U.S. patent application number 11/210490 was filed with the patent office on 2007-06-07 for roof surfacing having increased reflectance.
This patent application is currently assigned to Siplast, Inc.. Invention is credited to Kirk Goodrum, Tim Kersey.
Application Number | 20070128408 11/210490 |
Document ID | / |
Family ID | 38119114 |
Filed Date | 2007-06-07 |
United States Patent
Application |
20070128408 |
Kind Code |
A1 |
Goodrum; Kirk ; et
al. |
June 7, 2007 |
Roof surfacing having increased reflectance
Abstract
A roof surfacing having increased reflectance comprises a roof
membrane with a bituminous layer and a layer of generally flat
particles placed in a generally overlapping geometry so as to
substantially cover the bituminous layer. The composition of the
particles includes a polymer and a filler. The polymer may be
polyvinyl acetate (PVA), polyvinyl chloride (PVC), polyester,
acrylic, polymethylmethacrylate, or methylmethacrylate (MMA). The
filler may be calcium carbonate, dolomite, or barium sulfate. The
particles may further include a pigment, fire retardant, and/or
anti-microbial agent. A method of creating a roof surfacing having
increased reflectance includes creating a thin sheet of material
having increased reflectance, dividing that sheet into multiple
particles, feeding the particles through a hopper onto a curved
directional plate, and placing the particles on a roof membrane
having a molten bituminous layer in a generally horizontal
direction to create an overlapping, scaled appearance.
Inventors: |
Goodrum; Kirk; (Arkadelphia,
AR) ; Kersey; Tim; (Arkadelphia, AR) |
Correspondence
Address: |
AKIN, GUMP, STRAUSS, HAUER & FELD, L.L.P.
P.O. BOX 12870
SAN ANTONIO
TX
78212
US
|
Assignee: |
Siplast, Inc.
Irving
TX
|
Family ID: |
38119114 |
Appl. No.: |
11/210490 |
Filed: |
August 24, 2005 |
Current U.S.
Class: |
428/143 ;
428/141 |
Current CPC
Class: |
B32B 11/10 20130101;
B32B 2307/3065 20130101; B32B 2307/718 20130101; E04D 5/12
20130101; B32B 2307/416 20130101; Y10T 428/24372 20150115; Y10T
428/24355 20150115; B32B 2264/0242 20130101; B32B 2307/4026
20130101; B32B 2419/06 20130101; B32B 11/12 20130101; B32B
2264/0278 20130101; B32B 2309/105 20130101; D06N 5/00 20130101 |
Class at
Publication: |
428/143 ;
428/141 |
International
Class: |
E01F 9/04 20060101
E01F009/04 |
Claims
1. A roof surfacing having increased reflectance, comprising: a
roof membrane, having a bituminous layer; and a layer of generally
flat particles placed in generally overlapping relationship to each
other so as to substantially cover said bituminous layer.
2. The roof surfacing of claim 1, wherein said particles are
adhered to said roof surfacing by said bituminous layer.
3. The roof surfacing of claim 1, wherein said bituminous layer
comprises a material selected from the group of bitumen, modified
bitumen, tar, pitch, or asphalt.
4. The roof surfacing of claim 1, wherein said particles have a
mean width to thickness ratio of about 2:1 to about 50:1.
5. The roof surfacing of claim 1, wherein said particles have a
mean width of about 1/8 inch.
6. The roof surfacing of claim 1, wherein said particles comprise a
material having increased reflectance, comprising: a polymer
selected from the group consisting of polyvinyl acetate (PVA),
polyvinyl chloride (PVC), polyester, acrylic,
polymethylmethacrylate, and methylmethacrylate (MMA); and a filler
selected from the group consisting of calcium carbonate, dolomite,
and barium sulfate.
7. The roof surfacing of claim 6, wherein said particles further
comprise a pigment.
8. The roof surfacing of claim 6, wherein said particles further
comprise a fire retardant.
