Examples of clays that can be employed in preparing PCM
roofing granules fo the present invention include kaolin, other
aluminosilicate clays, Dover clay, bentonite clay, etc.
[0059] In the alternative, a suitable silicaceous binder can be
formed from sodium silicate, modified by the addition of at least
one of sodium fluorosilicate, aluminum fluoride, or Portland
cement.
[0060] In one presently preferred embodiment, the roofing material
of the present invention includes at least one solar heat
reflective material.
[0061] The solar heat-reflective material can be an
infrared-reflective functional pigment selected from the group
consisting of light-interference platelet pigments including mica,
light-interference platelet pigments including titanium dioxide,
mirrorized silica pigments based upon metal-doped silica, and
alumina.
[0062] When alumina is employed as the at least one solar
heat-reflective pigment, the alumina (aluminum oxide) preferably
has a particle size less than #40 mesh (425 microns), preferably
between 0.1 micron and 5 microns, and more preferably between 0.3
micron and 2 microns. It is preferred that the alumina includes
greater than 90 percent by weight Al2O3, and more preferably,
greater than 95% by weight Al2O3.
[0063] The at least one solar heat-reflective pigment can comprise
a solid solution including iron oxide, such as disclosed in U.S.
Pat. No. 6,174,360, incorporated herein by reference. The solar
heat-reflective pigment can also comprise a near
infrared-reflecting composite pigment such as disclosed in U.S.
Pat. No. 6,521,038, incorporated herein by reference. Composite
pigments are composed of a near-infrared non-absorbing colorant of
a chromatic or black color and a white pigment coated with the near
infrared-absorbing colorant. Near-infrared non-absorbing colorants
that can be used in the present invention are organic pigments such
as organic pigments including azo, anthraquinone, phthalocyanine,
perinone/perylene, indigo/thioindigo, dioxazine, quinacridone,
isoindolinone, isoindoline, diketopyrrolopyrrole, azomethine, and
azomethine-azo functional groups. Preferred black organic pigments
include organic pigments having azo, azomethine, and perylene
functional groups.
[0064] Examples of near infrared-reflective pigments available from
the Shepherd Color Company, Cincinnati, Ohio, include Arctic Black
10C909 (chromium green-black), Black 411 (chromium iron oxide),
Brown 12 (zinc iron chromite), Brown 8 (iron titanium brown
spinel), and Yellow 193 (chrome antimony titanium).
[0065] Light-interference platelet pigments are known to give rise
to various optical effects when incorporated in coatings, including
opalescence or pearlescence. Surprisingly, light-interference
platelet pigments have been found to provide or enhance
infrared-reflectance of roofing granules coated with compositions
including such pigments.
[0066] Examples of light-interference platelet pigments that can be
employed in the process of the present invention include pigments
available from Wenzhou Pearlescent Pigments Co., Ltd., No. 9 Small
East District, Wenzhou Economical and Technical Development Zone,
Peoples Republic of China, such as Taizhu TZ5013 (mica, rutile
titanium dioxide and iron oxide, golden color), TZ5012 (mica,
rutile titanium dioxide and iron oxide, golden color), TZ4013 (mica
and iron oxide, wine red color), TZ4012 (mica and iron oxide, red
brown color), TZ4011 (mica and iron oxide, bronze color), TZ2015
(mica and rutile titanium dioxide, interference green color),
TZ2014 (mica and rutile titanium dioxide, interference blue color),
TZ2013 (mica and rutile titanium dioxide, interference violet
color), TZ2012 (mica and rutile titanium dioxide, interference red
color), TZ2011 (mica and rutile titanium dioxide, interference
golden color), TZ1222 (mica and rutile titanium dioxide, silver
white color), TZ1004 (mica and anatase titanium dioxide, silver
white color), TZ4001/600 (mica and iron oxide, bronze appearance),
TZ5003/600 (mica, titanium oxide and iron oxide, gold appearance),
TZ1001/80 (mica and titanium dioxide, off-white appearance),
TZ2001/600 (mica, titanium dioxide, tin oxide, off-white/gold
appearance), TZ2004/600 (mica, titanium dioxide, tin oxide,
off-white/blue appearance), TZ2005/600 (mica, titanium dioxide, tin
oxide, off-white/green appearance), and TZ4002/600 (mica and iron
oxide, bronze appearance).
