Note: Descriptions are shown in the official language in which they were submitted.
CA 02553186 2013-01-09
Atty. Doc. No. 167-03
PROCESS OF AND APPARATUS FOR MAKING A SHINGLE, AND SHINGLE
MADE THEREBY
Background of the Invention:
In the art of making roofing shingles and tiles for exterior application in
the
building industry, various approaches have been made toward making shingles
and tiles
that are manufactured, but give the appearance of being made of traditional
natural
materials, such as wood cedar shakes, tiles, slate, etc.
In many instances, such shingles and tiles are made of bitumen coated mat
having
granules on the exterior surface, with the granules being provided in various
designs,
shades, color configurations, etc., to yield various aesthetic effects.
It is also known, in making roofing shingles and tiles, to mold them to the
desired
shape by various molding techniques. The materials that are used in such
molding
techniques usually include inexpensive filler material, in order to achieve
low production
costs.
Some such filler materials can be various waste products, such as carbon
black,
recycled rubber and tire crumb, coal fines, pulp and paper waste and other
inexpensive
materials.
Such products are often made by molding multi-component formulations, which
comprise blends of virgin and recycled polymers and various low-cost fillers.
The use of large quantities of such fillers reduces the mechanical properties
of the
ultimate product, however. Additionally, the use of large quantities of
fillers limits the
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color variations that are possible in the products and makes the processing of
the
formulations into shingles and tiles very difficult.
Typically, roofing shingles and tiles made of such material having waste for
filler
do not provide good weather resistance for the products. Additionally, the
warranty
periods that can reasonably be provided for such products tend to be short in
duration.
Furthermore, such building industry roofing products have relatively low
impact
strength, especially at low temperatures. Insofar as their available colors
are concerned,
such tend to be limited to the colors gray and black.
Additionally, molding operations tend to be capital intensive, with relatively
high
manufacturing costs, although molding techniques do provide a high level of
definition or
dimension control. Also, there is a disadvantage to molding techniques, in
general, in
that the length of the cycle for injecting material into the mold, molding to
the desired
shape, and ejecting the shape from the mold is largely a function of the time
required to
cool the molten thermoplastic material before it can be removed from the mold.
However, the temperature of the thermoplastic material must be sufficiently
high that it
can flow and fill the cavity within the constraints of the material and
equipment (i.e.
material characteristics, melt pressures, mold clamping pressures, etc.).
While
modifications can be made to the materials to help the flow characteristics
and thereby
lower the required melt temperature, and while improvements can be made to the
mold to
increase heat transfer and removal, cooling remains the longest part of the
cycle for these
processes. In order to achieve the necessary cooling, the time required causes
a
lengthening of the manufacturing cycle, which increases the capital costs of
investment in
molds and machinery for a required output, thereby substantially increasing
manufacturing costs.
Summary of Invention:
The present invention is directed to a process of making a shingle having a
desired configuration, by a combination of extruding and molding, in order to
reduce the
time required for the molding operation. As used throughout the application,
"shingle"
should be considered to embrace "tile" also.
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It is a further object of this invention to accomplish the above object by co-
extruding the shingle to include a core material with a shingle capstock
material on a
major surface.
It is a further object of this invention to accomplish the above objects, in
which
the extruding step is a continuous process, and in which the extrudate is
serially cut into
discrete preliminary shingle shapes, prior to molding those shapes into the
final shingle
shape.
Additional objects of this invention include producing shingles by the
processes
described above.
Further objects of this invention include providing apparatus for
accomplishing
the processes for producing shingles as described above.
Other objects and advantages of the present invention will be readily apparent
upon a reading of the following brief descriptions of the drawing figures,
detailed
descriptions of the preferred embodiments, and the appended claims.
Brief Descriptions of the Drawing Figures:
Fig. 1 is a vertical, sectional view of a process and apparatus for extruding
a
preliminary shingle shape and serially severing the extrudate into a plurality
of
preliminary shingle shapes, for delivery to a molding station, with the
delivery means
being fragmentally illustrated at the right end thereof.
Fig. 2 is a top plan view of that which is illustrated in Fig. 1.
Fig. 3 is an illustration similar to that of Fig. 1, but wherein the extruding
operation includes both core material and skin or capstock material, being co-
extruded
prior to the serial severing step, with the delivery means also being
fragmentally
illustrated at the right end thereof.
Fig. 4 is a top plan view of one embodiment which is illustrated in Fig. 3,
wherein
the skin or capstock material covers a portion of the top surface of the
extrudate.
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Fig. 5 is a schematic vertical elevational view of a compression molding
station
adapted to receive preliminary shingle shapes delivered from the right-most
end of the
illustrations either of Figs. 1 and 3, for compression molding the shapes into
their final
configuration.
Fig. 6 is a top view of the compression molding station of Fig. 5, taken
generally
along the line VI-VI of Fig. 5, and with an indexable mold handling table
illustrated at
the right end thereof, with a robot and robot arm being schematically
illustrated for
removal of shingles from molds carried by the indexable table.
Fig. 7 is a schematic elevational view of upper and lower mold components
shown in the open position, at one of the stations on the indexable table,
with the
indexable table fragmentally illustrated, and with a robot arm for lifting the
finished
shingle from the mold.
Fig. 8 is an enlarged generally plan view of an upper mold component, taken
generally along the line of VIII-VIII of Fig. 5.
Fig. 9 is an enlarged generally plan view of a lower mold component, taken
generally along the line of IX-IX of Fig. 5.