9. The roof surfacing of claim 6, wherein said particles further
comprise an anti-microbial agent.
10. The roof surfacing of claim 7, wherein said pigment comprises
titanium dioxide.
11. A roof surfacing having increased reflectance, comprising: a
roof membrane, having a bituminous layer; and a layer of particles,
having a mean width of about 1/8 inch and a mean width to thickness
ratio of about 2:1 to about 50:1, placed in generally overlapping
relationship to each other so as to substantially cover said
bituminous layer.
12. The roof surfacing of claim 11, wherein said particles comprise
a material having increased reflectance, comprising: a polymer
selected from the group consisting of polyvinyl acetate (PVA),
polyvinyl chloride (PVC), polyester, acrylic,
polymethylmethacrylate, and methylmethacrylate (MMA); and a filler
selected from the group consisting of calcium carbonate, dolomite,
and barium sulfate.
13. The roof surfacing of claim 12, wherein said particles further
comprise a pigment.
14. The roof surfacing of claim 12, wherein said particles further
comprise a fire retardant.
15. The roof surfacing of claim 12, wherein said particles further
comprise an anti-microbial agent.
16. The roof surfacing of claim 13, wherein said pigment comprises
titanium dioxide.
17. A method of making a roof surfacing having increased
reflectance, comprising the steps of: creating a sheet of material
having an increased reflectance; dividing said sheet into a
plurality of generally flat particles; feeding said particles
through a hopper onto a curved directional plate; depositing said
particles onto a molten bituminous layer of a roof membrane in a
generally horizontal direction to create an overlapping, scaled
appearance.
18. The method of claim 17, wherein said directional plate orients
said particles in a generally horizontal direction.
19. The method of claim 17, further comprising the step of
solidifying said bituminous layer to adhere said particles to said
roof surfacing.
20. The method of claim 17, wherein said particles have a mean
width to thickness ratio of about 2:1 to about 50:1.
21. The method of claim 17, wherein said particles have a mean
width of about 1/8 inch.
22. The method of claim 17, wherein said sheet has a thickness of
about 0.1 to about 0.4 mm.
23. The method of claim 17, wherein said sheet comprises: a polymer
selected from the group consisting of polyvinyl acetate (PVA),
polyvinyl chloride (PVC), polyester, acrylic,
polymethylmethacrylate, and methylmethacrylate (MMA); and a filler
selected from the group consisting of calcium carbonate, dolomite,
and barium sulfate.
24. The method of claim 23, wherein said sheet further comprises a
pigment.
25. The method of claim 23, wherein said sheet further comprises a
fire retardant.
26. The method of claim 23, wherein said sheet further comprises an
anti-microbial agent.
27. The method of claim 24, wherein said pigment comprises titanium
dioxide.
28. A composition of matter suitable for forming particles for use
in a roof surfacing having increased reflectance, comprising: a
polymer selected from the group consisting of polyvinyl acetate
(PVA), polyvinyl chloride (PVC), polyester, acrylic,
polymethylmethacrylate, and methylmethacrylate (MMA); and a filler
selected from the group consisting of calcium carbonate, dolomite,
and barium sulfate.
29. The composition of matter of claim 28, wherein said composition
is about 10 to about 100 percent by weight polymer and about 0 to
about 90 percent by weight filler.
30. The composition of matter of claim 28, further comprising a
pigment.
31. The composition of matter of claim 28, further comprising a
fire retardant.
32. The composition of matter of claim 28, further comprising an
anti-microbial agent.
33. The composition of matter of claim 30, wherein said pigment
comprises titanium dioxide.
34. The composition of matter of claim 30, wherein said composition
is about 10 to about 100 percent by weight polymer, about 0 to
about 90 percent by weight filler, and about 0 to about 10 percent
by weight pigment.
35. The composition of matter of claim 30, wherein said composition
is about 10 to about 15 percent by weight polymer, about 75 to
about 85 percent by weight filler, and about 5 to about 10 percent
by weight pigment.
