Note: Descriptions are shown in the official language in which they were submitted.
CA 02369796 2001-10-08
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TITLE: IMPREGNATED FOAM MATERIALS
THIS INVENTION relates to impregnated foam materials and their use to seal
surfaces against the entry of air, water, dust and the like.
Elastic and resilient materials are often used as sealing materials against
moisture,
draughts and dust. A particular application is in the construction of roofs
and walls
of a building with, for example, overlapping formed metal or cement or similar
sheets where a strip is inserted in the overlap of two adjacent sheets to
provide the
required sealing therebetween. Such sealing strips are also usually required
between the underside of such sheets and their supporting battens or rafters.
Similar strips are also used to seal adjacent tiles or similar on a roof and
between
the underside of the tile and its supporting batten or rafter.
Of course, if there is any unevenness or roughness present on either of the
surfaces
IS to be sealed, the sealing material must be flexible in order to conform to
the surface
that is being sealed. Favoured sealing strips are open-pore, absorbent
materials
impregnated with a substance which, on compression, bonds the open cells of
the
material together and simultaneously effects the required sealing.
It is already known that, by impregnating a flexible foamed plastics material
with
certain bituminous substances, a sealant is obtained which can provide joint
sealing
properties. Typical foams include a reticulated, flexible polyester-
polyurethane
foam having a three-dimensional uniform open cell structure which can be
impregnated with a bitumen emulsion.
It is the bitumen emulsion which prevents the passage of air, water etc.
through the
foam material and thus it is advantageous to maximise the amount of bitumen
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absorbed by the foam material. It was generally accepted in the art that
typical
maximum bitumen concentrations were about 120 kg/m3.
However, as described in the present applicant's earlier Australian Patent No.
663,480, the concentration of bitumen present in these foam materials can be
increased to about 225 kg/m' (dry weight).
It has know been found that the concentration of bitumen in these foam
materials
can be increased further to in excess of 600 kg/m'.
Thus, according to a first aspect of the present invention, there is provided
a sealing
material, said material including a bitumen-impregnated foam characterised in
that
said bitumen is present at greater than 225 kg/m3.
Preferably, said bitumen is present at a concentration in the range between
230 kg/m3 to in excess of 600 kg/m3.
Preferably, said foam is an open cellular foam each cell of which is coated
with
said bitumen.
More preferably, said foam is a polyether-polyurethane foam.
In use, said sealing material is preferably in the shape of an elongated
strip, said
strip, optionally, having a configuration on one or more faces thereof which
conforms to the shape of the surfaces to be sealed.
Of course, the sizes of said strips can vary dependent upon their application
but a
preferred strip will typically have a base width of 40-SOmm and a height of 30-
75
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Said sealing material can optionally be coated on its exterior surface with an
acrylic
emulsion composition.
By coating the material with said acrylic emulsion composition, the bitumen is
protected from degradation by exposure to ultraviolet and other radiation. A
further
advantage of the acrylic emulsion coating is that it renders the material fire
retardant.
Said composition may also be coloured to coordinate with an exterior colour of
the
surfaces to which it is applied.
T'he preferred method of manufacturing a sealing material as hereinbefore
described
is to:
first saturate said foam with said bitumen; and
remove any excess of said bitumen from said thus-saturated foam.
The foam need not be initially saturated with neat bitumen but a composition
based
on bitumen may be used. Suitably, the bitumen is selected from the group
including bitumen emulsion, hot bitumen and kerosene-diluted bitumen. A
preferred bitumen is a bitumen emulsion comprising 40% bitumen and 60% water.
In the preferred use of bitumen emulsion, after removal of excess emulsion,
the
water is allowed to evaporate off.