Fig. 10 is an enlarged vertical sectional view, taken through the upper and
lower
mold components, generally along the line X-X of Figs. 8 and 9.
Fig. 11 is a top perspective view of a finished shingle made in accordance
with
this invention.
Fig. 12 is a vertical sectional view, taken through a shingle made in
accordance
with this invention, generally along the line XII-XII of Fig. 11, wherein the
shingle is
comprised of two single layers of material, one being a core layer and the
other being a
partial capstock or skin layer.
Fig. 12a is an illustration like that of Fig. 12, but wherein the shingle is
comprised
of three layers of material.
Detailed Descriptions of the Preferred Embodiments:
Referring now to the drawings in detail, it will be seen that, in accordance
with
this invention, the shingle or tile will first be pre-shaped by extruding a
cross-section that
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=
will be generally similar to the finished cross-section of the shingle or
tile, with the pre-
shaped or preliminary shingle shape then being allowed to cool somewhat prior
to
placement of it in the mold. By first getting the preliminary shingle shape to
conform
closely to the final shingle shape before placing it in the mold, long flow
distances and
hence higher material temperatures are avoided. The material in the mold is
then
compression molded to achieve its final dimensions. Because significant
amounts of heat
are removed prior to placement of the preliminary shingle shape into the mold,
very short
cooling cycles are achieved.
In another embodiment, the amount of cooling is minimized prior to placement
in
the mold. In this way, significant amounts of heat do not need to be provided,
thus the
shortened cooling cycle is obtainable. Also, higher molecular weight polymeric
materials
with higher viscosities and better polymer performance properties, which would
not
normally be useful in a molding operation such as injection molding, can be
used,
because the shape of the precursor is close to that of the molded piece and
the amount of
material flow necessary to produce the desired finished shingle shape is
minimal.
Referring now to Fig. 1, it will be seen that an extruder is generally
designated by
the numeral 20 for receiving generally thermoplastic pellets 21 into an inlet
hopper 22
thereof, and with an auger 23 being rotatably driven, to urge the pellets
through the
extruder 20 in the downward direction of the arrow 24, through the extruder,
to be
discharged at discharge end 25. It is desirable to dry the pellets prior to
adding them to
the extruder in some instances, depending on the composition of the pellets.
Such drying
may include exposing the pellets to a drying cycle of up to 4 hours, at an
elevated
temperature, such as, for example, 180 F. Suitable means, such as electric
coils 26 are
provided for heating the thermoplastic material 21 in the extruder, so that
the same can be
extruded into a desired shape as may be determined by the outlet mouth 25 of
the
extruder 20. The extrudate 27 is then moved horizontally in the direction of
the arrow 28,
beneath a transverse cutting mechanism 30 in the form of a guillotine, which
is movable
upwardly and downwardly in the direction of the double-headed arrow 31, with
the blade
32 of the guillotine, operating against an anvil 29, to sever the extrudate 27
into a
plurality of preliminary shingle shapes 33. The shapes 33 then pass onto an
upper run 34
of a continuously moving conveyor belt 35 driven between idler end roller 36
and motor-
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driven end roller 37, with the upper run 34 of die belt 35 being supported by
suitable idler
rollers 38, as the preliminary shingle shapes 33 are delivered rightward, in
the direction
of the arrow 40 illustrated in Fig. 1. In lieu of a guillotine 30, any other
type of cutting
mechanism, such as for example only, a blade or other cutter movable
transversely across
the belt 34, or the die lip at the discharge end 25 of the extruder, in a
direction
perpendicular to the arrow 40 can be used to separate the extrudate into a
plurality of
shapes 33. The belt which supports the shapes can be a vented belt made of a
suitable
material, such as, for example, a silicone coated belt, or a metal mesh belt,
or the like, in
order to control bubbling or outgassing of gasses from the extrudate, if
desired.
It will be seen that in the embodiment of Figs. 1 and 2, the preliminary
shingle
shapes 33 are extruded into a single layer of material from the shingle
extruder 20.
With reference now to Figs. 3 and 4, it will be seen that the extrudate 45 is
cut
into a plurality of multiple layer preliminary shingle shapes 46, in that the
process as
shown in Figs. 3 and 4 is a co-extrusion process, whereby a capstock or skin
material 47
may be extruded through extruder 48, while a core material 50 is extruded
through
another extruder 51, each with their own thermoplastic heating systems 52, 53,
such that
the discharge mouth 54 of the co-extruder 55 produces multiple layer
preliminary shingle
shapes 46, as shown.
The other details of the apparatus as shown in Figs. 3 and 4, including the
guillotine, anvil, conveyor belt, rollers, etc. are all otherwise similar to
the comparable
items described above with respect to Figs. 1 and 2.
The conveyor will preferably have a take-off speed that is matched to the
extrusion speed, such that after extrusion of a given length, the cutting is
effected by the
guillotine or the like, and the speed of the conveyor can be controlled.
Alternatively, two
conveyors may be disposed serially, with the speed of the upper run of the
first conveyor
being accelerated to deliver the shapes to the second conveyor after cutting,
with the
speed of the first conveyor then being re-set to match the extrusion speed of
extrudate
leaving the extruder, with the second conveyor being controlled for delivery
of the shapes
to the mold. Alternatively, rather than having the delivery being automatic,
the same
could be done manually, if desired.
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Thus, with reference to Figs. 3 and 4, the multiple layer preliminary shingle
shapes 46 are delivered generally rightward, in the direction of the arrow 56.