[0067] Examples of light-interference platelet pigments that can be
employed in the process of the present invention also include
pigments available from Merck KGaA, Darmstadt, Germany, such as
Iriodin.RTM. pearlescent pigment based on mica covered with a thin
layer of titanium dioxide and/or iron oxide; Xirallic.TM. high
chroma crystal effect pigment based upon Al2O3 platelets coated
with metal oxides, including Xirallic T 60-10 WNT crystal silver,
Xirallic T 60-20 WNT sunbeam gold, and Xirallic F 60-50 WNT
fireside copper; ColorStream.TM. multi color effect pigments based
on SiO2 platelets coated with metal oxides, including ColorStream F
20-00 WNT autumn mystery and ColorStream F 20-07 WNT viola fantasy;
and ultra interference pigments based on TiO2 and mica.
[0068] Examples of mirrorized silica pigments that can be employed
in the process of the present invention include pigments such as
Chrom Brite.TM. CB4500, available from Bead Brite, 400 Oser Ave,
Suite 600, Hauppauge, N.Y. 11788.
[0069] The solar heat-reflective material can also be a white
pigment. Examples of white pigments that can be employed in the
present invention include rutile titanium dioxide, anatase titanium
dioxide, lithopone, zinc sulfide, zinc oxide, lead oxide, and void
pigments such as spherical styrene/acrylic beads (Ropaque.RTM.
beads, Rohm and Haas Company), and hollow glass beads having
pigmentary size for increased light scattering. Preferably, the at
least one solar heat-reflective pigment is selected from the group
consisting of titanium dioxide, zinc oxide and zinc sulfide.
[0070] Preferably, the at least one solar heat reflective roofing
material has greater than 40% total reflectance between 700 nm to
2500 nm of solar radiation.
[0071] When the at least one solar heat-reflective material is
incorporated in a coating composition, it is preferred that the at
least one solar heat-reflective pigment comprises from about 10
percent by weight to about 40 percent by weight of the coating
composition. It is more preferred that the at least one solar
heat-reflective pigment comprises from about 20 percent by weight
to about 30 percent by weight of the coating composition.
[0072] Referring now to the figures there is shown in FIG. 1, a
schematic illustration of a solar heat responsive roofing material
10 according to a first embodiment of the present invention. The
solar heat responsive roofing material comprises a flexible
thermoplastic polyolefin membrane 12 having finely divided white
titanium dioxide pigment particles dispersed therein to provide for
solar heat reflectance, reinforced with a polyester scrim 14. The
thermoplastic olefin membrane constitutes a continuous phase, in
which is dispersed as a discontinuous phase a multitude of elements
16 comprising phase change material 18 having a fusion temperature
between 50 degrees C. and 95 degrees C. encapsulated in a flexible
elastomeric wall 20. The thermoplastic polyolefin membrane 12 has a
thickness of about 0.15 cm, and the average size of the PCM
microcapsules 16 is about 0.03 cm.
[0073] FIG. 2 is a schematic illustration of a solar heat
responsive roofing material 30 according to a second embodiment of
the present invention. In this embodiment, a membrane 32 is formed
from a pair of continuous bituminous layers 34 sandwiching a
reinforcing glass fiber scrim 36. The upper bituminous layer 38 and
lower bituminous layer 40 form continuous phase in which is
dispersed a discontinuous phase formed from microcapsules 42
comprising phase change material 44 having a fusion temperature
between 50 degrees C. and 95 degrees C. encapsulated in a flexible
elastomeric wall 46. Partially embedded in the upper surface of the
upper bituminous layer 38 are a plurality of roofing granules 50
comprising an inert mineral core 52 coated with a layer 54 of a
cured coating composition. The coating composition can include
conventional metal oxide pigments, and/or one or more solar
reflective pigments, such as titanium dioxide.
