Note: Descriptions are shown in the official language in which they were submitted.
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FLASHING SHEET
The present invention relates improved flasting
sheets suitable for use, in building construction, as
materials which provide watertight coverings over the
various non-flat parts of the roof and walls of the building
such as the edges and the corners of the roof and walls,
the areas around roof drains and the areas around roof
protrusions te.g. vent pipes, skylightsJ. The term "bitu-
minous" and "bitumen", as used hereinbelow, may be replaced
by the term "asphalt".
Heretofore, as flashing or roof flashing materials
for providing watertight coverings over the above-mentioned
various non-flat parts of the roof and walls, bituminous
roofing or waterproofing membranes, vulcanized rubber
sheets, unvulcanized rubber sheets, synthetic resin sheets
and the like have been generally used. These conventional
flashing sheets either do not have any base sheet or have
a base sheet of such material as paper, a film of synthetic
polymer, a metal foil, a woven or non-woven fabric of
organic or inorganic fiber and the like. However, since
these conventional flashing sheets are poor in expandability
or stretchability or are of high modulus of stretch even
if they are expandable or stretchable, these flat sheets
cannot be, without cutting or folding, applied onto the
various non-flat parts or substrates having solid or three
dimensional shapes without causing water leakage problems.
For this reason, these conventional flashing materials have
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been applied on the above-mentioned non-flat parts of the
roof and wall elements as illustrated in Figs. 1 and 2.
Fig. 1 is an explanatory view illustrating a conventional
flashing seal for the area around roof drains. Figs. 2A
and 2B are explanatory views illustrating conventional
flashing seal for, for example, a corner on the top of a
building. As illustrated in Fig. 1, when the flashing
seal is applied to an area 11 around a roof drain 12,
several conventional flashing sheets 13 which are cut into
appropriate sizes are partially overlapped with each other
and adhered onto the area 11. Referring to Figs. 2A and
2B, in the case where the flashing seal is applied to a
corner of, for example, the top of a building, a cut line
15 is provided in a conventional flashing sheet 14, so
that the flashing sheet 14 can be folded to a form 16 that
fits the shape of the corner to be covered. The folded
sheet lS is adhered to the substrate by means of any
conventional adhesive.
The above-mentioned application processes of the
conventional flashing sheets are very troublesome and, in
order to prevent the occurence of water leakage through
the flashing seals, very careful attention and high skill
of the workers are required. However, in fact, many water
leakage problems at the flashing seals have been caused by
improper watertight coverings.
Some conventional flashing sheets composed of
unvulcanized rubber and having no base sheet have a low
modulus of stretch and a high expandability. To a person
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not skilled in the art, it may appear that these flashing
sheets could be applied onto non-flat parts having various
three dimentional shapes. However, when these flashing
sheets are deformed so as to be adhered onto the substrates
of the non-flat parts, local deformation of the flashing
sheets occurs and the thicknesses of the flashing sheets
become non-uniform. In addition, the mechanical strength
of these locally deformed portions of the flashing sheets
becomes poor and the waterproofing function of these
flashing sheet becomes insufficient, from a practical
point of view.
Furthermore, it has also been proposed to use
flashing sheets which are previously formed or shaped,
from synthetic rubbers and synthetic resins, into forms
that fit the shape and the dimensions of the non-flat
parts to be covered by the flashing sheets. It may appears
to a person not skilled in the art that these previously
formed flashing sheets could be easily applied to the
above-mentioned non-flat parts. However, since a wide
variety of the shapes and dimentions of these non-flat
parts are in a building construction site and, also, since
the dimentions of the particular parts vary widely from
site to site, it is not easy to adhere the previously
formed or shaped flashing materials onto substrates,
without causing water leakage problems.
Accordingly, the objects of the present invention
are to obviate the aforementioned problems associated with .
the conventional flashing sheets and to provide an improved
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flashing sheet which is capable of being easily applied to
a substrate or non-flat part of any three dimentional
shape by simply deforming the flashing seet to a form that
completely fits the shape of the substate.
Other objects and advantages of the present invention
will be apparent from the following description.