It will be noted that the preliminary shingle shapes 46 that are co-extruded
as
shown in Figs. 3 and 4 are illustrated as comprising preliminary shingle
shapes
comprising a core material 57 that is substantially the full length of the
shapes as shown
in Fig. 4, with a capstock material 58 on an upper surface thereof, that is
slightly more
than half the dimension of the full length of the shingle shapes 46 shown,
terminating at
60 as shown. Alternatively, capstock material 58 could cover a lesser or
greater portion
of the upper surface, or even the entire upper surface of the shingle shape.
Referring now to Fig. 5, it will be seen that the shapes 46 or 33, as may be
desired, are delivered via the conveyor belt, in the direction of the arrow
61, to be placed
between mold components in a press, to be compression molded as will be
described
hereafter. In lieu of a conveyor belt, a moveable tray, a carrier, a platform
or other means
of supported transport could be used.
It will be noted that the extrusion and co-extrusion processes described above
are
continuous processes, and that the severing of the extrudate of whichever form
by the
guillotine is a serial, or substantially continuous process, and that the
delivering of the
preliminary shingle shapes from the extruder or co-extruder along the conveyor
belt
allows for the dissipation of heat resulting from the extrusion process, from
the
preliminary shingle shapes, in that, by allowing the shapes to substantially
cool prior to
placing them in the mold, rather than requiring the cooling to take place
completely in the
mold itself, reduces the required time for residence of the shapes in the mold
during the
compression process, as will be described hereinafter.
It will also be noted that maintaining the temperature above a melting
temperature
so that a quick flow of the melt can occur in the mold is desired in some
embodiments.
This maintaining of temperature above a crystallization or solidification
temperature can
minimize the development of internal stresses within the preliminary shingle
shapes that
could be caused by deformation of polymers that have begun to enter the solid
state.
As the preliminary shingle shapes approach the right-most end of the conveyor
belt as shown in Fig. 5, some suitable mechanism, such as the pusher rod 62,
shaft-
mounted at 63 and suitably motor-driven by motor 64, and operating in a back-
and-forth
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motion as shown by the double-headed arrow 65, pushes shapes 46 (or 33)
rightward, in
the direction of the arrow 66, along table 67, to the position shown, between
upper and
lower mold components 68, 70, respectively.
The mold generally designated 71 in Fig. 5 and comprised of upper and lower
mold components 68, 70, respectively, is movable into and out of its position
as shown at
the center of the ram mechanism 72, in the direction of the double-headed
arrow 73, from
an indexable table 74 that will be described hereinafter. The ram mechanism 72
operates
like a press, wherein a ram 75 is pneumatically, hydraulically or electrically
driven,
generally by means of a piston or the like within the upper end of the ram
mechanism, for
driving an electromagnet 76 carried at the lower end of the ram 75, for
lifting the upper
mold component 68 upwardly as shown.
The closing of the mold can be done, at a force of, for example, 40 tons, in
order
to cause a material flow out on the edges of the shingle being molded, for 3-4
seconds,
with the entire molding process as shown in Fig. 5 taking approximately one
minute, after
which the cooling of the molded material can take place, followed by removal
of the
molded material (shingle) from the mold, for subsequent or simultaneous
trimming of the
flashing therefrom. More preferably, a shorter molding cycle of 45 seconds can
also be
used.
The two mold components 68 and 70, when moved from the closed position on
table 74 shown at the right end of Fig. 5, to the open position shown at the
center of the
ram mechanism 72 of Fig. 5, separate such that the upper component 68 is
movable
upwardly and downwardly along guide rods 77, as the electromagnet 76 lifts a
preferably
ferromagnetic cap 78 carried by the upper mold component 68, such that, in the
open
position shown for the mold 71 in Fig. 5, a transfer mechanism 62 may move a
preliminary shingle shape 46 (or 33) along the table 67 in the direction of
the arrow 66, to
a position between the open mold components 68, 70 as shown.
The ram mechanism 72, itself, is comprised of a base member 80 and a
compression member 81, and the member 81 carries the ram 75. The compression
member 81 also moves vertically upwardly and downwardly, via its own set of
guide
rods 82, in the direction of the double-headed arrow 83, and is suitably
driven for such
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vertical movement by any appropriate means, such as hydraulically,
pneumatically,
electrically (not shown).
With reference now to Figs. 6 and 7, it will be seen that the mold 71 may be
moved to and from the ram mechanism 72, in the direction of the double-headed
arrow
73, by any appropriate means, such as by means of a hydraulic or pneumatic
push/pull
cylinder 89, driving a rod 84, that in turn has an electromagnetic push/pull
plate 85, for
engaging the ferromagnetic cap 78 of the upper mold component 68, as shown in
Figs. 5
and 7.
The indexable table 74 is rotatably driven by any suitable means (not shown),
to
move mold assemblies 71 into position for delivering them to and from the ram
station 72
as discussed above. In this regard, the indexable table 74 may be moved in the
direction of
the arrows 86.
If desired, in order to facilitate cooling, cooling coils may be embedded in,
or
otherwise carried by the table 74, such coils being shown in phantom in Fig.
7, at 87, fed
by a suitable source 88 of coolant, via coolant line 90, as shown. The coolant
can be
water, ethylene glycol, or any other useful coolant as may be desired.
Similarly, coolant coils are shown in phantom at 91 in Fig. 7 for the lower
mold
component 70 and may be provided with coolant from a suitable source 92, if
desired.
