Note: Descriptions are shown in the official language in which they were submitted.
CA 02593834 2007-07-05
ROOFING PRODUCTS CONTAINING PHASE CHANGE MATERIALS
BACKGROUND OF THE INVENTION
1. Field of the Invention.
The present invention relates to roofing products, and processes for making
such
products.
2. Brief Description of the Prior Art.
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.
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.
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. Patent
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.
Roofing granules typically comprise crushed and screened mineral materials,
which are subsequently coated with a binder containing one or more coloring
pigments,
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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.
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.
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 C on the surface of black roofing shingles on a sunny day with 21
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.
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.
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Another approach is provided by U.S. Patent 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 Al 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 Al 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 Al 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 Al 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.
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.
U.S. Patent 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.
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
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polyester resin or styrene monomer, a PCM component, and a granular base
medium
such as a granular-sized stone.
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
The present invention provides roofing materials and roofs formed therefrom
that
have improved resistance to thermal stresses and which simultaneously provide
an
attractive appearance.
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.
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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.
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
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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.
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.
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
Figure 1 is a schematic illustration of a solar heat responsive roofing
material
according to a first embodiment of the present invention.
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Figure 2 is a schematic illustration of a solar heat responsive roofing
material
according to a second embodiment of the present invention.
Figure 3 is a schematic illustration of a solar heat responsive roofing
material
according to a third embodiment of the present invention.
Figure 4 is a schematic illustration of a solar heat responsive roofing
material
according to a fourth embodiment of the present invention.
Figure 5 is a schematic illustration of a solar heat responsive roofing
material
according to a fifth embodiment of the present invention.
Figure 6 is a schematic illustration of a solar heat responsive roofing
material
according to a sixth embodiment of the present invention.
Figure 7 is a schematic illustration of a solar heat responsive roofing
material
according to a seventh embodiment of the present invention.
Figure 8 is a schematic illustration of a solar heat responsive roofing
material
according to a eighth embodiment of the present invention.
Figure 9 is a schematic illustration of a solar heat responsive roofing
material
according to a ninth embodiment of the present invention.
DETAILED DESCRIPTION
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.
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.
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
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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.
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.
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
(H4P206, 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
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(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(NO3)23H20
(melting point
51 degrees C, latent heat of fusion 104 kJ/kg), Na(NO3)2 6H20 (melting point
53 degrees
C, latent heat of fusion 158 kJ/kg), Zn(NO3)2.2H20 (melting point 55 degrees
C, latent
heat of fusion 68 kJ/kg), FeC13.21-120 (melting point 56 degrees C, latent
heat of fusion 90
kJ/kg), Co(NO3)2-6H20 (melting point 57 degrees C, latent heat of fusion 115
kJ/kg),
Ni(NO3)2=6H20 (melting point 57 degrees C, latent heat of fusion 168 kJ/kg),
MnC12.4H20
(melting point 58 degrees C, latent heat of fusion 151 kJ/kg), CH3COONa3H20
(melting
point 58 degrees C, latent heat of fusion 270-290 kJ/kg), LiC2H30221120
(melting point
58 degrees C, latent heat of fusion 251-377 kJ/kg), MgC124H20 (melting point
58.0
degrees C, latent heat of fusion 178 kJ/kg), Na0H.H20 (melting point 58
degrees C,
latent heat of fusion 272 kJ/kg), Cd(NO3)24H20 (melting point 59 degrees C,
latent heat
of fusion 98 kJ/kg), Cd(NO3)2-1H20 (melting point 59.5 degrees C, latent of
fusion 107
kJ/kg), Fe(NO3)2=6H20 (melting point 60 degrees C, latent of fusion 125
kJ/kg),
NaAl(SO4)2.12H20 (melting point 61 degrees C, latent of fusion 181 kJ/kg),
FeSO4 7H20
(melting point 64 degrees C, latent of fusion 200 kJ/kg), Na3PO4 12H20
(melting point 65
degrees C, latent of fusion 168 kJ/kg), Na2B407 10H20 (melting point 68
degrees C),
Na3PO4 12H2O (melting point 69 degrees C), LiCH3C00.2H20 (melting point 70
degrees
C, latent of fusion 150-251 kJ/kg), Na2P20210H20 (melting point 70 degrees C,
latent of
fusion 186-230 kJ/kg), Al(NO3)2.9H20 (melting point 72 degrees C, latent of
fusion 155-
176 kJ/kg), Ba(OH)2 8H20 (melting point 78 degrees C, latent of fusion 265-280
kJ/kg),
Al2(SO4)31 8H20 (melting point 88 degrees C, latent of fusion 218 kJ/kg),
Sr(OH)28H20
(melting point 89 degrees C, latent of fusion 370 kJ/kg), Mg(NO3)2 6H20
(melting point
89-90 degrees C, latent of fusion 162-167 kJ/kg), KA1(SO4)212H20 (melting
point 91
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degrees C, latent of fusion 184 kJ/kg), and (NH4)Al(SO4)6H20 (melting point 95
degrees
C, latent of fusion 269 kJ/kg). Suitable eutectic mixtures include mixtures of
13-16
weight percent L1NO3, 19-21 weight percent KNO3, and 63-68 weight percent
Mg(NO3)26H20 (melting point 52 degrees C), mixtures of 61.5 weight percent
Mg(NO3)6H20 and 38.4 weight percent NH4NO3 (melting point 52 degrees C, latent
heat
of fusion 125.5 kJ/kg), mixtures of 58.7 weight percent Mg(NO3)6H20 and 41.3
weight
percent MgC126H20 (melting point 59 degrees C, latent heat of fusion 132.2
kJ/kg),
mixtures of 53 weight percent Mg(NO3)6H20 and 47 weight percent Al(NO3)2.9H20
(melting point 61 degrees C, latent heat of fusion 148 kJ/kg), mixtures of 59
weight
percent Mg(NO3)6H20 and 41 weight percent Mgf3r28H20 (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 LiNO3, 6-8 percent by weight NaNO3,
