Note: Descriptions are shown in the official language in which they were submitted.
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A PREFABRICATED ACRYLIC SEALING MATERIAL AND ITS APPLICATION FOR
SEALING COVERINGS AND UNDER-COVERINGS
Field of the Invention
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The invention relates to a multilayer prefabricated acrylic
sealing material in the sheet form, and more particularly to the
application of this material for sealing coverings ar.d under-coverings.
Background of the Invention
Various multilayer prefabricated acrylic sealing materials in the
sheet form have already been proposed for sealing coverings of
buildings, and notably of platform roofs. Thus, patent FR-A-1 483 973
discloses a water-tight covering element consisting or a sheet made of
a sealing plastic or elastic membrane laminated on a flexible sheet of
open cell foam, said element being glued on the foam side by means of
an appropriate glue on the support which has to be sealed. Patent
FR-A-2 362 981 relates, amongst others, to an acrylic sealing material
formed of a layer of a textile material coated on only one of its faces
with a water-tight layer of an acrylic polymeric material, said sealing
material being laid by glueing of the txtile side by means of an
appropriate adhesive on the support which has to receive the sealing
material, in such manner that a central portion of the textile layer is
not impregnated, neither by the adhesive used for glueing nor by the
acrylic polymeric substance of the water-tight layer.
An under-roofing material which resists impacts, which is water-
tight and permeable to air and steam, for roofings in discrete elements
such as tiles or slates overlapping each other, is also known
(FR-A-2 467 934 and FR-A-2 517 726), said material being made of a non
woven web of a polymeric substance such as polypropylene, polyethylene,
polyester, vinyl polymer, coated in the hot state on one face
(FR-A-2 467 934) or on both faces (FR-A-2 517 726) with a filler added
bitumen (or asphalt) film in a quantity just sufficient for having a
structure with microholes or microcracks when cooled down, opposing the
passage of a liquid by capillarity but allowing the passage of air or
steam.
In spite of their interesting performance, the multilayer
prefabricated materials proposed either for sealing building coverings
or also as materials for under-coverings or under-roofings still suffer
from some deficiencies. In particular, the material disclosed in patent
FR-A-1 483 973 has a small resistance to static punching, as determined
according to standard NF P 84352, and moreover the foam open cells
represent a major fault when there is a leak (sponge effect and
accumulation of large quantities of water). For the bituminous material
for under-roofings of patents FR-A-2 467 934 and FR-A-2 517 726, the
well known sensitivity of bitumen to ultraviolets has for consequence
that the covering has to be made without delay, the product also
loosing part of its flexibility when the weather is cold.
Objects and Summary of the Invention
The invention provides a prefabricated acrylic sealing material in
the form of a multilayer sheet, which can be used for sealing coverings
of buildings or as a material for under-coverings or under-roofings and
which, in some of these applications, allow remedying the deficiencies
of the sheet materials used till then.
The prefabricated acrylic sealing material according to the
invention consists in a multilayer sheet including a textile support
layer, a foam layer made of an acrylic polymeric substance and a binder
layer of an acrylic polymeric material, and is characterized in that
each layer is bonded to one at least of the two other layers in such
manner that the foam layer is always in contact with the textile
support layer, the thicknesses of the various layers corresponding to
surface masses of these layers ranging from 30 to 300 g/m2 for the
textile support layer, from 10 to 100 g/m2 for the foam layer and from
50 to 2000 g/m2 for the binder layer.
The textile support layer may consist of a woven web, or
preferably a nonwoven web of natural or synthetic organic fibers, for
example fibers in a polymeric material such as polypropylene,
polyethylene, polyamide and notably aromatic polyamide, polyester,
vinyl polymer or even inorganic fibers, for example glass fibers.
The acrylic polymeric material used for making the foam layer is
based on at least one polymer chosen amongst the acrylic ester
homopolymers, the acrylic ester copolymers between themselves and the
copolymers of one of several acrylic esters with a minority quantity of
one or several ethylenically unsaturated monomers such as the
ethylenically unsaturated carboxylic acids and their anhydres, notably
acrylic acid, methacrylic acid, maleic anhydride, cross-linking
monomers such as the acrylic amides, for example acrylamide,
methylolacrylamide, the vinyl aromatic monomers such as styrene,
whereby said copolymers can be statistic copolymers, transplanted
copolymers and even sequenced copolymers. The acrylic esters which are
part of composition of the aforementioned copolymers are advantageously
acrylates or alcoyl methacrylates, with the alcoyl radical in C1 to C18
and preferably in C2 to C8, notably ethyl, butyl, hexyl, ethyl-2-hexyl,
and can carry possibly at least one active group, for example a
hydroxyl or amino group.
The polymer material from which is formed the binder layer is
based on at least one acrylic polymer chosen amongst the homopolymers
and copolymers hereabove defined as likely to form the foam layer.
