Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to sheet like structures.
Already known are preformed sheet like structures
comprising a substrate for instance in the form of a
film of a water impermeable plastics material, and a
waterproofing pressure sensitive adhesive membrane, such
as of a bîtuminous composition, in particular a
rubber-bitumen mixture. Such substrates are supplied in
rolls with a width of 1 metre or so and can be laid side
by side, for instance on concrete, to provide a waterproof
layer thereon.
While it is also Xnown to use such structures
with aluminium as a substrate, it has hitherto been
necessary to limit the thickness of the aluminium to very
thin foils in order that the structure should not have
excessive rigidity. Such excessive rigidity would give
rise to arching and creasing of the aluminium based
structure upon laying, and result in the ~ormation of
channels which would permit the entry of water.
To avoid this problem, the structures employing
an aluminium substrate and a bituminous adhesive that
are known to date have been limited to widths of about
30 cm at most and employ only a thin aluminium foil, of
a thickness between 0.009 mm and 0.075 mm, mostly in the
region of 0.009 mm to 0.050 mm. However, structures of
this nature suffer from the disadvantage that the thin
aluminium substrates have low tensile strength, tear
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easily and also possess only limited resistance to
atmospheric corrosion, so limited, in fact, that it is
known for such structures to be supplied with a protective
coat of paint over the aluminium in order to improve the
resistance to weathering..
According to the present invention there is provided
a sheet like structure comprising an impressed metal
substrate with an array of projections on one side and
corresponding depressions on the other, the substrate
being flexible and having an adhesive membrane contiguous
thereto on one side.
We have found that such a structure displays
hitherto un-achieved flexibility for a useful metal
thickness, this being achieved by impressing the metal,
so that it is formed with an array of projections on one
side with corresponding depressions on the other, before
laminating it with the adhesive compound.
We have found that this arrangement allows the
structure, using relatively thick metal, to be laid flat
while still possessing easy bending or moulding
properties so as to achieve a particular shape if required.
For instance, to take one simple example, the structure
can be turned through a right angle, such as must be
formed between the upper surface of a flat roof and the
internal vertical surface of a parapet wall, and also
when tucking the structure at right angles into rebates.
The metal is a flexible metal, preferably aluminium,
and the adhesive membrane is preferably a waterproofing,
membrane, preferably bituminous and preferably a bitumen-
rubber mix.
To provide a useful thickness of metal, while still
allowing the additional flexibility offered as a result
of the invention, a meta] thickness of 0.125 to ~.25 mm,
preferably 0.15 mm is employed. The depths of the
depressions introduced by impressing can be from 0.1 to
10 0.8 mm, preferably 0.50 mm. The adhesive should be thick
enough to fill the depressions (or the gaps between the
projections) and offer a smooth surface for overall
adhesion to a surface to be covered. Its minimum
overall thickness should therefore be 1.5 mm, that is
when the maximum projection height is employed, so that
over the structure its smallest thickness will be
approaching 1.0 mm. However, a minimum adhesive thickness
of 1.8 mm, preferably,2.5 mm is better as it increases
the assurance of adhesion.
The structure of the invention may find many
applications, and can be provided in a variety of widths~
The structuresare particularly useful for application to
concrete surfaces, and for this application the membranes
are preferably pressure sensitive, that is to say they
enable the structures when pressed with normal hand
pressure against a concrete surface, without any prior
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treatment of the surface or membrane, to adhere to the
concrete. Thus, while priming and/or initial heating
may with advantage be performed, they are not essential
in order to adhere the membrane to concrete.
The membrane can be a layer of the adhesive alone
or the adhesive can contain reinforcing material, for
example a scrim of glass fibres or an organic polymer,
particularly to give the membrane mechanical strength,
if desired the membrane can contain a plurality of layers
of waterproofing pressure-sensitive adhesive (the
adhesive being the same or different in the different
layers), and the layers can be separated by reinforcing
material in the form of a sheet.
The structures as produced in a factory, stored,
and brought to the site for use are in the form of
laminates comprising the metal, the adhesive and,
usually a removable protective coating such a siliconised
paper, and are conveniently in the form of rolls.