Also, optionally, the upper mold component 68 may be provided with internal
coolant
coils 93, shown in phantom in Fig. 7, likewise supplied by coolant from a
suitable source
94.
Upon the shapes 33 or 46 entering the mold, they may have a surface
temperature
of 300 F-320 F, with the temperature being hotter in the center of the core
material. Upon
leaving the mold, the surface temperature of the shapes will normally be in
the range of
80 F-85 F.
Within the mold, it is preferable to heat the top mold component 68 (which
will
preferably engage the capstock material) to a slightly greater temperature
than that of the
bottom component 70, in order to control internal stress development, i.e. to
provide a
controlling means for controlling internal stress development. For example,
the top
component 68 may be heated to 120 F, for example, with the bottom component
being
heated to 70-80 F. The subsequent cooling for the top plate 68 could be a
natural cooling
by simply allowing heat to dissipate, and the bottom plate can be cooled, for
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example, by well water, at about 67 F. Alternatively, well water or other
coolant could
be circulated, first through the bottom component 70 and then to the top
component 68,
however, in some instances it can be preferable to cool both components 68 and
70 to the
same temperature. It will also be understood that various other cooling
techniques can be
employed to regulate temperature at various locations in the mold, depending
upon the
thickness of the shingle being molded, in various locations of the shingle
being molded,
as may be desired.
At one of the stations shown for the indexable table 74, a lifting mechanism
95
may be provided, for opening the molds 71, one at a time. A typical such
lifting
mechanism may include a hydraulic or pneumatic cylinder 96, provided with
fluid via
fluid lines 97, 98, for driving a piston 100 therein, which carries a drive
shaft 101 that, in
turn, carries an electromagnet 102 for engaging the cap 78 of the upper mold
component
68, as the drive shaft 101 is moved upwardly or downwardly as shown by the
double-
headed arrow 103.
The closing of the components 68 and 70 relative to each other could
alternatively
be done under a force of 30 tons, rather the 40 tons mentioned above, in order
to obtain a
consistent closing and flow of material. Alternatively, the closing could
begin at a high
speed, and then gradually slow down, in order get an even flow at an edge of
the shape
that is being formed into a shingle.
When the mold 71 is in the open position shown in Fig. 7, and as is shown in
greater detail in Fig. 10, a plurality of spring pins 105, mounted in lower
mold component
70, in generally cylindrical cavities 106 thereof, are pushed upwardly by
means of
compressed springs 107, such that the upper ends of the spring pins engage the
compression molded shingle and pushed the same out of the lower mold cavity
108.
Similarly, spring pins 104 engage "flashing", or other material that has been
cut
away from the periphery of the formed shingle, for pushing the same out of the
trench
110 that surrounds the cavity 108 in the lower mold component 70.
As shown in Figs. 9 and 10, the lower mold 70, has, at the periphery of its
cavity
108, an upstanding cutting blade 109 separating the mold cavity 108 from the
peripheral
trench 110, for cutting the preliminary shingle shapes placed therein to the
precisely
desired dimensions of the final shingle, during the compression molding
process. That is,
CA 02553186 2014-01-02
generally, the preliminary shingle shapes may be slightly larger in size than
the final
shingle shape, to enable the cutting edge 109 to achieve the final desired
dimensions for
the shingle. The cutting of flashing from the shingle should be done quickly,
and it is
preferably done in the mold. The flashing can be recycled back for re-use,
most
preferably for use as part of subsequent core material. While the trimming of
the flashing
can be done in the mold, it could, alternatively, be done as a secondary
trimming and
finishing operation which, in some cases may be more cost effective than
trimming in the
mold.
Both the upper and lower mold cavities 111 and 108 are preferably provided
with
protrusions 112, 113, respectively, which protrusions will form reduced-
thickness nailing
or fastening areas in the compression molded shingle, as will be described
hereinafter.
With the fully formed shingle as shown in Fig. 7 having been lifted upwardly
out
of a lower mold component 70 by means of the spring pins, a computer control
robot
mechanism 119 or the like may control a robotic arm 114, having shingle-
engaging
fingers 115, 116, adapted to engage upper and lower surfaces of the
compression molded
shingle 117, and move the same horizontally out from between upper and lower
mold
components 68, 70, to another location for storage or delivery to another
station, as may
be desired.
Thereafter, the indexable table 74 may be moved, for delivery of a next
adjacent
mold to the station for engagement by the lift mechanism 95, with the table
74, generally
being rotatable on a floor 118, as allowed by a number of table-carrying
wheels 120.
Referring now to Figs. 8 and 9, specifically, it will be seen that the upper
mold
component 68 (Fig. 8) has a generally rectangular shaped upper mold cavity 1 1
1 that is
essentially the shape of a natural slate shingle 130 and has a headlap portion
125 and a
butt or tab portion 126. It will be noted that in the headlap portion there
are a plurality of
protrusions 112 that define reduced thickness areas in the compression molded
shingle
117, to serve as nailing or fastening areas, to make it easier for nails or
other fasteners to
penetrate the shingle 117 when it is nailed to a roof
There are also a plurality of mold recesses or protrusions 127 as may be
desired,
to build into the shingle 117 the appearance of a natural slate, tile or the
like. It will be
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understood that the number and style of the recesses/protrusions 127 will be
varied to
yield a natural-appearing shingle having the desired aesthetics.