The polymer or polymers forming the polymer material of the binder
layer can be identical or partly identical to the polymers forming the
polymeric material of the foam layer, on on the contrary be different
to the latter polymers.
In addition to its polymer component, each of the foam and binder
layers can also include various additives, for example fillers such as
kaolin or calcium carbonate, pigments, dyes, flame retardants, wetting
agents, fungicides, aligicides, said additives being associated with
the polymer component of the layer in consideration, in quantities
corresponding to those usually advocated for their use.
Advantageously, the binder layer of the multilayer sheet forming
the sealing material includes a few per cent, for example from 2 to 5
per cent by weight of a granular filler, notably glass, silicate or
calcium carbonate microballs, the size of the grains of which ranges
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from about 150 ~m to 600 ~m, which allows imparting a microrugosity to
the binder layer surface.
According to a first embodiment, the sealing material according to
the invention has its foam layer interposed between its textile support
layer and its binder layer, the thicknesses of said layers
corresponding to surface masses ranging from 30 to 300 mg/m2 for the
textile support layer, from 10 to 100 g/m2 for the foam layer and from
1000 to 2000 g/m2 for the binder layer. In particular, in this first
embodiment, the foam layer has a cellular gradient from the textile
layer to the binder layer, meaning that it possesses a number of cells
which decreases from the textile layer when getting nearer to the
binder layer in order to form, in contact with said binder layer, a
continuous and closed surface. The multilayer sheet sealing material
obtained according to the aforementioned embodiment is usable for
sealing coverings, notably platform roofs, such a material being
totally water-tight, having a good behaviour to ultraviolets, an
excellent behaviour at high temperatures (in particular no flow up to
about 120-130C) and a good flexibility at low temperature (no breakage
when bent on a mandrel having a diameter of 10 mm at -35C). The laying
of said sealing material on the support for receiving it is carried out
by glueing, with the textile side of the material facing the support,
by means of any appropriate glue, for example an acrylic glue in
aqueous dispersion or in the form of a solution in a solvent, after
overlapping the free edge of a sheet which has just been laid by about
10 cm on the adjacent sheet which is being laid.
In order to improve the interdependence of the adjacent sealing
sheets during the abovementioned laying operation, a marginal zone of
the textile support layer which extends along a longitudinal edge of
the sealing sheet can be substituted by a layer of substantially equal
thickness of a thermally activable adhesive, for example a hot melt
adhesive, the width of said zone being for example of 5 to 10 cm. When
providing the tightness of a covering, the connection between two
adjacent sealing sheets is then carried out by overlapping the two
longitudinal free edge of the sealing sheet which has just been laid
with the thermally activable adhesive zone of the textile support layer
of the sealing sheet which is being la:id, once the adhesive of said
zone has been activated by heat.
According to a second embodiment of the sealing material according
to the invention, the thicknesses of the layers forming the multilayer
sheet correspond to surface masses ranging from 30 to 300 g/m2 for the
textile support layer, from 10 to 100 g/m2 for the foam layer and from
50 to 500 g/m2 for the binder layer, said layers being disposed in such
manner that the foam layer is interposed between the textile support
layer and the binder layer, or that the textile support layer is
interposed between the foam layer and the binder layer.
The sealing material obtained according to the second embodiment
can be used as a material for under-coverings (under-roofings), such a
material being perfectly water-tight under a pressure of 1500 Pa and
having a large permeance to water steam (at least 100 g/m2 and for 24
hours according to standard NF T 30-018), with a good behaviour to
natural ageing and a good resistance to W s, resisting to the fall of
objects or persons and offering, if desired, an anti-sliding surface.
The sealing sheets forming the under-roofing or under-covering
material are placed between the support of the tiles or slates and the
framework, with the binder layer side opposite the tiles or slates, ln
such manner that their longitudinal edges is substantially oriented
along the line of greatest slope of the roofing and that the free
longitudinal ed8e of the sheet which has thus been laid is overlapped
by about 10 to 20 cm of the textile support layer or of the foam layer,
according to case, of the adjacent sheet which is being laid.
The multilayer sheet sealing material according to the invention
can be made by any method allowing providing a sheet having a
three-layer structure which is characteristic of the invention.
Advantageously, the sheet according to the invention is produced by 2
coating technique used in a traditional manner and including a coating
of the textile support chosen by means of a precursor of the foam
layer, said precursor consisting in a drying operation of the foam
layer, then of a coating, according to case3 of the free surface of the
dried foam layer of the free surface of the textile support layer by
means of a precursor of the foam layer, said precursor being made of an
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acrylic composition in an aqueous dispersion, and finally a drying of
the binder layer.
The formation of the thermally activable adhesive marginal zone
along a longitudinal edge of the textile support layer of the sealing
S sheet can be obtained by abrasion of the textile sheet and by extrusion
of the adhesive on the site thus formed by abrasion of the textile.
