Note: Descriptions are shown in the official language in which they were submitted.
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BUILDING PANEL HAVING AT LEAST TWO PANEL DOMAINS OF DIFFERENT
AVERAGE COMPRESSIVE STRENGTH
The present invention relates to a building panel having
at least two panel domains of different average compressive
strengths. The panel is useful for filling cavities having
non-uniform dimensions, having obstacles disposed therein, or
both.
Building structures typically contain a framework
1o defining a plurality of cavities with the framework acting as
cavity walls. For instance, buildings often have a wood or
metal framework comprised of studs and joists spaced a
certain distance apart. The studs and joists act as cavity
walls. A distance between two studs or joists defines a
i5 cavity spacing and a volume between two studs or two joists
defines a cavity. It is often desirous to insert within a
cavity a material, such as a thermal insulator. However,
cavities come in a variety of sizes and shapes and may have
obstacles, such as electrical conduit or plumbing pipes,
20 disposed therein. Fitting panels tightly into cavities of
varying dimensions and containing a variety of obstacles
requires either manufacturing a specific panel for each
different cavity or the use of a panel that is sufficiently
flexible to conform to different cavity sizes, shapes and
25 obstacles.
Common materials for filling cavities include fibrous
materials and polymeric foam. Fibrous materials, such as
glass wool and cellulose fiber, typically require special
care during installation since inhalation and handling of
30 fibers is often irritating. Fibrous batting is also
especially flexible, allowing the batting to buckle, sag, or
droop when spanning a wide cavity such as between rafter
joists. Rigid polymeric foam, such as polystyrene (PS) and
rigid polyurethane foam, is attractive as thermal insulation
35 in cavities, but performs less than optimally in conforming
to various cavity sizes, shapes and obstacles. Rigid
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polymeric foam typically requires cutting to conform to a
specific cavity. Flexible polymeric foam, such as flexible
polyurethane foam (FPU), conforms more readily to cavity
variations than a rigid foam board. Unfortunately, the
flexibility also allows the foam to buckle, sag or droop when
spanning a wide cavity such as between rafter joists.
Ideally, a panel for fitting into cavities has a
combination of flexible properties for conforming to cavity
shapes, sizes and obstacles and rigid properties to hinder
1o buckling and sagging of the panel when disposed within a
cavity. United States patent application 09/706,110 ('110)
discloses one such panel comprising a combination of hollow
and solid coalesced foam strands (see, page 14 lines 7-17).
A need exists for a panel that can fit into cavities
having various sizes, shapes and obstacles yet does not
suffer from handicaps attributed to fibrous materials, rigid
foam, or flexible polymeric foam and which is free of a
combination of hollow and solid foam strands.
In a first aspect, the present invention is a building
2o panel comprising at least two panel domains, wherein each
panel domain has an essentially homogeneous compressive
strength and an average compressive strength; wherein said
panel: (a) has at least two panel domains having different
average compressive strengths; and (b) is essentially free of
a combination of hollow and solid foam strands; and wherein,
if said panel has at least two adjacent panel domains
containing fibrous material with a fiber orientation, the
fiber orientation of one panel domain is non-orthogonal to
the fiber orientation of at least one adjacent panel domain.
3o A particularly useful variation of the first aspect
comprises at least one conformable panel domain that, when
compressed, reduces at least one dimension of the panel
thereby allowing insertion of the panel into a cavity;
wherein the panel has a compressive recovery that causes
frictional retention of the panel within the cavity. That
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is, the conformable panel domain presses against a cavity
wall of a cavity with sufficient pressure to retain the
building panel within the cavity due to friction between the
cavity wall and conformable panel.
s Another useful variation of the first aspect contains a
conformable panel domain within the panel; wherein said
conformable panel domain allows the panel to reversibly bend
from a planar to a non-planar configuration.
In a second aspect, the present invention is a method
i0 for at least partially filling a cavity comprising inserting
at least one panel within the cavity, wherein at least one
inserted panel is the panel of the first aspect.
The present invention meets a need by providing a panel
that can fit into cavities having various sizes, shapes and
i5 obstacles yet does not suffer from handicaps attributed to
fibrous materials, rigid foam, or flexible polymeric foam and
which is free of hollow and solid foam stands.
Figure (FIG) 1 shows a panel comprising two panel
domains.
2o FIGS 2a, 2b, and 2c show an example of a panel inserting
into a cavity by reversibly bending from a planar into a non-
planar configuration.
FIG 3a shows a panel having a conformable panel domain
around the perimeter of the panel.
25 FIG 3b shows a panel having multiple conformable panel
domains around the perimeter of the panel.
FIGs 4a and 4b show an end-on view of two panels, one
with a tongue profile and another with a groove profile,
connectively inserting into a cavity.
3o FIGS 5a and 5b show a panel of the present invention
working together with a panel having a single panel domain to
span a cavity.