Description
FIELD OF THE INVENTION
[0001] This invention relates to roofing materials and surfaces,
and more particularly to a roof surfacing having increased solar
reflectance.
BACKGROUND OF THE INVENTION
[0002] It has become desirable in recent years to create roof
surfaces having increased solar reflectance to reduce the
temperature of roofs, reduce the amount of energy required to cool
the enclosed facility, and reduce ambient heat in densely populated
areas. In fact, various jurisdictions have enacted laws and
ordinances setting mandatory levels of roof surface reflectance.
Traditional roofing materials are comprised of a roof membrane
containing bitumen and granules embedded in the surface of the
membrane to protect the bitumen from damaging ultraviolet
radiation. The bituminous layer is naturally black, making it
necessary to cover as much of the bituminous layer as possible to
create a reflectance of 0.70 or greater, as defined by ASTM methods
E 903 and E 1918. Even using white granules in manufacturing a
traditional granular surfaced roof membrane creates a reflectance
value no greater than 0.32. The difficulty is that traditional
roofing granules are processed from naturally occurring minerals
that are crushed and sized, resulting in irregular surfaces and
shapes. These irregular shapes make complete coverage of the black
bituminous layer of the roof membrane virtually impossible.
Further, the irregular surfaces of the granules result in some
incident light energy being reflected between the granules, thereby
trapping incident energy in the roof surfacing, decreasing
reflectance, and damaging the underlying bituminous layer.
[0003] Complete, or near-complete, coverage of the black bituminous
layer is currently achieved by various methods, all of which have
significant drawbacks. Roofing material manufacturers have achieved
a high level of reflectance by applying a white film to the surface
of the roof membrane, by applying a reflective coating either in
the field or at the factory, or by applying a coated fiberglass mat
to the surface of the roof membrane. These methods all call for
extra production steps, either at the manufacturing facility or in
the field, which significantly increase labor and raw materials
costs. Further, because these continuous coatings or films are
applied to an underlying roof membrane with different physical
properties, adhesion problems frequently occur between the coatings
or films and the underlying roof membrane. For example, the coating
or film and the roof membrane may have different coefficients of
thermal expansion, meaning that the two materials will expand and
contract at different rates when subjected to thermal oscillations.
This disparity causes stress at the bond plane between the two
materials, which may eventually cause the two materials to
separate, or delaminate.
[0004] Adhesion problems are also brought about because roof
membranes are typically stored and transported in a rolled,
cylindrical form. When a coated roof membrane is wound around a
cylindrical core, the coating or film and the underlying roof
membrane are at different radii from the center. This means that
the coating or film and the underlying roof membrane will have
different circumferences, causing at least one of the materials to
stretch or compress in order to maintain the bond between the two.
This stretching or compression creates stress at the bond plane
between the two materials, which may eventually lead to
delamination of the two materials in storage.
[0005] Various roof surfaces have been proposed to increase
reflectance without the delamination problems detailed above. By
way of example, published U.S. patent application Ser. Nos.
10/421,386 and 10/683,536, both assigned to The Garland Company,
disclose a granular material and method of applying the granular
material to the surface of roofing materials resulting in increased
reflectivity. But the irregularities in the granular shape of The
Garland Company's surface material prevents complete coverage of
the underlying bituminous layer of the roof membrane, thereby
limiting the reflectance this material can achieve.
[0006] Flat particles have been used in roof surfacing to effect a
more complete coverage of the bituminous layer for purposes other
than increasing reflectance. For instance, published U.S. patent
application Ser. No. 10/274,717 by Kiik et al. discloses the use of
metal flakes on a roof surface to improve durability and aesthetic
qualities of the roof. But metal is susceptible to oxidation upon
exposure to various weather conditions, leading to sometimes
drastic changes in the appearance of the roof surface, and metal is
a relatively expensive roofing material. Further, metal is a good
thermal conductor, meaning that solar energy not reflected by the
metallic flakes will likely be transferred to the underlying
bituminous layer as heat, which can accelerate the destruction of
the bitumen and shorten the useful life of the roof membrane.
