Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
The subject of the present invention is an impermeable
and/or insulating material in sheet form, designed primarily
for use in a chemically or biologically damaging environment, and
particularly in environment subject to atmospheric pollutants such
as acids, bases, solvents and other precipitants which may be
deposited on the material.
DESCRIPTION OF PRIOR ART AND TECHNIQUES
Because of the great variety of gaseous,liquid, or solid
precipitants discharged into the atmosphere in a continuous or acc-
idental manner, there exists a major universal problem with respect
to the continuing impermeability of roofing materials.
Normal types of bituminous impermeable sheeting are
severely damaged by deposits of aromatic or chloric solvents which
may result from a number of industrial processes, the damaging
action resulting from the progressive dissolution of the bitumen.
In addition, oxidizing deposits (sulphurous gas and varous acids)
rapidly lead to a crumbling of the bitumen and it accordingly be-
comes necessary to frequently restore the impermeability of the
surface.
Sheets of impermeable bituminous material covered by a
sheet of aluminum are also rapidly attacked by deposits of sul-
phurous gas as well as by alkaline or acid deposits.
Materials for protecting bitumen which are capable of
ensuring the continuity of such protection in the event of cor-
rosive attack have already been proposed, such proposals including
for example sheets of stainless steel. However, stainless steel
is very expensive and has a very pronounced rigidity.
A proposal has also been made to use a coating of protect-
ive plastic. However, to apply such a coating in situ is a very
~0 difficult operation. Furthermore, plastic film contains plastic-
zers which tend to migrate to the surEace and to create a sticky
layer to which dust will adhere.
OBJECT OF THE INVENTION
It is an object of the present invention to reduce themany drawbacks of the known types of roof coverings.
This is achieved in accordance with the invention by
a flexible, composite, impermeable and/or insulating covering of
the type which comprises a bituminous underlayer covered with a
protective layer resistant to the effects of weather and various
atmospheric pollutants whether they be chemical or biological, and
wherein the protective layer consists essentially of a continuous
sheet of synthetic material previously stabilized with respect to
shrinkage.
The present invention combines a plastic sheet, free of
plasticizers and resistant to corrosive agents, wi-th an impermeable
bituminous sheet which results in a sheet or panel that is per-
fectly resistant to all types of external attack, while at the
same time still being capable of being laid as a roof covering by
traditional methods.
2~ However, during the process of manufacturing an imper-
meable sheet, plastic sheeting is subject toheat shock and will
consequently shrink considerably when it is applied to the bitum-
inous layer due to the phenomenon oE "creeping". The resul-t is a
gap in the protective covering and a risk of tension at the ends
of the sections placed together.
In accordance with the invention, the sheet of plastic
has to be stabilized with respect to shrinkage which begins when
it is applied.
The present invention proposes s-tabilization of the
plastic sheet by gluing it against a rigid backing such as for
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example a sheet of glass or an asbestos fibreboard.
~ lowever, there is the risk of incompatibility between
the bituminous underlayer and the adhesive used for this operation.
Furthermore, there is also the risk of air bubbles being trapped
beneath the plastic sheet which can result in blisters or pimples.
In accordance with a feature of the invention the sheet
of plastic is glued against a continuous backing support with the
aid of a reactive adhesive, the adhesive of course having to be
perfectly compatible with the two elements being glued together,
the film of plastic and the backing support. The continuous back-
ing prevents direct contact being made between the glue and the
bitumen and therefore the avoidance of the phenomenon of incomp-
atibility mentioned above.
A preferred and advantageous method is to have the back-
ing to be glued to the plastic made of a metallic sheet, prefer-
ably aluminum, and to have this sheet of a thickness which may vary
within a non~restrictive range, for example from 9 to 200 microns,
more specifically wi-thin the range of 20 to 80 microns.
One method for gluing the sheet of plastic against its
backing support could be, for example, as follows:
- coating the backing support with a reactive adhesive
dissolved in a solvent;
- evaporating the solvent in an oven;
- applying the plastic film by means of press under
ambient temperature in order to prevent the plastic film from being
deformed, the binding achieved being stronger than -the inherent
cohesion of the sheet of plastic.
Any protective film made of synthetic thermoplastic or
elastomeric material can be used in this method, provided that it
meets the requirements for protection with respect to atmospheric
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damage. An advantageous method is to use a thin film of poly-
vinyl chloride, having a thickness ranging between 10 and 100
microns.
It is advantageous for the film to have an optimal thick-
ness o 37.5 microns. It must be deformable, resistant to atmos-
pheric attack, chemically inert and preferably coloured throughout
without plasticizers.
In accordance with traditional techniques used to the
field of impermeable material production, the sheeting formed may
be corrugated or embossed in order to reduce the areas of expansion
and contraction before being coated with bitumen (whether strength-
ened or not) by standard methods of manufacturing roof coverings.
The stability of the composition according to the present
invention may be verified by subjecting it to a given thermal cycle,
to demonstrate that after various phases of the cycle the compound
has undergone neither expansion nor contraction.
The composite sheet made up in this way can be glued with
a coating of bitumen onto any surface suitable for a covering of
impermeable material and prepared according to conventional methods.
Preferably a narrow strip along one edge of the bitumen-
ous underlayer will not be coated with the plastic film/support
la~er; this narrow strip being laterally covered by an adjacent
partially overlapping roofing section.
In order to prevent the bitumen used as adhesive from
sticking to the compound of the adjacent sections it is advantag-
eous to coat the latter with soapy water as far as the adhesive
extends, the bitumen which has overlapped then being capable of being
unstuck from the plastic film without damaging the film. The edges
at the ends of the sections are protected either by a composition
that is resistant to chemical attack, such as polyurethane for
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example, or by self-adhesive bands of the compound described above,
or by any other appropriate method.
The results achieved in this way is an impermeable cover-
ing which has the following advantages;
- the impermeable bitumen is protected against various
types of atmospheric damage,
- the protective covering is both durable and pleasing
in appearance as an integral part of -the architecture of the build-
ing and of the site;
- the method of application is easy and there is no
risk of tearing or other damage which could create ho]es;
- the compound can be adapted to fit any dimensional
variation of the supporting structure;
- the outer surface can be cleaned and is in a sense
self-cleaning through the action of rain;
- the combined sheet is resistant to fire by virtue of
the metallic backing support; alternatively, it would be possible
if so desired to use a fire-proof plas-tic film.
The composite product, consisting of the bituminous under-
layer and the backing support/~ilm may be coated on its under sur-
face with an adhesive substance in either a thin or a thick layer,
which may vary within a range of several microns up to several
millimeters, with or without reinforcement which will permit its
use in areas where the plastic film could be damaged by fire after
it is applied, as well as in cases where it cannot be worked with
the normal techniques used with melted bitumen.
For these types of applications, the adhesive substance
may be protected with the aid of a layer of paper and crimped,
siliconed polyethylene which can be removed after it is applied.
~0 With the corrugating giving it the capacity for expansion
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without tension the product can be used for coverlng gaps, for
dressingup chimney stacks, roof gu-tters, joists or other external
protuberances and it will produce an impermeable covering that is
esthetically pleasing without having to be painted or otherwise
coated.
In addition, the product in accordance with the invention
can also be used as an insulating sheathing on elements of machines
or other structures which are subject to atmospheric damage.
Finally, an aspect of the invention which should also be
included is the production of the plastic film and its backing sup-
port by means of techniques related to the process of combining
by gluing. Thus, this compound may be produced by extrusion, coat-
ing with plastisols or any method of projection before polymeriza-
tion on the metallic backing support, the thickness of -the film
obtained being variable between 1 and 500 microns.
~0