The present invention relates to a building panel. A
"building panel" refers to a single article useful in
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fabricating buildings and structures containing cavities.
Herein, "building panel" and "panel" are interchangeable.
A building panel can be any shape or dimension that has
two opposing surfaces, at least one of which is a "primary
face". The primary face of a building panel has a surface
area equal to that of the highest surface area face on the
panel. A building panel may have two primary faces as long
as they are opposing and not adjoining. A primary face is
desirably a square or rectangle, although it may be any
shape, including circular. Building panels having a square
or rectangular primary face are square or rectangular
building panels, respectively. Preferably, a primary face is
parallel to its opposing face. The face or faces joining a
primary face to its opposing face are minor faces, forming a
i5 perimeter around the building panel. Examples of minor faces
include opposing ends and opposing edges of a square or
rectangular building panel.
"Panel thickness" is a perpendicular distance between a
primary face and its opposing face. The panel thickness at
2o any point on a primary surface of the building panel is
preferably one centimeter (cm) or greater, more preferably 2
cm or greater and may be 5 cm or greater, 10 cm or greater,
even 20 cm or greater. There is no known functional limit as
to how thick a building panel may be. Building panels having
25 a panel thickness less than one cm tend to be too thin to
span a cavity width without buckling, sagging, or both.
A building panel may have contours on one or more
surface. For example, a primary surface may have a
decorative design or a functional contour, such as cone-like
30 protrusions for acoustical attenuation. The building panel
may include grooves to facilitate conforming around obstacles
within a cavity or to facilitate bending of the panel.
Building panels desirably, though not necessarily, have
an essentially uniform panel thickness. Herein, a building
35 panel has an essentially uniform panel thickness if a
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difference in panel thickness at any two points on a primary
surface of a building panel is less than 10 percent (%) of an
average of the panel thickness at those two points or 5
millimeters (mm), whichever is greater. Preferably, the
building panel has a panel thickness difference of less than
3 mm, more preferably less than 2 mm between any two points
in the building panel.
A building panel of the present invention further
comprises at least two panel domains. A "panel domain" is a
section of a building panel that extends a building panel's
length, width, thickness, or a combination thereof. A panel
domain typically contains at least 1 percent, preferably at
least 2 percent, more preferably at least 5 percent, still
more preferably at least 10 percent and less than 100 percent
of a building panel's volume. Examples of suitable panel
domains include bands, strips, plugs (such as cylindrical
plugs extending the thickness of a building panel) or a
combination thereof. Preferably, panel domains are "bands".
Bands are panel domains that traverse a primary face of a
2o building panel. Desirably, a band also extends the thickness
of the panel. For example, a band may extend through the
panel thickness and extend to opposing ends (the length) of a
rectangular building panel. Panel domains may have any shape
and size and may differ in size, shape and physical
properties within a building panel. Preferably, at least one
panel domain, more preferably at least two panel domains,
more preferably all panel domains in a building panel have a
thermal conductivity of 0.1 Watt per meter-Kelvin (W/m*K) or
less, more desirably 0.065 W/m*K or less, most desirably
0.045 W/m*K or less. Determine thermal conductivity
according to ASTM method C-518-98.
Each panel domain has an essentially homogeneous
compressive strength and an average compressive strength.
"Essentially homogeneous compressive strength" means that any
section of the panel domain containing 20 percent of the
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panel domain volume has an average compressive strength in
any direction within 20 percent, preferably within 10 percent
of any other section of similar dimensions of the panel
domain containing 20 percent of the panel domain volume that
is compressed in the same direction and orientation. Measure
compressive strength values according to American Society for
Testing and Materials (ASTM) method D1621 unless otherwise
noted. "Average compressive strength" is the average
compressive strength over a compression range of 0-50
i0 percent, more preferably over a compression range of 0-80
percent. Herein, ranges include boundary values unless
otherwise stated.
Panel domains may be made of wood, metal, glass, rubber,
fibrous materials, inorganic foams, organic foams, and
i5 combinations thereof.
Examples of fibrous materials include fiber batting,
glass wool, mineral wool, polymeric fiber batting,
carbonaceous fibers, and rock wool. Building panels may
comprise at least two adjacent domains containing fibrous
2o material provided that if the fibrous material has a fiber
orientation, the fiber orientation of one domain is non-
orthogonal to the fiber orientation in at least one adjacent
domain. For example, United States Patent 4,025,680
discloses a fibrous thermal insulation comprising a plurality
25 of abutting parallel strips of fiber with the fiber
orientation in the strips alternating at right angles in the
adjacent strips (see, column 2 lines 5-11). Such a material
is not within the scope of the present invention since the
fiber orientation of each strip (or panel domain) is at a
3o right angle (orthogonal) to the fiber orientation of each
adjacent strip.