In the tab or butt portion of the shingle 117, there is a gradually sloped
reduced-
thickness portion 140 (Fig 11) that is formed by a sloped reduced-thickness
portion 128
of the upper mold component 68 shown in Fig. 8 to be U-shaped, and which
defines the
periphery thereof. This sloped reduced-thickness portion 128, as shown in
Figs. 8 and 10,
acts as a flowing means and will serve to cause the capstock layer of the
preliminary
shingle shape being engaged, to flow peripherally outwardly around the edges
of the core
layer of material, such that, in the finished shingle, the exposed edges will
be covered by
capstock material, as well as the exposed surface, such that the edges of the
core layer of
shingle are weather-protected.
With reference to Fig. 9, it will be seen that the lower mold component 70 is
provided with a lower mold cavity 108, also having protrusions 113 therein,
for effecting
a reduced-thickness nailing or fastening area for applying a shingle to the
roof, in the
final shingle 117. It will be understood that, alternatively, the mold cavity
111 could be
the lower mold cavity and that the mold cavity 108 could be the upper mold
cavity, if
desired.
The spring pins 104, 105, and the trough 110 and mold depression 108,
respectively, as described previously, are also shown in Fig. 9.
It will thus be seen that the two mold components 68 and 70 are thus adapted
to
compression mold a shingle such as that which is shown by way of example only,
in Fig.
11.
The shingle of Fig. 11 thus has a headlap portion 131 and a butt or tab
portion 132,
with relief or other aesthetically pleasing areas 133, as shown, and with the
butt or tab
portion 132 having a capstock or skin 134 thereon, in the lower half of the
shingle,
terminating in upper capstock edge 135, such that, when shingles 130 are
installed on a
roof, a next-overlying tab or butt portion of a shingle will cover the upper
end, or headlap
portion 131 of the shingle 130. Alternatively, the capstock or skin 134 could
cover a
greater portion or even the entire top surface 137 of the shingle 130 (not
shown). For
example, the edge of the capstock coverage could optionally extend to be
coincident with
the upper edge 139 of the shingle 130.
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It will also be noted that there are nailing or other fastener reduced-
thickness
portions 136, in the shingle of Fig. 11, and that the U-shaped periphery along
the right
and left sides and lower edge of the shingle 130 slope downwardly from the top
surface
137 to the lower surface 138, as shown at 140.
With reference now to Fig. 12, it will be seen that the slope of the edges 140
is at
an angle "a", as shown in Fig. 12, which angle "a" will preferably be on the
order of
about 45 degrees (135 degrees between surfaces 137 and 140), and that such
slope may
be other than a straight line, such as having some aesthetic irregularity
built into the
shingle 130, as shown at the left end of Fig. 12.
It will thus be seen that the skin or capstock material 134 can substantially
encapsulate the tab or butt portion of the shingle of Figs. 11 and 12, that is
to be the
exposed portion of the shingle 130 when the shingle is installed on a roof,
leaving the
core material 141 to comprise a majority of the volume of the shingle 130.
In another embodiment, the skin or capstock material can substantially
encapsulate the entire top surface of the shingle 130, the core material
comprising a
majority of the volume of the shingle 130. In this embodiment portions of an
underlying
shingle between a pair of adjacent shingles in an overlying course are
protected with the
more durable skin or capstock material.
It will be understood that the core is preferably constructed of an
inexpensive
material, and that the capstock is preferably constructed of a material, such
as but not
limited to, a polymer having a high weather resistance and the ability to be
colored in
various colors, as well as desirable ultraviolet characteristics. In this case
where a
capstock also covers the upper portion or headlap area of the top surface of
the shingle
130, the capstock on the upper portion may be of the same or different color
or
appearance as that covering the lower portion 134.
It will also be understood that the shingle 130 may be constructed in various
other
configurations, to have edges that are segmented, scalloped or the like, or as
may be
desired. The relief areas 133 may comprise lines, grooves, or seemingly random
relief, as
may be desired, all to give the appearance of natural material such as slate,
tile, cedar
shake or the like. It will also be apparent that the shingles or tiles 130 may
be
constructed of various sizes as may be desired.
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With reference to Fig. 12a, it will be seen that a shingle 150 is provided,
also
having a core material 151 and a capstock material 152, like that of the
shingle 130 of
Fig. 12, but wherein a third layer 153 of another material is provided, that
essentially
sandwiches the core material 151 between the capstock material 152 and the
third layer
153 of material, in the tab or butt portion 154 of the shingle. The shingle of
Fig. 12a can
be constructed as described in the processes above, especially with respect to
the
processes described in Figs. 3 and 4, wherein there is a co-extrusion;
however, the co-
extrusion in the case of the embodiment of Fig. 12a would be in the form of
three
material layers rather than two layers, with the bottom layer 153 being
comprised either
of the same material as that of the capstock layer 152, or of a different,
third layer.
The core material will generally be of greater thickness than the skin
material
and will preferably be comprised of a highly filled polymer. The skin material
will
preferably be comprised of a polymer having high weather resistance and the
ability to be
colored in various colors as may be demanded by building designers.
The relative thickness of the capstock material to that of the core material
can be
about 10%, although, if additional capstock thickness is desired, one can
increase this
relative thickness up to about 20%. The minimum thickness of the capstock
material
should be on the order of about 4 mils, and the range for the same could be
from about 4
mils up to about 10 mils. In some instances, a 5% ratio of capstock material
to the total
thickness of the shingle can suffice, such that the capstock material would
comprise 5%
of the total thickness, with the core material comprising 95% of the total
thickness of the
shingle.