In accordance with the present invention, there is
provided a flashing sheet which is easily expandable or
stretchable in all directions comprising:
(i) a base sheet consisting essentially of knitted
fabrics made of, as a principal constituent, synthetic
fibers and having a high expandability or stretchability
in all directions, and;
(ii) at least one moaified bitumen layer laminated
on at least one surface of the base sheet, said modified
bitumen layer containing a mixture of bitumen and rubber.
The present invention will now be illustrated in
detail with reference to the accompanying drawings illustrat-
ing the preferred embodiments of the present invention,
but is not intended to be limited to these embodiments.
Fig. 3 through 8 are cross-sectional views illustrat-
ing the structures of the various embodiments of the
flashing sheets according to the present invention.
As illustrated in Fig. 3, the basic structure of
the flashing sheet according to the present invention
comprises a base sheet 21 having a modified bitumen layer
22 laminated on one, surface thereof. The base sheet 21,
which is used as the base material of the flashing sheet of
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the present invention, is composed of knitted fabrics made
of, as a principal constituent, sunthetic fibers, such as,
for example, polyamide (e.g. Nylon) fibers or polyester
fibers. These knitted fabrics naturally have a high
expandability in all directions. Preferable knitted
fabrics employed in the flashing sheets of the present
invention are those which have an expandability or stretch-
ability of 100% or more. Such knitted fabrics are well
known to those skilled in the art.
The modified bitumen layer 22 can be composed of a
mixture of bitumen and rubber. The rubber employed in the
preparation of the modified bitumen layer 22 include
vulcanized or unvulcanized rubber or reclaimed rubber, for
example, natural rubber and synthetic rubber, such as
styrene-butadiene rubber, acrylonitrile-butadiene rubber,
chloroprene rubber, butadiene rubber, isoprene rubber,
butyl rubber, ethylene-propylene rubber, ethylene-propylene
diene mar, polyisobutyrene, chlorinated polyethylene and
the like. These rubbers can be used alone or in any
mixture thereof. In addition, the modified bitumen can
contain conventional softeners or tackifiers, for example,
rosin or its derivatives (e.g. estergum), tall oil, cumarone-
-indene resin, various petroleum resins or polyolefins
(e.g. polybutene), various process oils, etc.
The modified bitumen layer 22 is denatured to
impart thereto a high flexibility and expandability at
ambient temperature or less by blending the rubber into
the bitumen, while the layer 22 still has a preferable
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waterproofing function. The mixture of the layer 22
generally contains approximately 5 through 95% by weight
of bitumen and approximately 5 through 95~ by weight of
rubber, and, preferabley contains 20 through 90~ by weight
of bitumen and 10 through 70% by weight of rubber. In the
case where the content of the bitumen is less than approxi-
mately 5% by weight, the affinity of the modified bitumen
to a bituminous waterproofing membrane becomes unpreferably
poor. Contrary to this, if the content of the rubber is
less than approximately 5% by weight, the flexibility and
expandability of the modified bitumen at a low temperature
becomes unpreferably poor. The modified bitumen layer 22
may be one or more layers. In the case where two or more
layers 22 are located, these layers can be composed of the
same or different compositions.
The thickness of the modified bitumen layer 22 used
in the present invention may be varied over a wide range,
but will generally be in the range of from 0.2 to 5 mm
and, more preferably, in the range of from 0.5 to 2 mm.
A flat flashing sheet 20 having a size large enough
to cover a non-flat substrate can be easily and directly
applied to the substrate as mentioned hereinabove. This
is because, since the flashing sheet 20 according to the
present invention is easily expandable in all directions,
the flashing sheet 20 can be manually deformed so as to
fit the shape of the non-flat substrate to be covered.
Thus, the flat flashing sheet 20 having a size large
enough to cover a non-flat substrate can be, without cutting
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or folding, applied to the substrate by means of any
conventional adhesive (e.g. hot bitumen, bitumenous cement)
by only applying a manufal force without causing water
leakage problems. After the application of the flashing
S sheet 20, a conventional bituminous roofing membrane may
be laid over the modified bitumen layer 22 of the flashing
sheet 20.