Preferably, at least one panel domain is free of fibrous
materials, more preferably the entire building panel is free
of fibrous materials. Still more preferably, at least one
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panel domain is a polymeric foam; most preferably all panel
domains in a building panel comprise polymeric foam.
Suitable polymeric foams include those containing one or
more of the following: polystyrene (PS) polymers and
copolymers; polyesters, polyolefins such as polyethylene
(PE), polypropylene (PP), PE copolymers such as
ethylene/styrene interpolymers,(ESI), and PP copolymers; and
polyurethane. Polymeric foams can contain a blend of
polymers, such as PP and PE blends.
1o Polymeric foams preferably have a density of 100
kilograms per cubic meter (kg/m3) or less, more preferably 50
kg/m3 or less. Foams having a density of greater than 100
kg/m3 generally have undesirable thermal insulating
properties. Foams generally have a density greater than 5
i5 kg/m3.
Polymeric foams have an average cell diameter.
Determine average cell diameter by measuring cell diameters
on a cross-section of a foam. The average cell diameter for
the foam is an average diameter for 20 or more randomly
2o selected cell cross-sections on the foam cross-section. The
diameter of non-spherical cells is the average of the longest
and shortest chord through the center of the cell cross-
section. View the foam cross-section using optical or
electron microscopy. Polymeric foams useful in this
25 invention preferably have an average cell diameter of 0.01 mm
or greater, more preferably 0.1 mm or greater, still more
preferably, 0.3 mm or greater. Preferably, the average cell
diameter is 10 mm or less, more preferably 4 mm or less,
still more preferably 2 mm or less. A foam that has an
3o average cell diameter below 0.01 mm tends to have an
undesirably high density. A foam that has an average cell
diameter greater than 10 mm tends to be a poor thermal
insulator.
Building panels of the present invention comprise at
35 least two panel domains that have differ in average
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compressive strength. Measure compressive strength with
similar panel domain sections that are of similar size and
shape and by compressing in the same direction and
orientation. Preferably, the two panel domains differ in
average compressive strength when compressed in a dimension
corresponding to a building panel's width. Desirably, the
two panel domains differ in average compressive strength by
at least 5 percent, preferably at least 10 percent, more
preferably at least 25 percent, and can differ in average
1o compressive strength by 50 percent or more, 100 percent or
more, even 200 percent or more.
Desirably, at least one panel domain is conformable. A
conformable panel domain is compressible and resilient,
thereby imparting a compressibility and compressive recovery
to the building panel. A conformable panel domain is
advantageously smaller in the dimension of compression than
any other dimension so as to hinder buckling of the panel
domain during compression.
Compressibility at 10 percent compression characterizes
2o the compressibility of a panel domain. A conformable panel
domain preferably has a compressive strength at 10 percent
compression of 0.1 kiloPascals (kPa) or more, more preferably
0.2 kPa or more, and still more preferably 0.3 kPa or more
and 200 kPa or less, more preferably 50 kPa or less, still
more preferably 20 kPa or less. A panel domain having a
compressive strength less than 0.1 kPa typically lacks
sufficient durability while a panel domain having compressive
strength greater than 200 kPa is generally too difficult to
compress.
Percent recovery from 50 percent compression
characterizes the resiliency of a panel domain. Measure
percent recovery by applying a compressive force to a panel
domain sufficient to compress the panel domain to 50 percent
of its non-compressed thickness. Relieve the compressive
force and measure the panel domain thickness after 24 hours.
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The panel domain thickness 24 hours after relieving the
compressive force divided by the uncompressed thickness of
the panel domain is the compressive recovery for the panel
domain. A conformable panel domain preferably has a
compressive recovery of 60 percent or more, more preferably
70 percent or more, still more preferably 80 percent or more.
Preferably, compressing at least one conformable panel
domain in a building panel reduces at least one dimension of
the building panel. Reducing a dimension of a building panel
can allow insertion of the building panel into, for example,
a cavity having a width less than the uncompressed dimension
of the building panel.
More preferably, the building panel has a compressive
recovery when no longer compressing the conformable panel
i5 domain(s). The compressive recovery of a building panel
desirably supplies sufficient pressure against cavity walls
to fractionally retain the building panel within a cavity.
Generally, the compressive recovery will cause a building
panel to apply a pressure of 100 Newtons-per-square-meter
(N/m2) or more, preferably 200 N/m2 or more, more preferably
300 N/m2 or more. A pressure of less than 100 N/m2 is
generally insufficient to fractionally retain a building
panel within a cavity without buckling or sagging. Usually,
the pressure is 200,000 N/m2 or less, preferably 50,000 N/m2
or less, more preferably 30,000 N/m2 or less. Building panels
that apply a pressure greater than 200,000 N/m2 are typically
very difficult to compress.
