Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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SPECIFICATION
~ his invention relates -to insulation panels
or boards, and it particularly relates to insulation
boards that are most satis~actorily utili~ed ln roofing.
A roof construction generally comprises a
roo~ deck which may be made of various materials such
as wood, concrete, gypsum, steel, and the like, an
insulation barrier above the deck and a roof covering
which usually comprises at least one layer of asphalt
topped by a felt layer that is topped by ano-ther layer
Of asphalt. Generally about three such successive layers
are usedO Sometimes a layer of gravel or the like is
super-imposed on the top layer of asphalt.
~ he insula~ion barrier, itself, may comprise
one or more layers of insulating sheets placed on top of
each other at the building site or it may comprise a
prefabricated laminated board. ~he laminated type of
insulation board generally comprises a plastic foam
layer or core, which may be polurethane, polyisocyanate,
or the like, and has, at least on one side, a protective
or facing layer that may be either rigid or flexible
and is usually fire or flame retardant. When there are
two such protective layers, one on each side of the foam
layer, it is generally referred to as a "sandwich"
construction.
Plastic foams are used as core material in
sandwich panels because of low heat transmission, rigidity
light weight, moisture-proofness and chemical inertness.
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Facers that are commonly used lnclude expanded
perlite boards, metal foils, organic felt, plywood,
hardboard, cement-asbestos board, reinforced plastic,
tempered glass and glass fiber board. Since the
foam core is isolated from small ignition sources by
the facer, ignition resistance depends primarily upon
the degree of protection afforded by the facer.
The bottom facers should, in addition, be
capable of retarding ingress of fluids because this
type of insula~ion board is usually made by placlng the
bottom facers on a slatted conveyor belt and applying
an even distribution of liquid foam material thereon~
The foam, thereafter, expands and solidifies during
movement of -the conveyor. If the facers were to permit
bleeding through of the liquid foam material, this
material would stick and harden on the conveyor slatg,
thereby ma~ing the conveyor inoperative until cleaned~
The necessity for such constant cleaning would seriously
impair commercial production.
The ability to vent fluids such as vaporized
liquids and gases is impor-tant in this ~type of insulation
board. Such fluids may cause frothing or bubbling of
the asphalt when the hot asphalc is applied to the facing.
Evaporation of li~uid fluids, or expansion of entrapped
` gases and vapors, may cause asphalt blistering. Therefore,
there must be some means present ~or venting fluids such
as vaporize~ liquids or gases.
In order to vent such fluids it has been the
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usual practice to provide venting base sheets which
may he perforated, grooved or ribbed felts that ~orm
lateral escape channels for the fluids.
In accordance with the present invention, not
only are the usual venting sheets eliminated and their
function provided by the facing sheets themselves but
the porosity o~ the facing sheets are considerably reduced
(although still retaining sufficient porosity to permit
lateral venting of any vapors formed between the foam
layer and the roof covering) and the dimensional stability,
flexural strength, fastener pull-through strength, board
spanability, impact-resistance, wind-uplift performance
and surface traffic performance are considerabIy improved
in a manner which will become better understood by
reference to the following description when read in
conjunction with the accompanying drawings wherein:
Figure l, is a sectional view of an insulated
roof construction including the insulation board of
the present invention~
Figure 2, is a perspective view of an insulation
board embodying the present invention.
Figure 3, is a perspective view of a scrim
used in the present inventionO
Referring now in greater detail to the figures
of the drawing wherein similar reference characters refer
to similar parts, there is shown a roof construction,
generally designated 10, which includes a deck 12, here
shown as being made of concrete, an asphalt layer l~ above
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the deck, latera~ly butted insulation boards, generally
designated 16, which are joined at 18, and a roof
covering 20. Although not specifically shown, this
roof covering is preferably, but not necessarily, a
so-called BUR type formed by successive layers of
asphalt and roofing felt, usually three to four layers
of each.