It will also be understood that variations can be made in the mold design, by
varying angles, radiuses and the like to avoid excessive thinning of the
capstock material,
all with a view toward controlling the capstock coverage of the core material,
not only on
the major surfaces, but also at the edges. Mold design can also be used to
provide
recesses or indentations in the lower surface of the shingle, thus allowing
lesser amounts
of material to be used.
By combining a skin material with a core material, such allows an economic
advantage in that a greater amount of filler may be used to comprise the core,
which will
be of less expense than the material that comprises the skin, without
providing
14
CA 02553186 2006-07-18
undesirable surface properties for the skin, and without limiting the
aesthetics of the
product, because the core is, at least partially, encapsulated in an
aesthetically pleasing
and weatherable skin. Additionally, the core can be comprised of a foam or
microcellular
foam material where reduced weight for the product is desired.
In some embodiments the shingle or tile is comprised of a core that is made of
a
low molecular weight material such as polypropylene filled with 40-80% by
weight of
recycled ash with suitable functional additives, encapsulated in a skin
comprised of a
film.
Such fillers for the core material can vary considerably and can be chosen
from a
group that includes, as examples, treated and untreated ashes from
incinerators of power
stations, mineral fillers and their waste, pulp and paper waste materials, oil
shale,
reclaimed acrylic automotive paint and its waste and/or mixtures of any of
these, or the
like.
The skin can be chemically cross-linked to increase its mechanical properties
and
weather resistance and/or flame resistance and can contain functional
additives such as
pigments, UV light stabilizers and absorbers, photosensitizers,
photoinitiators etc. The
cross-linking may occur during or after processing of the material. Such cross-
linking
can be effected by means which include, but are not limited to, thermal
treatment or
exposure to actinic radiation, e.g. ultraviolet radiation, electron beam
radiation, gamma
radiation, etc.
By way of example, the skin material is selected from a group of thermoplastic
materials comprising Polyolefins such as thermoplastic olefins, Polyethylene
(PE),
Polypropylene (PP), Polymethylpentene (PMP), Ethylene Acrylic Acid (EAA),
Ethylene
Methacrylic Acid (EMAA), Acrylonitrile Styrene Acrylate (ASA), Acrylonitrile
Ethylene
Styrene (AES) and Polybutene (PB-1), their copolymers, blends, and filled
formulations,
other polymers having high weather resistance such as Polyacrylates and
fluoropolymers
and/or their copolymers blends and filled formulations. The skin material is
preferably
stabilized for UV-light and weathering resistance by using additives and
additive
packages known in the state-of-the-art to be efficient. In addition, the skin
materials may
also contain various additives such as thermal and UV-light stabilizers,
pigments,
compatibilizers, processing aids, flame retardant additives, and other
functional
CA 02553186 2006-07-18
chemicals capable of improving processing of the materials and performance of
the
product. Foaming agents such as azodicarbonamide may be used to reduce the
density of
the skin material.
By way of example, the core material may be selected from the group comprising
of virgin thermoplastic polymer materials and elastomers and rubber including
but not
limited to Polyvinylchloride (PVC), Polyethylene (PE), Polypropylene (PP),
Polybutene
(PB-1), Polymethylpentene (PMP), Polyacrylates (PAC),
Polyethyleneterephthalate
(PET), Polybutyleneterephthalate (PBT), Polyethylenenaphthalate (PEN),
Ethylene-
Propylene-Diene Monomer Copolymers (EPDM), Styrene Butadiene Styrene (SBS),
Styrene Isoprene Styrene (SIS), Acrylonitrile Butadiene Styrene (ABS), or
Nitrite
Rubber, their copolymers, binary and ternary blends of the above, and filled
formulations
based on the above and other thermoplastic materials and elastomers with
mineral,
organic fillers, nanofillers, reinforcing fillers and fibers as well as
recycled materials of
the above polymers.
From the cost point of view, recycled and highly filled thermoplastic
materials
and recycled rubber (for example from tires) are preferable. The content of
mineral
fillers can be in the weight range from 5% to 80%.
In addition, the core materials may also contain various additives such as
thermal
and ultraviolet (UV) light stabilizers, pigments, compatibilizers, processing
aids, flame
retardant additives, and other functional chemicals capable of improving
processing of
the materials and performance of the product. Some flame retardants known to
have
negative effects on weather resistance of polymers can still be effectively
used in the core
material, the skin or capstock layer serving to protect the shingle from the
effects of the
weather. Chemical foaming agents such as azodicarbonamide may be used to
reduce the
density of the core material. Physical blowing agents, glass bubbles or
expanded
polymer microspheres may also be used to adjust the density of the core
material.
In making the products of this invention, the single layer 152 of skin or
combined
upper and lower layers 152 and 153, of the skin may comprise from 1% to 40% of
the
total thickness of the product, with the core inside the skin being thicker
between upper
and lower surfaces and comprising the remaining percentage of the total
thickness of the
product.
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CA 02553186 2006-07-18
Examples of making shingles in accordance with this invention are as follows.
Example 1
Pellets of a flexibilized polypropylene copolymer, 18S2A, available from
Huntsman Chemical, Salt Lake City, Utah, were combined in a Werner Pfleiderer
twin
screw extruder with calcium carbonate, Hubercarb Q3, available from J.M. Huber
Corporation, Atlanta, Georgia, and a stabilizer package, FS-811, available
from Ciba
Specialty Chemicals, Tarrytown, New York, using gravimetric feeders to obtain
a
mixture that was 49.25 wt% polypropylene, 50 wt% calcium carbonate and 0.75%
stabilizer package. This mixture was extruded as a strand and chopped into
pellets of
filled polypropylene for later processing.