Suitable conformable panel domains include polymeric
foam and fibrous materials such as fiber batting, glasswool,
3o carbonaceous fiber, and mineral wool. Preferably, the
conformable panel domain is a polymeric foam, more preferably
an open-celled polymeric foam. Foams for use in conformable
panel domains desirably have an open cell content of 5
percent or more, more desirably 10 percent or more, still
more desirably 30 percent or more, and most desirably 50
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percent or more, according to ASTM method D2856-A. A
polymeric foam having less than 5 percent open cell content
often lacks a desirable compressibility.
Adjacent panel domains within a building panel may have
distinct, gradient, or variable boundaries. Two adjacent
panel domains have a distinct boundary when at least one
building panel property, such as compressive strength or
density, abruptly changes from that of one panel domain to
that of another panel domain. An abrupt change is one
Zo occurring in a distance of 0.5 cm or less, preferably 0.2 cm
or less, more preferably 0.1 cm or less. For example, gluing
two pieces of polymeric foam having different compressive
strengths together along adjacent edges can create-a building
panel having two panel domains and a distinct boundary
i5 between those panel domains. Distinct boundaries separating
panel domains by greater than 0.5 cm tend to become gradient
boundaries or variable boundaries, or even another panel
domain.
Alternatively, two panel domains may have a gradient
2o boundary where at least one property is either in between
that of each individual panel domain or gradually changes
from that of one panel domain to that of an adjacent panel
domain. For example,~extruding two foams having different
densities such that they blend together at an interface can
25 produce a building panel having a gradient boundary that
gradually changes from the density of one panel domain to
that of the adjacent panel domain. The interface between two
panel domains connected with a lap joint would also
constitute a gradient boundary.
3o Two panel domains may instead have a variable boundary
where at least one building panel property is variable but
not steadily changing across the boundary from that of one
panel domain to that of the other.
One variation of the present invention is a square or
35 rectangular building panel having bands. Bands preferably
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traverse the largest dimension of a primary face (the
building panel length) and that of its opposing face. Bands
may extend orthogonally from one end of the building panel to
an opposing end, traverse the building panel diagonally such
as from one corner to an opposing corner, or may extend from
one end to another in a non-linear shape. Bands can be any
shape and size, though they preferably are thicker than they
are wide to prevent buckling during compression.
One desirable building panel configuration contains a
i0 conformable band along at least one edge of a square or
rectangular building panel. Such a band is a "conformable
edge band". Conformable edge bands allow the building panel
to conform to obstacles, such as conduit and plumbing pipes,
along cavity walls. Another beneficial building panel
i5 configuration comprises conformable panel domains along the
ends of the building panel that can fit to obstacles that
extend across the end of the building panel within a cavity.
A building panel, be it square, rectangular or some other
shape, may have a perimeter comprising one or more
2o conformable panel domains.
Another variation of the square or rectangular building
panel comprises at least one conformable band within the
building panel that allows the building panel to bend into a
non-planar configuration, facilitating insertion into a
25 cavity.
One desirable panel domain configuration for the
building panels of the present invention has alternating
conformable and rigid panel domains, or alternating rigid and
conformable bands. A rigid panel domain is a panel domain
3o having a higher average compressive strength than any
adjoining conformable panel domain. For example, a square or
rectangular building panel may have alternating rigid and
conformable bands. FIGS 1, 2a, 2b, and 2c show examples of
building panels having alternating conformable and rigid
35 panel domains.
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FIG 1 shows an example of a building panel 10 having a
panel thickness T and comprising two panel domains, 20 and
30. Panel domains 20 and 30 are bands within building panel
10. Panel domain 20 has a higher average compressive strength
than panel domain 30. A primary face 15 of building panel 10
comprises faces 22 and 32, respectively, of panel domains 20
and 30. FIG 1 shows an interface 40 between panel domains 20
and 30 as a variable boundary. FIG 1 shows an edge 12 of
building panel 10, which also serves as an edge of panel
domain 30. Building panel 10 has a length L equaling that of
panel domain 30. Building panel 10 has width W.
FIGs 2a, 2b and 2c show an example of a building panel
50 having five panel domains 60, 70, 80, 90, and 100. All
five panel domains are bands of building panel 50. Panel
domains 60, 80, and 100 are conformable. Panel domain 80
allows building panel 50 to bend into a non-planar
configuration. FIG 2a shows building panel 50 and cavity
115. The width W' of building panel 50 is larger than the
spacing between cavity walls 110 and 120, which define cavity
115. FIG 2b shows building panel 50 after bending into a non-
planar configuration for insertion into cavity 115. Applying
force F against panel domain 80 returns building panel 50
into a planar configuration within cavity 115, compressing
panel domains 60, 80, and 100. FIG 2c shows building panel
50 within cavity 115.
Building panels of the present invention may include at
least one slit traversing a primary face or a face opposing a
primary face and extending to a depth less than the panel
thickness. Such slits facilitate bending a building panel
into a non-planar configuration for insertion into a cavity.