[0007] What is needed in the roofing industry is a roof surfacing
having increased reflectance, reduced incidence of delamination,
low thermal conductance, high opacity to ultraviolet radiation,
reduced weight, and good weathering characteristics.
SUMMARY OF THE INVENTION
[0008] In accordance with one aspect of the present invention, a
roof surfacing comprises a roof membrane and a plurality of
generally flat particles overlying the roof membrane. The roof
membrane has a bituminous layer to which the flat particles are
adhered. The discontinuous roof surfacing material provided by the
present invention avoids the delamination problems noted in the
prior art. The flat particles may be arranged in a generally
overlapping geometry to substantially cover the bituminous layer.
The roof surfacing exhibits increased reflectance because the flat
particles have a regular surface and an increased ability to cover
the black bituminous layer.
[0009] In accordance with a further aspect of the present
invention, the flat particles comprise a composition exhibiting a
high reflectance, namely a polymer and a filler, wherein the
polymer may be selected from the group consisting of polyvinyl
acetate (PVA), polyvinyl chloride (PVC), polyester, acrylic,
polymethylmethacrylate, and methylmethacrylate (MMA) and the filler
may be selected from the group consisting of calcium carbonate,
dolomite, and barium sulfate. Advantageously, the particles may
further comprise a pigment, which is preferably titanium dioxide.
In an even more beneficial aspect of the invention, the particles
may further comprise a fire retardant.
[0010] In accordance with an even further aspect of the invention,
a method for constructing a roof surfacing comprises forming a
sheet of material having an increased reflectance; dividing the
sheet into generally flat particles; feeding the particles through
a hopper onto a curved directional plate; and depositing the
particles onto a molten bituminous layer of a roof membrane.
Preferably, the particles may be deposited in an overlapping,
generally horizontal geometry, creating a scaled appearance. It may
also be advantageous for the particles to have a mean width to
thickness ratio of about 2:1 to about 50:1.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The foregoing summary, as well as the following detailed
description of preferred embodiments of the invention, will be
better understood when read in conjunction with the appended
drawings. For the purpose of illustrating the invention, three
embodiments that are presently preferred are shown in the drawings.
It should be understood, however, that the invention is not limited
to the precise arrangements and instrumentalities shown. In the
drawings:
[0012] FIG. 1 is a top view of a roof surfacing in accordance with
the present invention.
[0013] FIG. 2 is a cross-sectional view of a roof surfacing in
accordance with the present invention, taken along line 2-2 of FIG.
1.
[0014] FIG. 3 is a cross-sectional view of a prior art granular
surfaced roof membrane.
[0015] FIG. 4 is a detail view of an individual, exemplary particle
in accordance with the present invention.
[0016] FIG. 5 is a schematic diagram illustrating a method of
constructing the roof surfacing in accordance with the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] Referring now to the drawings, and to FIGS. 1 and 2 in
particular, a roof surfacing 16 in accordance with one embodiment
of the present invention is illustrated. The roof surfacing 16
includes a roof membrane 14 having a bituminous layer 15, and a
plurality of generally flat particles 10 overlying the roof
membrane 14, secured to the roof membrane 14 by the bituminous
layer 15. The roof membrane 14 is of well-known construction and
typically comprises a woven, nonwoven, or composite fabric coated
in a bituminous layer 15. The bituminous layer 15 can be any of the
water-resistant materials known in the roofing industry, including,
but without limitation, those materials containing or derived from
bitumen, modified bitumen, tar, pitch, or asphalt.