Any suitable means known in the art can be used to saturate the foam and then
remove the excess bitumen. For example, the foam could be dipped into a
bituminous composition for a suitable period, removed from said bituminous
composition and excess bitumen allowed to drain from the foam. As an
alternative
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to allowing the bitumen to drain from the foam, the saturated foam could be
squeezed to remove the excess bitumen, for example, by passing between
multiple
rollers. In these embodiments, the thus-squeezed or drained foam could be re-
dipped into the bituminous composition, removed therefrom and again squeezed
or
drained to remove the excess bitumen. These dipping and removing excess
bitumen
procedures could be repeated several times until the desired concentration of
bitumen in the foam is obtained.
According to a third aspect of the present invention, there is provided a
method of
sealing an overlap between two adjacent surfaces, said method including
inserting
in said overlap a sealing material as hereinbefore described.
In use, the sealing material is pressed into contact with the surfaces to be
sealed. If
inserting into a pre-existing gap, it is advantageous to apply some pre-
compression
before inserting the sealing material into the gap in order to accommodate any
variations in spacing in that gap. In other cases, where, for example,
overlapping
roofing or wall sheets are to be bolted together, the nature of that assembly
will
automatically apply a sufficient compression.
Preferred embodiments of the present invention will now be described with
reference to the following examples.
A polyether-polyurethane foam termed "light duty" under Grade No. L27-180 as
supplied by JOYCE FOAM PRODUCTS was cut into four (4) strips, each strip of
dimensions approximately 2m x 40mm x 30mm, and labelled Sample lA, Sample
2D, Sample 3D and Sample 4D. In all of the examples below, the bituminous
composition was an emulsion of 40% bitumen and 60% water.
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Sample lA strip was dipped into the bituminous composition for a brief period
and
then removed from the solution. The strip was allowed to drain and air dried.
The
foam was analysed for bitumen content and found to be 441.0 kg/m3.
Sample 2D strip was dipped into the bituminous composition for a brief 'period
and
5 then removed from the solution. The saturated foam was then squeezed between
multiple rollers to remove excess bitumen adhering to the foam and air dried.
The
single-dipped foam was again dipped into the bitumen composition for a further
brief period, removed therefrom, passed between the multiple rollers and air
dried.
The thus double-dipped foam was analysed for bitumen content and found to be
- 313.7 kg/m3.
Sample 3D strip was dipped into the bituminous composition for a brief period
and
then removed from the solution. The saturated foam was then squeezed between
multiple rollers to remove excess bitumen adhering to the foam and air dried.
The
single-dipped foam was again dipped into the bitumen composition for a further
brief period, removed therefrom, passed between the multiple rollers and air
dried.
The now double-dipped foam was again dipped into the bitumen composition for a
further brief period, removed therefrom, passed between the multiple rollers
and air
dried. The thus triple-dipped foam was analysed for bitumen content and found
to
be 469.1 kg/m3.
Sample 4D strip was dipped into the bituminous composition for a brief period
and
then removed from the solution. The saturated foam was then squeezed between
multiple rollers to remove excess bitumen adhering to the foam and air dried.
The
single-dipped foam was again dipped into the bitumen composition for a further
brief period, removed therefrom, passed between the multiple rollers and air
dried.
The now double-dipped foam was again dipped into the bitumen composition for a
further brief period, removed therefrom, passed between the multiple rollers
and air
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dried. The now triple-dipped foam was again dipped into the bitumen
composition
for a further brief period, removed therefrom, passed between the multiple
rollers
and air dried. The thus quadruple-dipped foam was analysed for bitumen content
and found to be 603.5 kg/m3.
The present invention can thus provide foam materials impregnated with bitumen
to
concentrations in excess of 600 kg/m3. When the foam material is a polyether
polyurethane, a much longer life of the sealing material is possible - of the
order of
four-fold over a polyester-polyurethane. Such impregnated materials with their
hitherto unknown high concentrations of bitumen offer improved sealing against
moisture, draughts and dust.
It will be appreciated by those skilled in the art that the above examples are
illustrative only of the present invention and that modifications and
alterations can
be made without departing from the inventive concept as defined in the
following
claims.