~ he insulation boards 16, which are the subject
of the present invention, comprise a foam core 22, here
shown as being made of pol~urethane or polyisoc~ana-te
foam, a facer sheet 24 at the top of the foam core
and a facer sheet 26 at the bottom of the foam core.
Both of the facer sheets 24 and 26 are of the
same construction, and each comprises very fine glass
fibers bonded together with polyvinyl acetate; about 90%
of the facer being glass.
Attached to each facer sheet is a scrim, as
at 28 and 30. Both scrims are of the same size and
construction and scrim 30, shown in Fig. 3, is
illustrative of both.
~ he scrim shown in Fig. 3 comprises a glass
mat or sheet 32, of the same general construction as
the facers 24 and 26, but applied to one face of -the mat
32 is a grid formed by glass threads or s-trands 34. In
the scrim of Fig. 3, the glass threads are of about 4
pounds tensile strength and are arranged in a pattern
of ahout 1.8 ~-trands per inch in both directions. ~he
strands are coated and are bound at each contact point
with the same type of binder that is used in the production
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of the mat, which, in this instance, comprises polyvinyl
acetate (PVA). The strength of the scrim can be varied
by varying the strand diameter and grid pattern, bu-t
the pattern shown in Fig. 3 is the most preferable.
The scrims 28 and 30 are generally applied to
the respective facer sheets 24 and 26 after the facer
sheets have been formed, but while still wet; this
reactivates the PVA binder so that no additional binder
is required.
The scrims and their method of construction
do not form any part of the present invention except
insofar as they are used in the combination forming
the present insulation boards or panels.
The thickness of the facers may vary between
about 4 to 120 mils, although the preferable range is
between about 7 to 30 mils.
The glass fibers are treated with a non-wicking
agent such as a fluorcarbon, silicone or silanes. The
non-wicking agent is added after -the glass fiber product,
including both the facer and the scrim, is formed, but
while it is still in the wet state. The non-wicking
agent coates both ~he glass f~bers and -~he polyvinyl
acetate binder. This coating substantially prevents
absorption into or adsorption onto the fibers of any
liquids, whereby liquids that enter form beads on the
,
surfaces of the fibers.
In effect, the non-wicking agent is a liquid
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repellent which permits the facers to shed no-t only water 7
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but hot asphalt and any llquid foam ingredients.
However, there is sufficient absorbancv between the
mating surfaces of the foam and facer on the one side
and between the hot ~sphalt and facer on the other
side to create a bond. ~he important thing is that the
non-wicking agent prevents total ~leeding through of
the liquids because the pressure of the liquids is
less intense in the interior of the facing sheets
than at the interfaces with the other materials.
lQ ~he above-described facer structure, including
both the facing sheet and the scrim, al-thouyh capable
of repelling liquids r thereby preventing impregna-tion
and bleed-through by either hot asphalt or liquid
foam ingredients, is nevertheless porous because of
the fiber construction so that it will not trap any
vapors. Since it is porous, it permits lateral venting
of any vapors from between the foam layer and the roof
covering.
Facers or panels of -the above-described
construction, including the combination of facing sheet
and scrim, are commercially available and, in themselves,
do not constitute any part of the present invention
; except insofar as they are used in the present combination
to form the facers for insulation boards of the present
type.
Both the mat and strand portions of the scrims
28 and 30 have been described as made of ylass; however,
they may be constructed of other materials such as nylon,
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polyester, polyolefin, etc.. Nevertheless, the
glass is preferable because of its inorganic nature,
which makes it generally more flame-resistant
than organic polymers.
This invention has been illustrated in
th~ form of "sandwich" panels or boards wherein
the foam layer is covered with a facer on both sides, but
it may also embrace a board having a facer of this
type only on one side. The other side may have
another type of facer or none at all, depending on
the manner in which it is to be used. Furthermore,
although the invention has been described wi-th
particular relation to roofing, it i5 also possible
to utïlize these boards for other types of insulation.
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