Example 2
Pellets of Example 1 were dried and fed into a single screw extruder, MPM 3.5
inch in diameter, 24:1 LID, equipped with a flex lip die and extruded to form
a sheet. The
die was adjusted to produce an extrudate that was about 19 inches in width and
having a
profile with varying thickness across the sheet ranging from about 0.375
inches to 0.245
inches. The sheet was extruded onto a first conveyor belt having variable
speed matched
to the extnidate speed. The temperature of the sheet was about 380 F when
exiting the
die.
When a section of sheet 13 inches in length had been extruded, the sheet was
cut
from the die lip. While still hot, the section of 19"x13" sheet was carried to
a second
conveyor belt and transferred to and centered on the lower plate of a mold
having a size
of 18" x 12". Infrared lamps were provided above the conveyor to maintain the
temperature of the sheet during transfer. On reaching the lower mold plate,
the surface
temperature was about 300 F. The upper portion of the mold, having a surface
texture
designed to represent the surface texture of a natural slate, was brought into
contact with
the sheet on the lower plate and the mold was closed in a platen press with 20
tons
pressure to shape and form the sheet, with a slight excess of material being
squeezed out
of the mold.
Cooling was applied to the mold by means of water circulating cooling lines in
the mold plates to cool the formed sheet to a solid state. After about 1
minute, the mold
was opened to release a short cycle compression molded synthetic roofing tile.
The
17
CA 02553186 2006-07-18
synthetic roofing tile had cooled to a surface temperature of about 80 F on
the side that
had been in contact with the bottom plate and to temperature of about 120 F on
the
surface that had been molded by the top plate of the mold set. Excess material
and
flashing were cut off of the tile.
Example 3
Pellets of a flexibilized polypropylene copolymer, 18S2A, available from
Huntsman Chemical, Salt Lake City, Utah, were combined in a Werner Pfleiderer
twin
screw extruder with calcium carbonate, Hubercarb Q3, available from J. M.
Huber
Corporation, Atlanta, Georgia, using gravimetric feeders to obtain a mixture
that was 50
wt% polypropylene and 50 wt% calcium carbonate. This mixture was extruded as a
strand and chopped into pellets of filled polypropylene for later processing.
Example 4
Pellets of a flexibilized polypropylene copolymer, 1 8S2A, available from
Huntsman Chemical, Salt Lake City, Utah, were combined in a Werner Pfleiderer
twin
screw extruder with calcium carbonate, Hubercarb Q3, available from J. M.
Huber
Corporation, Atlanta, Georgia, and a stabilizer package, FS-811, available
from Ciba
Specialty Chemicals, Tarrytown, New York, using gravimetric feeders to obtain
a
mixture that was 79.25 wt% polypropylene, 20 wt% calcium carbonate and 0.75%
stabilizer package. This mixture was extruded as a strand and chopped into
pellets of
filled polypropylene for later processing.
Example 5
Pellets of filled polypropylene from Example 3 were dried and fed into a first
single screw extruder, MPM 3.5 inch in diameter, 24:1 LID, to provide core
material.
Separately, dried pellets of filled polypropylene from Example 4 and pellets
of gray toner
60Z2274 available from Penn Color, Doylestown, Pennsylvania, were fed using
gravimetric feeders to obtain a ratio of 2 wt% gray toner to 98 wt% filled
polypropylene
into a second extruder, Prodex 2.5 inch in diameter 24:1 L/D, to provide
capstock
material. The output of both extruders was fed through an adapter block and a
dual layer
coextrusion block to a flex lip die and coextruded to produce a sheet having a
core of
material from the first extruder bonded with a coextruded capstock provided by
the
second extruder, with the layer of capstock covering the top surface of the
layer of core
18
CA 02553186 2006-07-18
material.
The die was adjusted to produce an extrudate that was about 19 inches in width
and having a profile with varying thickness across the sheet ranging from
about 0.375
inches to 0.245 inches. The relative rates of extrusion from the two extruders
for the
capstock and the core layers were controlled such that the capstock thickness
was about
10% of the total thickness of the composite sheet, The sheet was extruded onto
a first
conveyor belt having variable speed matched to the extrudate speed. The
temperature of
the sheet was about 380 F when exiting the die,
When a section of sheet 13 inches in length had been extruded, the sheet was
cut
from the die lip. While still hot, the section of 19"x13" sheet was carried to
a second
conveyor belt and transferred to and centered on the lower plate of a mold
having a size
of 18" x 12". Infrared lamps were provided above the conveyor to maintain the
temperature of the sheet during transfer. On reaching the lower mold plate,
the surface
temperature was about 300 F. The upper portion of the mold, having a surface
texture
designed to represent the surface texture of a natural slate, was brought into
contact with
the sheet on the lower plate and the mold was closed in a platen press with 20
tons
pressure to shape and form the sheet, with a slight excess of material being
squeezed out
of the mold. The flow of material at the edges of the mold was such that the
capstock
thickness at the molded edges of the shape was maintained to be least 4 mils
over the
entire top surface of the piece, even at the edges.