The flashing sheet of the present invention can be
easily prepared at the factory in a manner as similar to
that used for the manufacture of the conventional bituminous
roofing membranes, except that the above-mentioned base
sheet and modified bitumen are used.
Fig. 4 illustrates another embodiment of the flashing
sheet according to the present invention, in which a
flashing sheet 23 comprises the base sheet 21, the modified
bitumen layer 22 laminated on one surface of the base
sheet 21 and an adhesive layer 24 consisting essentially
of a substantially presssure-sensitive self-adhesive
composition. The adhesive layer 24 is covered with a
release sheet 25, which can be removed from the adhesive
layer 24 by manually peeling it therefrom at ordinary
ambient temperature at, for example, a construction site.
According to this embodiment of the present invention, the
flashing sheet 23 may be applied onto any particular
substrate without using an adhesive.
The substantially pressure-sensitive self-adhesive
composition used for the adhesive layer 24 has a pressure-
-sensitive self-adhesive property at ambient temperature or
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even at about -10 through -20C. Such composition can be
composed of bitumen and rubber and, optionally, additives
selected from mineral oil, resin and animal or vegetable
oil. Said rubber includes vulcanized or unvulcanized
rubber or reclaimed rubber, for example, natural rubber or
synthetic rubber such as styrene-butadiene rubber, acryloni-
trile-butadiene rubber, chloroprene rubber, butadiene
rubber, isoprene rubber, butyl rubber, ethylene-propylene
rubber, ethylene-propylene-diene mar, polyisobutylene,
chlorinated polyethylene and the like. Said mineral oil
includes process oil, polymerized high boiling point high
aromatic oil, paraffin, liquid paraffin, white oil, tar
and the like. Said resin includes natural or synthetic
resin such as, for example, rosin or its derivatives (e.g.
estergum), tall oil, cumaron-indene resin, various petroleum
resins, polyolefin (e.g polybutene) and the like. Said
animal or vegetable oil includes animal or vegetable oils
and animal fats such as, for example, linseed oil, tung
oil, sesame oil, cotton seed oil, soyabean oil, olive oil,
castor oil, fish oil, whale oil, beef tallow and the like.
These additives can be used alone or any combination
thereof. For optimum result, it is preferred that said
composition be essentially composed of 5-95% by weight of
; the bitumen, 3-80~ by weight of the rubber, 2-60% by
weight of the resin and 0-40% by weight of the mineral oil
and/or the animal or vegetable oil. The thickness of the
adhesive layer may be varied over a wide range, but will
generally be in the range of from 0.5 to 2 mm.
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The release sheet 25 can include conventional sheet
materials which are generally and widely used for covering
and protecting pressure-sensitive self-adhesive surfaces,
for example, paper, film and the like coated or impregnated
with synthetic resins having a high releasing property,
such as silicone resin, fluorine-containing resin and the
like. The release sheet 25 is removed from the adhesive
layer 25 before the flashing sheet 23 is used at the
construction site. The release sheet 25 is used for
1~ facilitating the handling of the flashing sheet 23 having
the adhesive layer 24 during the production, the storage
and the transportation. The release sheet 25 can also be
used for protecting or covering the modified bitumen
layer 22 of a flashing sheet 26 illustrated in Fig. 5.
This release sheet 25 is removed from the modified bitumen
layer 22 at a construction site so as to effect a water-tight
adhesion between the flashing sheet and the waterproofing
layer thereon.
As illustrated in Fig. 6, mineral granules or
powder 28, such as coarse sand, fine gravel and the like,
can be deposited on one surface of the modified bitumen
layer 22 of a flashing sheet 27. This layer 28 is laminated
on the surface of the modified bitumen layer 22 for the
purpose of preventing the blocking of the flashing sheet
due to the presence of the modified bitumen layer 22.
In addition, as illustrated in Figs. 7 and 8, in
flashing sheets 29 and 30, according to other embodiments
of the present invention, both surfaces of the base sheet 21
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can be laminated with the same or different modif.ied
bitumen layers 22. In the flashing sheet 30, the release
sheets 25 are placed on the surfaces of the modified
bitumen layers 22.