FIGS 2a, 2b, and 2c also show such an optional slit 82 in
panel domain 80. FIG 2b shows slit 82 open slightly when
building panel 50 bends into a non-planar configuration,
thereby facilitating the bending of building panel 50.
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FIG 3a shows a building panel 130 with two panel domains
132 and 134. Panel domain 134 is a conformable panel domain
disposed around the perimeter of building panel 130. FIG 3a
shows panel domain 134 as a single piece, but it may also
consist of multiple pieces. FIG 3b shows a similar building
panel 140 having panel domain 142 and multiple conformable
panel domains 144, 146, 148, and 150 around the perimeter of
building panel 140.
Building panels may have a tongue or a groove profile on
1o at least one minor face. A tongue profile contains a tongue
and, preferably, one or two shoulders. Similarly, a groove
profile contains a groove and, preferably, one or two
shoulders. A tongue on one building panel advantageously
fits into a groove on an adjacent building panel to form a
i5 joint between building panels. Any tongue and groove shape
is feasible, but rounded shapes are beneficial, enabling the
tongue of one building panel to roll into the groove of
another building panel. Shoulders assist in keeping the
tongue of one building panel from moving out of the groove of
2o an adjacent building panel, thereby causing buckling or
sagging at the joint between the two building panels.
Shoulders, if present, consist of greater than zero percent,
preferably 5 percent or more, more preferably 10 percent or
more of the panel thickness and desirably 95 percent or less,
25 preferably 80 percent or less and more preferably 60 percent
or less of the panel thickness. If the shoulders consist of
greater than 95 percent of the panel thickness the tongue
tends to easily break.
FIGS 4a and 4b show an end-on view of two building
3o panels 160 and 170, and cavity 185, defined by cavity walls
180 and 190. Building panel 160 comprises a conformable
panel domain 162 and a rigid panel domain 163 with a tongue
profile comprising a tongue 164 and shoulders 166 and 168.
Building panel 170 comprises a conformable panel domain 172
35 and a rigid panel domain 173 with a groove profile comprising
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a groove 174 and shoulders 176 and 178. Building panels 160
and 170 connectively insert into cavity 185 by placing
conformable panel domains 162 and 172 against cavity walls
180 and 190, respectively, and sliding tongue 164 into groove
174 while applying force F' against rigid panel domains 163
and 173. FIG 4b shows building panels 160 and 170
connectively inserted into cavity 185 with conformable panel
domains 162 and 172 compressed slightly.
Generally, when two or more building panels adjoin one
1o another within a cavity, pressure resulting from a compressed
panel domain's resiliency is sufficient to hold adjoining
building panel together. However, adjoining edges of two
adjoining building panels can have an adhesive between them
to prevent the building panels from separating. Similarly,
i5 applying adhesive tape or any type of fastener along primary
faces of adjoining building panels and across adjoining edges
can help to prevent the building panels from separating.
One suitable method for preparing building panels of the
present invention is by joining together discrete panel
2o domains, such as different pieces of polymeric foam or
combinations of polymeric foam and fibrous materials, to form
a single building panel. A skilled artisan can identify any
of a number of means suitable for joining together two panel
domains including double sided tape, epoxy or polyurethane
25 adhesives, latex adhesives, hinges, and wires inserted into
and possibly through adjoining panel domains. Melt welding
polymeric panel domains together using heat or solvents is
also acceptable.
Another suitable method for preparing building panels of
3o the present invention is by chemically, mechanically, or both
chemically and mechanically modifying at least one domain
within a building panel initially having an essentially
homogeneous compressive strength. For example, buckling or
fracturing cell walls or perforating, slicing, or removing
35 portions of a polymeric foam panel domain tends to lower the
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compressive strength of that panel domain. Slices within a
panel domain may be either in a plane or perpendicular to a
plane of compression and still lower a compressive strength
of the panel domain. Slices in the plane of compression may
result in localized buckling of the panel domain. Chemically
modifying a panel domain of a polymeric foam also can create
panel domains of differing compressive strength. For
example, adding a plasticizer to a polymeric foam tends to
lower its compressive strength while adding a crosslinker
to tends to increase the compressive strength of the foam.
Chemical and mechanical modifications are also useful for
creating domains of differing compressive strengths in
building panels that do not have an initially essentially
homogeneous compressive strength.
Still another acceptable method for preparing a building
panel of the present invention is by simultaneously
manufacturing the panel domains in such a manner that
adjacent panel domains join during manufacturing. For
example, coextruding different polymeric foams through dies
2o adjacent to each other such that, during expansion, the
polymer foams contact each other and coalesce at a joint
where contact occurs. The different foams then form
different panel domains in a polymeric foam building panel.
Similarly, coalesced strand foam technology is
acceptable for preparing building panels of the present
invention. In fact, coalesced strand foam technology has
unique advantages over other foam technologies in preparing
the building panels.