On the one hand, the structures may be up to 12
2~ cm, typically 1 metre wide when for use in covering
large surfaces. On the other hand, structures of as
little as 65 cms in width may be provided.
Particularly when a waterproofing facility is
desired, bituminous adhesives are generally suitable
except where their colour is a disadvantage. If a
bituminous adhesive is used, it is preferably formed of
natural or synthetic rubber, virgin or reclaimed, blended
into bitumen to provide a smooth mix. The ratio by weight
of bitumen to rubber is preferably from 80:20 to 95:5,
especially about 90:10. Other types of contact aahesive
composition may include polychloroprene, butyl rubber,
oil-based mastics or compositions containing rosins or
rosin derivatives. Generally, suitable compositions have
softening points (measured by the Ring and Ball method)
of 60 to 110~C and penetration values of 150-300 at 25C
(100 g. 5 secs~ - Institute of Petroleum method).
A wide variety of materials can be used to provide
protective coatings in the structures of the invention.
Paper having a release coating thereon, e.g. siliconised
paper or p~per having a coating thereon of a vinyl
chloride polymer, is satisfactory. Other materials
include films of organic polymers, particularly vinyl
chloride polymers.
The structures of the invention can be prepared
without difficulty by techniques known per se. It is
preferred to use adhesives which are not solvent-based
and which are heated. Thus the adhesive may be bonded
to the substrate to form a uniform layer contiguous to
the substrate. If it is desired to incorporate a
sheet-like reinforcing layer in the membrane, this can
be achieved, for example by pressing a scrim into the
layer of adhesive.
The impression of the metal, which can be performed
using a solid metal roller cut with suitable profiles
and a resilient backing roller is preferably such that
the projections and depressions, which may be generally
rectangular, are regularly arranged in rows and columns.
This is found to allow notable flexibility and the facility
to bend the structure so that it keeps its shape. The
projections may be from 1 cm to 3 cm long and from 0 25
to 1 cm wide, preferably, being 2.2 by 0.5 cms. The
margins between the depressions may be from 0.5 to 1 cm,
preferably 0.7 cm wide.
In the sole Figure of the accompanying drawings is
illustrated a metal roller 10 cooperating with a
resilient backing roller 11. Between these rollers is
fed an aluminium sheet 12 which, as a result of the
action of the projections 13 on the metal roller, is
impressed with the pattern just described having on its
upper surface as shown depressions 14.
One application for structures of the invention
is as a roofing material. ~he structures can be unrolled
and adhered to such roofing undersurfaces as wood,
concrete or previously applied roofing felts and can give
absolute water tightness. Moreover, the structures of
the invention are particularly resistant to the action
of sunlight, in particular the ultraviolet co~ponent
thereof, thus offering much improved weathering to
conventional roofing materials. ~oreover, the metallic
surface acts as a reflectant, assisting therefore in
keeping the building below cool when used in hot climates.
The "bendability" imparted by the impressing of
the metal means that the structure can be used as a
vehicle for installing a metallic layer of significant
thickness in those positions, which has not readily
been possible hitherto except when lead has been used.
Further, structures according to the invention can
~ 10 be employed in such structures wherethe initially mentioned
waterproofing membranes are used at present, that is in
providing waterproofing membranes in concrete structures,
in particular underground structures or roof or bridge
decks where the structures are then covered, either by
more concrete or by a roofing or surfacing material.
There~is, in fact, a particular advantage offered in the
case of road and bridge building, namely that hot asphalt
can be poured directly ontothe structure without deleterious
effect on the waterproof seal and the asphalt will be most
satisfactory keyed to the impressed surface of the
structure thus reducing slipping between the road surface
and the underlying structure.
Where a waterproofing property is desired, as in many
of the applications envisaged, a waterproofing, preferably
2~ rubber-bitumen membrane should be employed. The thicker
the membrane, the better the waterproofing properties,
and a thickness of up to 0.5 cm can usefully be employed.
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