The flashing sheets 29 and 30 can be, without
cutting or folding, applied onto the non-flat substrates
mentined above by means of any conventional adhesives such
as hot bitumen, bituminous cement and the like.
~specially, in the case where the modified bitumen
layer 22 is substantially composed of a mixture of 5
through 95~ by weight of the bitumen, 3 through 80% by
weight of the rubber, 2 through 60% by weight of the resin
and 0 through 40% by weight of the mineral oil and/or
the animal or vegetable oil, the flashing sheet of the
present invention can be directly applied onto the non-flat
substrates mentioned hereinabove without using any adhesives
at ambient temperature or less (that is, the modified
bitumen layer also acts as an adhesive layer).
Furthermore, the flashing sheet according to the
present invention can comprise (i) a base sheet, (ii) one
or two first modified bitumen layers composed of, for
example, 5 through 95% by weight of bitumen and 5 through
95~ by weight of rubber and, optionally, conventional
softeners and/or tackifiers, (iii~ one or two second
modified bitumen layers having a pressure-sensitive self-
-adhesive property and composed of, for example, 5 through
95~ by weight of bitumen, 3 through 80% by weight of
rubber, 2 through 60% by weight of resin and 0 through 40
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by weight of mineral oil, animal or vegetable oil or any
mixture thereof and (iv) one or two release sheets. Since
this flashing sheet contains the second modified bitumen
layer having a pressure-sensitive self-adhesive property in
addition to the first modified bitumen layer, the flashing
sheet can be easily applied at a construction site by means
of a cold application process ~i.e. without using hot
molten bitumen at a construction site) without decreasing
the strength of the flashing sheet due to the presence
of the relatively tough first modified bitumen layer.
The flashing sheet according to the present invention
is manufactured at a factory, usually in the form of a
roll, and then, applied to the particular substrate, at
the construction site, after cutting the flashing sheet
into a proper size to cover the particular substrate. The
flashing sheet of proper size if adhered to the substrate
with or without using any conventional adhesive in such a
manner that the flashing sheet is manually and freely
deformed so as to fit the three dimentional shape of the
substrate, and that the flashing sheet is in close contact
with the substrate. Generally, a cut line is not provided
in the flashing sheet of the present invention during the
flashing work at the construction site.
According to the present invention, the flashing
seal at the non-flat parts or substrates having solid or
three dimentional shapes such as, for example, the edges
and the corners of roofs and walls of the building, the
areas around roof drains and roof penetrations (e.g. vent
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pipes, skylights) can be effected without causing water
leakage problems.
As mentioned hereinabove, since the present flash-
ing sheet is easily expandable in all directions due to
the facts that the flashing sheet comprises knitted fabrics
having a high expandability in all directions, and a
modified bitumen layer having a high flexibility and
expandability, and also, since the modified bitumen layer
has a preferable waterproofing property, the present
flashing sheet can be simply and directly applied onto the
non-flat three dimentional parts of the substrate without
causing water leakage problems. Furthermore, the present
flashing sheet can be conveniently applied onto the
non-flat parts of the substrate without cutting and folding
the flashing sheet. Even if the flashing sheet of the
present invention is deformed at the construction site, so
as to fit a particular three dimentional complex shape of
a substrate, the deformation of the flashing sheet is not
locally concentrated, but occurs uniformly, due to the
facts that the modulus of stretch of the flashing sheet is
low when the sheet is deformed and, also, that the knitted
fabrics are used as a base sheet. Synthetic fibers of
which the knitted fabrics are made have a high streching
modulus and low elongation. However, once synthetic
fibers are knitted, the resultant knitted fabrics have a
high expandability and stretchability due to their knitted
structure. In addition, since the flashing sheet of
the present invention has the base sheet and has a high
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deformability over a wide temperature range including a
low temperature such as -40C, the present flashing sheet,
after the application on site, can advantageously withstand
the movement of the substrate based on external conditions
such as temperature, time and load applied to the substrate.
Thus, the flashing sheet of the present invention has both
an excellent application workability and a high flashing
seal ability.