Coalesced strand foam technology involves extruding a
foamable gel through a die comprising multiple holes to foam
a strand foam. The "strands" extrude through the holes,
expand, and bind to one another creating a structure, such as
a building panel, comprising multiple foam strands. A foam
structure comprising a number of coalesced foam strands is a
strand foam. Each strand has a skin and a core. The skin
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wraps around the core and has a higher density than the core.
Stands typically bind together as their skins coalesce during
expansion. The use of an adhesive to bind strands together
or help assist in binding strands together is also
acceptable.
The compressive strength of a strand foam is a function
of many parameters. Herein, compressive strength corresponds
to compressive strength during radial strand compression when
in reference to a strand foam. For example, a strand foam
to having a given number of strands per cross-sectional area
typically has a higher compressive strength than a strand
foam having fewer strands per cross-sectional area. One
possible reason for a higher compressive strength in the
strand foam having more strands per cross-sectional area is
that more strands correspond to more skin in a strand foam
cross section. The skin establishes a support structure
through the strand foam cross section that resists
compression.
Interstrand spaces also lower a strand foam's
2o compressive strength. Interstrand spaces form when strands
are sufficiently small or spaced sufficiently far apart so
that neighboring strands touch one another only periodically
while expanding. The places where the strands do not touch
remain as voids between strands. These voids are interstrand
spaces. Interstrand spaces reduce the compressive strength
of a strand foam by allowing strands to compress into the
spaces instead of into a neighboring strand.
An artisan of ordinary skill in the art can identify,
without undue experimentation, many ways to prepare strand
3o foams having different compressive strengths.
Modifying a die through which the foam strands extrude
can modify many strand foam parameters, including the
compressive strength of a strand foam. A die typically has a
certain number of holes per unit area. The holes have a
certain shape, size, and a certain orientation in the die.
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For a given foamable gel extruded through the die to form a
strand foam, the number of holes per unit area in the die
dictates the number of strands per unit cross-sectional area
in the resulting strand foam. The hole shape dictates the
shape of the foam strands. The hole size dictates the strand
size. The hole orientation dictates the interstrand
orientation in the strand foam.
Extruding a foamable gel through a die having two or
more sections differing in at least one of the following:
1o number of holes per unit area, hole shapes, and hole spacings
can create a strand foam having different panel domains. For
example, one section of a die may have a specific number of
holes per unit area and an adjacent section of the die may
have fewer holes per unit area. Expanding a foamable gel
through such a die will create a strand foam building panel
having one panel domain of a specific number of strands per
cross-sectional area adjoined to another panel domain having
fewer strands per cross-sectional area. The panel domain
having fewer strands per cross-sectional area will have a
lower compressive strength than the panel domain having more
strands per cross-sectional area.
Foam strands may be solid or hollow. Solid strands have
foam through the full cross-section of the strand. Hollow
strands have foam only around a circumference of the strand
cross-section such that the center of the strand cross-
section does not contain foam. Hollow strands, and their
preparation, are further described in United States patent
application number 09/706,110 ('110) (see, page 2 line 30
through page 5 line 17). Hollow strands tend to have a lower
3o compressive strength when compressed radially than solid
strands. Building panels of the present invention may
contain hollow strands or solid strands, but are essentially
free of a combination of hollow and solid strands. A
building panel is essentially free of a combination of hollow
and solid strands if the difference between the number of
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solid foam strands and the number of hollow foam strands is
greater than 90 percent, preferably greater than 95 percent,
more preferably greater than 98 percent of the total number
of strands.
Polymeric strand foam typically comprises at least one
organic polymer for preparing polymeric strand foam. Organic
polymers include alkylene aromatic polymers, polyolefins,
rubber-modified alkylene aromatic polymers, alkylene aromatic
copolymers, hydrogenated alkylene aromatic polymers and
1o copolymers, alpha-olefin homopolymers and copolymers, or
blends of the foregoing polymers with a rubber. Preferred
polymers include homopolymers and copolymers of PP, PE, and
PS, including ESI.
Building panels of the present invention may work in
i5 conjunction with building panels outside of the scope of the
present invention in order to span a cavity. For example,
FIGS 5a and 5b show building panels 220 and 230 working in
conjunction to span cavity 205. Building panel 220 contains
panel domains 222 and 224. Panel domain 222 is conformable.
20 Building panel 230 contains single panel domain 232 having
opposing edges 234 and 236. FIG 5a shows building panels 220
and 230 inserting into cavity 205, with panel domain 222
against cavity wall 200 and edge 234 of panel domain 232
against cavity wall 210. Position edge 226 of building panel
25 220 against edge 236 of building panel 230 and apply force F"
against edges 226 and 236 to position building panels 220 and
230 into cavity 205. Panel domain 222 compresses as the
building panels insert into cavity 205. FIG 5b shows
building panels 220 and 230 within cavity 205.