and 80-84
percent by weight Mg(NO3)2 6H20 (melting point 67 degrees C), mixtures of 79
weight
percent AICI3, 17 weight percent NaCI, and 4 weight percent ZrC12 (melting
point 68
degrees C, latent heat of fusion 234 kJ/kg), mixtures of 66 weight percent
AlC13, 20
weight percent NaCI, and 14 weight percent KCI (melting point 70 degrees C,
latent heat
of fusion 209 kJ/kg), mixtures of 66.6 weight percent NH2CONH2 and 34.4 weight
percent NH4Br (melting point 76 degrees C, latent heat of fusion 151 kJ/kg),
mixtures of
25 weight percent L1NO3, 65 weight percent NH4NO3, and 10 weight percent NaNO3
(melting point 80.5 degrees C, latent heat of fusion 113 kJ/kg), mixtures of
60 weight
percent AlC13, 26 weight percent NaCI, and 14 weight percent KC1 (melting
point 93
degrees C, latent heat of fusion 213 kJ/kg), and mixtures of 66 weight percent
AlC13 and
34 weight percent NaCI (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-
methy1-
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
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poly(vinyl ethyl ether), poly(vinyl n-butyl ether) and polychloroprene,
polyethylene glycols
such as Carbowax FM 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).
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.
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.
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. Patents Nos. 6.156,245, 6,797,277, and 6,861,145.
The microencapsulation of phase change material is well-known in the art, and
is
disclosed for example, in U.S. Patent 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).
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
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CA 02593834 2007-07-05
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.
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.
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. Patent 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. Patent 6,063,312.
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
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and the diluent is encapsulated. The diluent can be selected so that it can
escape
through the microcapsule walls after formation of the microcapsules.
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.
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.
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.
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
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CA 02593834 2007-07-05
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.
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, DE 19880.
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.
When a mixed algaecide is employed, the algae-resistant material preferably
comprises a mixture of cuprous oxide and zinc oxide.
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, OH 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.
Roofing granules typically comprise crushed and screened mineral materials,
which are subsequently coated with a binder containing one or more coloring
pigments,
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CA 02593834 2014-02-21
'4
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.
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.
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. Patents 2,591,149, 2,614,051,
2,898,232
and 2,981,636, 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. Patent 6,143,318,
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.
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CA 02593834 2014-02-21
4
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.
Examples of clays that can be employed in preparing PCM roofing granules fo
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.
In one presently preferred embodiment, the roofing material of the present
invention includes at least one solar heat reflective material.
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
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
The solar heat-reflective pigment can also comprise a near infrared-reflecting
composite pigment such as disclosed in U.S. Patent 6.521,038.
25 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,
Examples of near infrared-reflective pigments available from the Shepherd
Color
Company, Cincinnati, OH, include Arctic Black 100909 (chromium green-black),
Black
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CA 02593834 2007-07-05
411 (chromium iron oxide), Brown 12 (zinc iron chromite), Brown 8 (iron
titanium brown
spinel), and Yellow 193 (chrome antimony titanium).
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.
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 Talzhu 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).
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 Iriodie 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 A1203 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 Si02
platelets
coated with metal oxides, including ColorStream F 20-00 WNT autumn mystery and
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CA 02593834 2007-07-05
ColorStream F 20-07 WNT viola fantasy; and ultra interference pigments based
on TiO2
and mica.
Examples of mirrorized silica pigments that can be employed in the process of
the present invention include pigments such as Chrom BriteTM CB4500, available
from
Bead Brite, 400 Oser Ave, Suite 600, Hauppauge, N.Y. 11788.
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 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.
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.
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.
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 crn. and the average size of the PCM
microcapsules 16 is about 0.03 cm.
Figure 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
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CA 02593834 2007-07-05
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.
Figure 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.
Figure 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.
Figure 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.
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CA 02593834 2007-07-05
Figure 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.
Figure 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.
Figure 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
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CA 02593834 2007-07-05
cured roof coating composition. The roof coating composition includes one or
more
solar reflective pigments, such as titanium dioxide, dispersed in an
elastomeric binder.
Figure 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.
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.
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
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CA 02593834 2014-02-21
4
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.
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.
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
of the invention and defined by the appended claims.
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