[0018] Turning now to FIGS. 2 and 3, the particles 10 preferably
overlap each other to cover the bituminous layer 15 more completely
than can be achieved with irregularly shaped granules 27. Also, the
generally flat surfaces of the particles 10 reduce the amount of
incident energy 22 that is trapped between particles 10, allowing
more energy 22 to be effectively reflected away from the surface
16. The combination of greater coverage of the bituminous layer 15
and a more uniform surface increases reflectance and minimizes the
amount of solar energy that is transferred to the bituminous layer
15 of the roof surfacing 16. The reduced effect of solar energy 22
on the bitumen 15 can be seen in an increased lifespan of the roof
membrane 14, lowered energy costs to cool the enclosed structure,
and a cooler roof surface 16.
[0019] As shown in FIG. 5, the inventive roof surfacing 16 is
manufactured by beginning with a thin sheet 51 of the highly
reflective material. The thickness 33 of this sheet preferably
ranges from about 4 to about 15 mils (about 0.1 to about 0.4 mm).
This sheet 51 of material is divided into multiple particles 10.
The particles 10 need not be identical in size or shape or of any
particular size or shape. The preferred width 32 of these particles
is about 1/8 inch, but a mean width 32 to thickness 33 ratio of
about 2:1 to about 50:1 produces the desired improvements of the
present invention, independent of any particular width 32 of the
particles 10. The generally flat particles 10 are placed in a
hopper 53 for eventual deposition onto the roof membrane 14. The
flat particles 10 are fed from the hopper 53 onto a curved
directional plate 56, which serves to orient the particles 10 in a
generally horizontal direction. The generally flat geometry of the
particles 10 allows for some degree of overlap between the
particles 10 as they are deposited onto the bituminous layer 15 of
the roof membrane 14. This results in a horizontally scaled
appearance. The particles 10 are not deposited in any particular
vertical configuration. Because the particles 10 are deposited on
the bituminous layer 15 while the bituminous layer 15 is in its
warm, molten state, the particles 10 become partially embedded in
the bituminous layer 15. Upon solidification of the bituminous
layer 15, the particles 10 are securely adhered to the roof
membrane 14.
[0020] The flat particles 10 may comprise any combination of a
polymer and a filler, where the polymer may be polyvinyl acetate
(PVA), polyvinyl chloride (PVC), polyester, acrylic,
polymethylmethacrylate, or methylmethacrylate (MMA) and the filler
may be calcium carbonate, dolomite, or barium sulfate.
Additionally, the particles 10 may contain one or more pigments.
Currently, the preferred pigment is titanium dioxide for its
ultraviolet protective properties, but any other pigment may be
added to the particles 10 in lieu of or in addition to titanium
dioxide to impart various colors to the reflective roof surface.
Further, the particles 10 may contain other beneficial additives,
such as, but not by way of limitation, fire retardants or
anti-microbial agents.
[0021] A currently preferred embodiment combines PVA, barium
sulfate, and titanium dioxide, with PVA comprising about 10 to
about 15 percent of the composition by weight, barium sulfate
comprising about 75 to about 85 percent of the composition by
weight, and titanium dioxide comprising about 5 to about 10 percent
of the composition by weight. The PVA compound is currently
preferred due to its ready availability and low cost. It is
believed that MMA may be an even more preferable polymer component
due to its ability to withstand harsh weather conditions.
[0022] Another currently preferred embodiment exhibits improved
weathering properties by combining acrylic, calcium carbonate, and
titanium dioxide, with acrylic comprising about 10 to about 15
percent of the composition by weight, calcium carbonate comprising
about 75 to about 85 percent of the composition by weight, and
titanium dioxide comprising about 5 to about 10 percent of the
composition by weight.
[0023] It will be appreciated by those skilled in the art that
changes could be made to the embodiments described above without
departing from the broad inventive concept thereof. By way of
example, the flat particles could be of uniform size and shape.
Alternatively, the flat particles could be adhered to roof surfaces
other than traditional roof membranes having a bituminous layer,
using any adhesion method known in the art. It will be understood,
therefore, that this invention is not limited to the particular
embodiments disclosed, but it is intended to cover modifications
within the spirit and scope of the present invention as defined by
the appended claims.
* * * * *