3o A building panel of the present invention may connect to
at least one other building panel, which may or may not be
within the scope of this invention, using at least one hinge
to create a hinged building panel. A hinged building panel
is capable of reversibly bending at the hinges) to assume a
35 non-planar configuration for insertion into a cavity.
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Similarly, at least one panel domain may connect at least one
other panel domain via at least one hinge. Suitable hinges
include bendable polymer or metal strips, polymer or metal
films, or actual devices designed for hingedly connecting
structures. Hinges may attach to the primary faces of
adjacent building panels or panel domains, attach to minor
faces of adjacent building panels or panel domains, or
penetrate into adjoining building panels or panel domains.
One building panel variation includes a hinge between one or
to two conformable panel domains where, upon insertion of the
building panel into a cavity, the'conformable panel domains)
compresses and conforms around the hinge to tightly contact
the panel domain to which it is hingedly connected.
Panel domains, even entire building panels, can include
facers on at least one surface, particularly a primary
surface. Suitable facers include polymeric films, metal
sheets and foils (such as aluminum foil), paper, woven and
non-woven materials including glass fiber and cloth, and
combinations thereof. Such facers can provide additional air
barrier properties to a building panel, can act as a hinge
between panel domains, can enhance the decorative nature of
the building panel and assist in keeping the building panel
from buckling or sagging. Facers can, but need not, cover an
entire surface of a building panel.
Many building panel configurations are conceivable
within the scope of the present invention. For example, a
foam building panel comprising a single foam can have
cylindrical plugs of another foam (or some other panel domain
material), that has either a higher or lower compressive
3o strength than the foam building panel, disposed through the
foam thickness in a specific pattern to direct compression of
a foam under pressure. Alternatively, building panels
comprising a principal domain material can have tapered or
grooved sections that are filled with a domain material other
than the principal panel domain material. An artisan can
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conceive of many different configurations that fall within
the scope of the present invention.
Building panels of the present invention are useful as
thermal insulation, acoustical attenuators and insulators,
decorations, or simply to fill a cavity to, for example, keep
insects or rodents from entering the cavity. The building
panels are particularly useful for placing within wall and
roof cavities in houses, garages and other buildings. The
building panels of the present invention are also useful for
Zo placing within wall cavities of, for example, portable
insulating containers.
The following examples further describe the invention
and do not limit the scope in any way. Determine compressive
strength (stress) values using European Norm (EN) 826, or as
25 otherwise indicated. Determine thermal conductivity
according to EN 28301 at 10°C.
Examples (Ex) 1 and 2. Comparison of Building Panels with
and without Conformable Edge Bands
Ex 1 illustrates a building panel of the present
2o invention originating from a single strand foam panel. Ex 1
contains a conformable panel domain that is not along a panel
edge.
Ex 2 illustrates a building panel of the present
invention similar to Ex 1 that further comprises conformable
25 panel domain on opposing panel edges ("conformable edge
bands"). Ex 2 is similar to the panel in FIG 2a and 2b. Ex
2 can conform to larger diameter obstacles on the wall of a
cavity than a similar panel free of conformable edge bands,
such as Ex 1.
3o Prepare Ex 1 and Ex 2 using panels of polyolefin-based
coalesced strand foam (such as PROPELT"~ 12-20 polymeric foam,
PROPEL is a trademark of The Dow Chemical Company) 130 cm
long, 60 cm wide, and 10 cm thick. Create a conformable
panel domain in Ex 1 and Ex 2 by perforating through the foam
35 in a 10 cm wide band through the center of the building
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panel. Perforate by needle punching using 2 mm diameter.
needles positioned 5 mm apart along orthogonal axes. Create
conformable edge bands on Ex 2 by perforating a panel domain
cm wide along the edges of Ex 2, using the same needle
5 punching procedure as when forming the 10 cm wide conformable
band. The non-perforated panel domains in Ex 1 and Ex 2 are
rigid panel domains. Both Ex 1 and 2 illustrate building
panels having panel domains that are bands.
Table 1 shows the compressive strength for the rigid and
1o conformable panel domains of Ex 1 and 2. Percent strain
corresponds to percent compression.
Table 1. Compressive Strength in kPa For the Panel Domains in
Ex 1 and 2.
Panel Domain 10% 25 0 50 0 70% 90 0
Strain strain strain strain strain
Rigid 23.3 29.0 72.8 123 294
Conformable 12.5 20.8 33.6 54.8 191
Further modify the 10 cm wide conformable panel domain by
slicing a 90-95 mm deep slit along the length of the panel
domain, generally in the center of the width dimension, using
a hot blade.