[0074] FIG. 3 is a schematic illustration of solar heat responsive
roofing material 60 according to a third embodiment of the present
invention. In this embodiment, a membrane is formed by a pair of
bituminous layers 62 reinforced by an embedded reinforcing scrim 64
of glass fibers. The top or upper bituminous layer 66 is surfaced
with a plurality of roofing granules 70 formed from an inert
mineral core 72 and covered with a layer 74 of a cured coating
composition. The coating composition layer 74 includes a continuous
coating binder 76 in which are dispersed microcapsules 78 having an
exterior wall 80 encapsulating a core 82 of phase change material.
The coating composition layer 74 can also include conventional
metal oxide colorants as well as, optionally, one or more solar
reflective pigments.
[0075] FIG. 4 is a schematic illustration of a solar heat
responsive roofing material 90 according to a fourth embodiment of
the present invention. In this embodiment, the roofing material 90
includes a bituminous membrane 92 reinforced with a fibrous scrim
94. The scrim 94 includes fibers formed from a phase change
material as well as conventional glass fibers. Fibers 96 formed
from the phase change material are also dispersed above and below
the scrim 94 within the bituminous membrane 92.
[0076] FIG. 5 is a schematic illustration of a solar heat
responsive roofing material 100 according to a fifth embodiment of
the present invention. In this embodiment, the roofing material 100
includes a bituminous membrane 102 reinforced with a scrim 104
formed from glass fibers. Partially embedded in the upper surface
106 of the bituminous membrane 102 are a plurality of composite
roofing granules 110 having nuclei 112 formed from capsules 114
including cores 116 of phase change material covered with an
exterior wall 118 bound together with a siliceous matrix 120, and
covered with a layer 122 of a cured coating composition in which
are dispersed conventional iron oxide pigments.
[0077] FIG. 6 is a schematic illustration of a solar heat
responsive roofing material 130 according to a sixth embodiment of
the present invention. In this embodiment, the roofing material 130
includes a bituminous membrane 132 reinforced with a fibrous scrim
134. The scrim 134 includes fibers formed from a phase change
material as well as conventional glass fibers. Fibers 138 formed
from the phase change material are also dispersed above and below
the scrim 134 within the bituminous membrane 132. Partially
embedded in the upper surface 136 of the bituminous membrane 132
are a plurality of roofing granules 140 comprising an inert mineral
core 142 coated with a layer 144 of a cured coating composition.
The coating composition can include conventional metal oxide
pigments, and/or one or more solar reflective pigments, such as
titanium dioxide.
[0078] FIG. 7 is a schematic illustration of a reflective, solar
heat responsive roofing material 150 according to a seventh
embodiment of the present invention. In this embodiment, a membrane
152 is formed from a pair of continuous bituminous layers 154
sandwiching a reinforcing glass fiber scrim 156. The upper
bituminous layer 158 and lower bituminous layer 160 form continuous
phase in which is dispersed a discontinuous phase formed from
microcapsules 162 comprising phase change material 164 having a
fusion temperature between 50 degrees C. and 95 degrees C.
encapsulated in a flexible elastomeric wall 166. Partially embedded
in the upper surface of the upper bituminous layer 158 are a
plurality of roofing granules 170 comprising an inert mineral
material. The roofing granules 170 and the upper surface of the
upper layer 158 are coated with a layer 172 of a cured roof coating
composition. The roof coating composition includes one or more
solar reflective pigments, such as titanium dioxide, dispersed in
an elastomeric binder.
[0079] FIG. 8 is a schematic illustration of a solar heat
responsive roofing material 180 according to an eighth embodiment
of the present invention. In this embodiment, the roofing material
180 includes a bituminous membrane 182 reinforced with a scrim 184
formed from glass fibers. Partially embedded in the upper surface
186 of the bituminous membrane 182 are a plurality of composite
roofing granules 190 having nuclei 192 formed from capsules 194
including cores 196 of phase change material covered with an
exterior wall 198 bound together with a siliceous matrix 200, and
covered with a layer 202 of a cured coating composition in which
are dispersed conventional iron oxide pigments. The upper surface
of the upper layer 186 is coated with a layer 204 of a cured roof
coating composition. The roof coating composition includes one or
more solar reflective pigments, such as titanium dioxide, dispersed
in an elastomeric binder.