The foamed acrylic composition in an aqueous dispersion which
forms the precursor of the foam layer is prepared, in a conventional
manner, by first preparing an aqueous dispersion of the ingredients,
meaning the acrylic polymeric material and the various additives,
chosen as to form the composition, then by subjecting this dispersion
to a sufficient mechanical agitation so as to bring said dispersion in
the foam form~
Likewise, the aqueous dispersion of the acrylic binder, forming
the precursor of the binder layer, is obtained by the traditional
dispersion techniques in an aqueous phase, of the ingredients, meaning
the acrylic polymeric material and the various additives, chosen for
forming the acrylic binder.
The various operations, viz. dispersion, coating, drying, abrasion
of the textile layer, extrusion of the thermally activable adhesive,
which are found in the preparation of the sealing sheet can be carried
out by using the various devices known to this effect.
Detailed Description of some embodiments
The invention is illustrated by the following examples which are
non limiting.
Example 1
Two series A and B of sealing sheets according to the invention
and usable as under-roofing material have been prepared by coating.
Series A:
The sealing sheets of this series were made of a nonwoven web of
polypropylene fibers having a surface mass equal to 110 g/m2, coated on
one face with an acrylic foam layer based on an ethyl acrylate
terpolymer. an acrylic acid and N-methylolacrylamide, said foam layer
having a surface mass of 50 g/m2 and being coated on its other face
with a layer of acrylic binder based on an ethyl acrylate and methyl
methacrylate copolymer and filled, according to case, from 2 to 5 per
cent by weight of the binder, with glass or silicate microspheres
having a diameter of about 300 ~m, said binder layer having a surface
mass of 300 g/m2.
Series ~:
The sealing sheets of this series were made of a nonwoven web of
polyester fibers having a surface mass of 130 g/m2 coated on one face
with an acrylic foam based on the terpolymer used for preparing the
sheets of Series A, said foam layer having a surface mass of 20 g/m2
and being coated in turn with a layer of acrylic binder based on an
ethyl acrylate and methyl methacrylate copolymer and filled, according
to case, with 2 to 5 per cent by weight of the binder, with calcium
carbonate grains having a size grading from 200 to 500 ~m, said binder
layer having a surface mass of 300 g/m2.
The sealing sheets thus produced were totally water-tight under a
pressure of 1500 Pa and had a permeance to steam, according to NF T
30-018, of about 100 to 110 g/m2 and for 24 hours. ~oreover, they had a
good behaviour to UV and a good fire resistance, and they also offered
a satisfacotry anti-slide surface (free surface of the binder layer).
Ex~mple 2
Two series C and D of sealing sheets according to the invention,
usable for sealing coverings (platform roofs), have been prepared by
coating.
Series C
The sealing sheet of this series were made of a nonwoven web of
polyester fibers having a surface mass of 150 g/m2 coated on one face
with an acrylic layer based on the terpolymer used in Example 1, said
foam layer having a surface mass of 50 g/m2 and being coated in turn
with a layer of an acrylic binder based on a butyl acrylate and methyl
methacrylate copolymer mixed with a butyl acrylate and styrene
copolymer with 20 per cent by weight of styrene and filled, according
to case, with 2 to 5 per cent by weight of binder, glass or silicate
microspheres with a diameter of about 300 ~m, said binder layer having
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a surface mass of 1700 g/m2.
Series D
The sealing sheets of this series were made of a nonwoven web of
polypropylene fibers having a surface mass of 136 g/m2 coated on one
S face with a layer of an acrylic foam based on the terpolymer used in
Example 1, said foam layer having a surface mass of 20 g/m2 and being
coated in turn with a layer of thermally cross-linked acrylic binder
based on a butyl acrylate, methyl methacrylate and N-methylolacrylamide
terpolymer, said binder layer having a surface mass of 1700 g/m2. Each
sheet carried also a coating of a hot melt adhesive on a marginal zone
of 5 to 10 cm formed by abrasion of the nonwoven layer along a
longitudinal edge of the sheet, this zone provided with the holt melt
adhesive being intended for making easier the junceion of adjacent
sealing sheets (breadth to breadth junction).
The covering sealing sheet of Series C and D are totally water-
tight under a pressure of 0.6 ~Pa. ~oreover, they have an excellent
behaviour to UVs, a good behaviour to flowing (flowing temperature over
120C) and a good flexibility at a low temperature (no breakage when
folded on a mandrel with a diameter of 10 mm at -35C). ~oreover, the
sheets of Series C which include a surface granular filler of the
binder layer also offer a satisfactory anti-sliding surface.
Of course, the invention is not limited to the embodiments
described, and it encompasses all the various variants thereof which
may be defined by those skilled in the art and which are within the
scope of the invention.