2o Create a testing cavity by placing two studs parallel to
each other and a specified distance apart, with a major
planar surface of one stud facing a major planar surface of
the other stud. The volume between the two studs defines the
cavity with the stud spacing defining the cavity width. The
surface of each stud has a width (defining the depth of the
cavity) of greater than 10 cm. Tilt the studs so that the
cavity is at a 45 degree angle, relative to horizontal, to
simulate a roof pitch.
Place a cylindrical object of a specified diameter along
3o the major planar surfaces of a stud. The object simulates,
for example, a cable, conduit, or pipe along a stud or joist.
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Place either Ex 1 or Ex 2 into the cavity by first
bending the building panel along the slit in the 10 cm wide
conformable band, inserting the panel edges into the cavity
and against the stud surfaces, and then pressing along the
slit until the building panel is fully inside the cavity
(see, for example, FIGs 2a and 2b). Both Ex 1 and 2 tightly
fit into the cavity without buckling when the stud spacing is
between 60 cm and 56 cm. Buckling occurs in the building
panel when the spacing is less than 56 cm, with buckling most
Zo evident in the 10 cm wide conformable band.
Ex 1 conforms to a cylindrical object having a diameter
of 5 mm or less, forming a tight seal with the stud. Ex 1
does not form a tight seal around a cylindrical object having
a 10 mm diameter or greater.
Ex 2 conforms to a cylindrical object having a 15 mm
diameter, forming a tight seal with the stud.
Ex 3: Building Panel Containing a Polyurethane Foam
Conformable Panel Domain
Ex 3 illustrates a building panel of the present
invention that contains a polyurethane foam conformable panel
domain. Ex 3 further illustrates an advantage of having a
conformable edge band for conforming around objects on a
cavity wall. Ex 3 has a structure similar to that of the
building panel in FIGS 2a and 2b. The panel domains in Ex 3
are examples of bands.
Cut two rigid domains 130 cm long, 20 cm wide and 10 cm
thick from a PS foam board, such as STYROFOAM~ Roofmate SL
polymeric foam insulation (STYROFOAM is a trademark of The
Dow Chemical Company). Cut three conformable bands 130 cm
long and 10 cm thick, two of them 5 cm wide and one of them
10 cm wide from a flexible polyurethane (PU) foam (such as PU
foam 16F from Metzeler Mousse). Adhere the panel domains
together using a two-part epoxy adhesive along the 130 cm
long and 10 cm thick edges to create a building panel having
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similar dimensions to Ex 2 and having the following panel
domain orientation:
cm PU foam/PS foam/10 cm PU foam/PS foam/5 cm PU foam
Table 3 shows the compressive strength profile for the
5 PU foam. For comparison, the compressive strength for the PS
foam is 229 kPa at yield.
Table 3. Compressive Strength of Flexible Polyurethane Foam
(in kPa)
10% strain 25% strain 50o strain 70o strain 90% strain
5.07 5.47 5.77 8.72 61.96
1o Insert Ex 3 into the testing cavity using the procedure
described in Ex 1 and 2. Ex 3 fits into cavities having a
spacing from 60 cm to 56 cm without buckling and tightly
conforms around a cylindrical object having a 15 mm diameter
on a major planar surface of the cavity wall.
Ex 4. Polyurethane Building Panel
Make a building panel as described for Ex 3 except use a
rigid polyurethane foam instead of a PS foam. The rigid
polyurethane foam has a density of 35 kg/m3, according to
EN1602, a compressive strength of 146 kPa at yield, and a
2o thermal conductivity of 19 milliwatts per meter-Kelvin
(mW/m*K) .
Ex 4 performs similarly to Ex 3 and further illustrates
a building panel of the present invention comprised of
polyurethane foam. The thermal conductivity of the hard
polyurethane foam makes this a particularly attractive
thermally insulating building panel.
Ex 5. Rock Wool Buildinct Panel
Ex 5 illustrates an all-fiber building panel of the
present invention.
3o Cut a piece of rock wool having a density of 55 kg/m3
(such as ROCKPLUST"" insulation, ROCKPLUS is a trademark of
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Rockwool) into a panel 130 cm long, 60 cm wide, and 10 cm
thick. Compress a 10 cm wide conformable band the full 130
cm length through the center of the panel to 20 percent of
its original thickness using either a roller or a hydraulic
press. Compressing the panel elastifies the rock wool
structure, creating a conformable domain. The panel assumes a
rigid band/conformable band/rigid band configuration. This
panel is Ex 5.
Table 4 shows the compressive strengths of the non-
lo compressed (rigid) bands and the compressed (conformable)
band.
Table 4. Compressive strength in kPa for compressed and non-
compressed bands in Ex 5.
Panel Domain 5% Strain 10% strain 25% strain 50o strain
Non-Compressed 2.5 5.2 9.9 18
(rigid)
Compressed 1.1 1.4 2.9 16
(conformable)
Ex 5 securely fits with a cavity spacing of 57 cm using
the cavity wall test apparatus from Ex 1.
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