Cooling was applied to the mold by means of water circulating cooling lines in
the mold plates to cool the formed sheet to a solid state. After about 1
minute, the mold
was opened to release a short cycle compression molded synthetic roofing tile
having a
core layer and a capstock layer. The synthetic roofing tile had cooled to a
surface
temperature of about 80 F on the side that had been in contact with the bottom
plate and
to temperature of about 120 F on the surface that had been molded by the top
plate of the
mold set. Excess material and flashing were cut off of the tile.
Example 6
Dried pellets of filled polypropylene from Example 3 were fed into a first
single
screw extruder, MPM 3.5 inch in diameter, 24:1 LID, to provide core material.
Separately, dried pellets of filled polypropylene from Example 4, pellets of
gray toner
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CA 02553186 2006-07-18
60Z2274 and black accent color pellets 68B282, available from Penn Color,
Doylestown,
Pennsylvania, were fed using gravimetric feeders to obtain a ratio of 2 wt%
gray toner, 1
wt% accent color pellet, and 97 wt % filled polypropylene into a second
extruder, Prodex
2.5 inch in diameter 24:1 LID, to provide capstock material. The output of
both extruders
was fed through an adapter block and a dual layer coextrusion block to a flex
lip die and
coextruded to produce a sheet having a core of material from the first
extruder bonded
with a coextnided capstock provided by the second extruder, with the layer of
capstock
covering the top surface of the layer of core material.
The temperatures in degrees Fahrenheit of the zones of the capstock extruder,
the
adapter, the coextrusion block and the die are noted below:
Barrel zone Adapter zone Co-Ex block Die zone
2 3 4 1 2 3 1 2 3
320 330 330 330 370 375 375 375 375 375
375
The die was adjusted to produce an extrudate that was about 19 inches in width
and having a profile with varying thickness across the sheet ranging from
about 0.375
inches to 0.245 inches. The relative rates of extrusion from the two extruders
for the
capstock and the core layers were controlled such that the capstock thickness
was about
10% of the total thickness of the composite sheet. The sheet was extruded onto
a first
conveyor belt having variable speed matched to the extrudate speed. The
temperature of
the sheet was about 380 F when exiting the die.
When a section of sheet 13 inches in length had been extruded, the sheet was
cut
from the die lip. While still hot, the section of 19"x 13" sheet was carried
to a second
conveyor belt and transferred to and centered on the lower plate of a mold
having a size
of 18" x 12". Infrared lamps were provided above the conveyor to maintain the
temperature of the sheet during transfer. On reaching the lower mold plate,
the surface
temperature was about 300 F. The upper portion of the mold, having a surface
texture
designed to represent the surface texture of a natural slate, was brought into
contact with
the sheet on the lower plate and the mold was closed in a platen press with 20
tons
pressure to shape and form the sheet, with a slight excess of material being
squeezed out
of the mold. The flow of material at the edges of the mold was such that the
capstock
thickness at the molded edges of the shape was maintained to be least 4 mils
over the
CA 02553186 2006-07-18
entire top surface of the piece, even at the edges.
Cooling was applied to the mold by means of water circulating cooling lines in
the mold plates to cool the formed sheet to a solid state. After about 1
minute, the mold
was opened to release a short cycle compression molded synthetic roofing tile
having a
core layer and a variegated capstock layer, the capstock having a base gray
color with
gray-black accent streaks simulating the color appearance of natural slate.
The synthetic
roofing tile had cooled to a surface temperature of about 80 F on the side
that had been in
contact with the bottom plate and to temperature of about 120 F on the surface
that had
been molded by the top plate of the mold set. Excess material and flashing
were cut off of
the tile.
Example 7
Example 7 was prepared similarly to Example 6, except that the gray toner
60Z2274 was omitted from the capstock and the capstock composition was metered
to
include 1 wt% of the accent color pellet and 99 wt% of the filled
polypropylene of
Example 3. The short cycle compression molded synthetic roofing tile having a
core layer
and a variegated capstock layer was produced, the capstock having a light
color with
gray-black accent streaks simulating the color appearance of natural slate.
Example 8
Example 8 was prepared similarly to Example 6, except that the temperature
profile of the capstock extruder was at a slightly higher temperature as shown
in the table
below.
Barrel zone Adapter zone Co-Ex block Die zone
1 2 3 4 1 2 3 1 2 3
350 350 350 350 370 375 375 375 375 375 375
The synthetic roofing tile having a core layer and a capstock layer was
produced,
the capstock having an even gray color, the accent color pellets having melted
out into
the mixture in the extruder.
Example 9
Example 9 was prepared similarly to Example 6, except that a different accent
color pellet, 60B281, available from Penn Color, was used with a capstock
composition
metered to 2 wt% gray toner 60Z2274, 2 wt% accent color pellet 60B281 and 96
wt%
21
CA 02553186 2013-01-09
filled polypropylene of Example 3. The 608281 had a higher softening
temperature than
the accent color pellet used in Example 6, so the temperature profile in the
capstock
extruder was modified as noted in the table below.
Barrel zone Adapter zone Co-Ex block Die zone
1 2 3 4 1 2 3 1 2 3
390 390 400 380 370 375 375 375 375 375 375
In the synthetic roofing tile of Example 9, having a core layer and a capstock
layer, the capstock had a base gray color, but also had gray-black spots where
the accent
color pellets had not melted sufficiently during the processing to produce the
streaking
effect.
It will be apparent from the foregoing that various other modifications may be
made in the process steps of this invention, in the apparatus, or in the
resultant roofing
shingle or tile of this invention, all within the scope of the invention as
defined in the
appended claims.
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