[0080] FIG. 9 is a schematic illustration of solar heat responsive
roofing material 210 according to a ninth embodiment of the present
invention. In this embodiment, the roofing material 210 includes a
bituminous membrane 212 reinforced with a scrim 214 formed from
glass fibers. Partially embedded in the upper surface 216 of the
bituminous membrane 212 are a plurality of composite roofing
granules 220 having nuclei 222 formed from capsules 224 including
cores 226 of phase change material covered with an exterior wall
228 bound together with a siliceous matrix 230, and covered with a
layer 232 of a cured coating composition including one or more
solar reflective pigments, such as titanium dioxide, dispersed in a
siliceous binder.
[0081] The PCM roofing granules of the present invention can be
employed in the manufacture of roofing products, such as asphalt
shingles, using conventional roofing production processes.
Typically, bituminous roofing products are sheet goods that include
a non-woven base or scrim formed of a fibrous material, such as a
glass fiber scrim. The base is coated with one or more layers of a
bituminous material such as asphalt to provide water and weather
resistance to the roofing product. One side of the roofing product
is typically coated with mineral granules to provide durability,
reflect heat and solar radiation, and to protect the bituminous
binder from environmental degradation. The PCM roofing granules of
the present invention can be mixed with conventional roofing
granules, and the granule mixture can be embedded in the surface of
such bituminous roofing products using conventional methods.
Alternatively, the PCM granules of the present invention can be
substituted for conventional roofing granules in the manufacture of
bituminous roofing products to provide those roofing products with
solar heat storage.
[0082] Bituminous roofing products are typically manufactured in
continuous processes in which a continuous substrate sheet of a
fibrous material such as a continuous felt sheet or glass fiber mat
is immersed or coated in a bath of hot, fluid bituminous coating
material so that the bituminous material saturates the substrate
sheet and coats at least one side of the substrate. The reverse
side of the substrate sheet can be coated with an anti-stick
material such as a suitable mineral powder or a fine sand. Roofing
granules are then distributed over selected portions of the top of
the sheet, and the bituminous material serves as an adhesive to
bind the roofing granules to the sheet when the bituminous material
has cooled. The sheet can then be cut into conventional shingle
sizes and shapes (such as one foot by three feet rectangles), slots
can be cut in the shingles to provide a plurality of "tabs" for
ease of installation, additional bituminous adhesive can be applied
in strategic locations and covered with release paper or release
film to provide for securing successive courses of shingles during
roof installation, and the finished shingles can be packaged. More
complex methods of shingle construction can also be employed, such
as building up multiple layers of sheet in selected portions of the
shingle to provide an enhanced visual appearance, or to simulate
other types of roofing products.
[0083] The bituminous material used in manufacturing roofing
products according to the present invention is derived from a
petroleum processing by-product such as pitch, "straight-run"
bitumen, or "blown" bitumen. The bituminous material can be
modified with extender materials such as oils, petroleum extracts,
and/or petroleum residues. The bituminous material can include
various modifying ingredients such as polymeric materials, such as
SBS (styrene-butadiene-styrene) block copolymers, resins, oils,
flame-retardant materials, stabilizing materials, anti-static
compounds, and the like. Preferably, the total amount by weight of
such modifying ingredients is not more than about 15 percent of the
total weight of the bituminous material. The bituminous material
can also include amorphous polyolefins, up to about 25 percent by
weight. Examples of suitable amorphous polyolefins include atactic
polypropylene, ethylene-propylene rubber, etc. Preferably, the
amorphous polyolefins employed have a softening point of from about
130 degrees C. to about 160 degrees C. The bituminous composition
can also include a suitable filler, such as calcium carbonate,
talc, carbon black, stone dust, or fly ash, preferably in an amount
from about 10 percent to 70 percent by weight of the bituminous
composite material.
[0084] Various modifications can be made in the details of the
various embodiments of the processes, compositions and articles of
the present invention, all within the scope and spirit of the
invention and defined by the appended claims.
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