Note: Descriptions are shown in the official language in which they were submitted.
CA 02239213 1998-06-01
W O 97/20780 PCT~EP96/05300
MAN-MADE VITREOUS FIBRE PRODUcTS AND THEIR USE
IN FIRE PROTECTION SYSTEMS
This invention relates to man-made vitreous fibre
(MMVF) products which are constructed to be useful for fire
protection.
Many fire protection products depend, at least in
part, on the endothermic properties of a component in the
product to provide fire protection. For instance gypsum is
a calcium ~ulphate hydrate. If a high temperature ~lame is
applied to one surface of a gypsum board, the he~ted gypsum
decomposes with absorption of heat and liberates water.
Accordingly, a fire front will gradually transfer through
the thickness of the board, with the temperature on the
side distant from the flame being maintained at 100~C or
less.
Since the effectiveness of a product made using an
endothermic material is proportional, inter alia, to the
amount of the endothermic material, it is desirable for the
product to have a high concentration of the endothermic
material. For instance a gypsum board generally consists
almost entirely of gypsum. Unfortunately such materials
are physically very weak.
It is proposed in CH 382060 to include some
endothermic materials in an MMVF product. A product is
mentioned which allegedly contains 25 to 30 % by weight
glass fibres and 70 to 75 % by weight Kieselguhr bonded
into the fibres by a phenolic binder. Apparently it is
made by introducing Kieselguhr into a preformed web.
It is difficult to introduce inorganic particulate
material into a preformed MMVF product in a satisfactory
manner. For instance, if the inorganic additive is
sufficiently finely ground it may be possible to inject the
powder into the web but it will then dust out of the web
again. It is also possible to impregnate the web with an
aqueous slurry of the finely ground powder, but the web
then has to be dried and this is uneconomic.
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So far as we are aware, the products described in CH
382060 have not been commercialised successfully. This is
probably due, in part, to the fact that the endothermic
material was always very finely ground so as to allow its
introduction into the preformed web, and was not adequately
bonded into the web.
Many of the bonding agents which are conveniently used
for MMVF products require being heated to a high
temperature, for instance 200~C or higher, in order to cure
them. Endothermic materials which have an endothermic
decomposition temperature well below 200~C (such as
Kieselguhr) are therefore likely to undergo decomposition
during curing.
It would be desirable to be able to combine the known
properties of an air laid web of MMV fibres with the fire
protection properties of endothermic materials without
incurring the manufacturing difficulties and the other
disadvantages of known products, such as described in CH
382060.
A fire protection material according to the invention
comprises an air laid web of MMVF fibres through which is
substantially uniformly distributed a particulate
endothermic material, wherein the endothermic material has
a particle size above 5 ~m and is bonded to the MMV fibres
of the web and is a material which is a carbonate or a
hydrate and the particles are heat stable at up to 200~C
and decompose endothermically at a temperature above 200~C.
The particulate endothermic material must be heat
stable at temperatures up to 200~C. That is, it must not
undergo substantial endothermic decomposition a~
temperatures of 200~C or less, preferably 240~C or less.
Heat stability at temperatures up to 200~C may be obtained
in various ways. For instance the material chosen may be
such that it undergoes no endothermic decomposition at
temperatures below 200~C. In this way it can be subjected
to high temperatures but retain its ability to decompose
endothermically when the fire protection product is in use.
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AlternatiVely particulate materials may be used wherein the
particles tend to begin endothermic decomposition below
200~C but which are provided in such a form that they do
not undergo substantial decomposition at temperatures up to
200~C. In this way they also retain their ability to
decompose endothermically when the fire protection product
is in use. Such materials may undergo small amounts of
decomposition at temperatures of up to 2000c, but they do
not undergo substantial decomposition and thus are heat
stable.
Preferred materials liberate carbon dioxide and/or
water of crystallisation only at temperatures above 200~C.
Suitable materials are magnesium hydroxide, calcite
(calcium carbonate), dolomite, siderite, aragonite,
magnesite, brucite, magnesium carbonate, barium carbonate,
barium hydroxide, ferric hydroxide, ferrous hydroxide,
pyrite, and silicon compounds with water of crystallisation
which do not liberate any water at temperatures up to
200~C.
The particle size of the endothermic material must be
above 5 ~m. Accordingly normally 90% by weight of the
particles are above 5 ~m. Preferably the particle size is
at least 90 % above 10 ~m, more preferably at least ~0~
above 15~m. ~or materials which undergo no decomposition
below 200~C, it can be at least 90 % below 200 ~m, for
instance at least 90 % below 100 ~m. Expressed as mean
particle sizes, the preferred ranges are 5 or 10 to lOO~m,
preferably 10 to 70~m, most preferably 15 to 50~m. A mean
particle size of around 15 to 50 ~m, often around 35 ~m, is
often satisfactory.
Alternative materials are those which tend to liberate
carbon dioxide and/or (in particular) water of
crystallisation at temperatures below 200OC, but which are
provided in a form such that liberation of carbon dioxide
and/or water is minimised. For instance, materials which
hav~ a temperature of decomposition of between 150~C and
200~C, for instance from 180 to zOo~C, may be provided in
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the form of especially coarse particles. We find
surprisingly that materials of this type in the form of
coarse particles can withstand temperatures up to 200~C,
and o~ten up to 240~C, without substantial decomposition by
S release of water of crystallisation and/or carbon dioxide.
Preferred materials of this type are those which liberate
water of crystallisation, for instance aluminium hydroxide,
which if used in the form of fine grains loses all its
water of crystallisation at around 185~C.
For these materials suitable mean particle sizes are
at leas~ 100~m, often at least 500~m, and even up to 3mm,
such as from 0.5 to 1.5mm.
Materials which liberate carbon dioxide at
temperatures below 200~C when in fine-grain form can also
be provided in coarse-grain form to render them heat stable
at temperatures up to 200~c in the same way as for
materials which release water o~ crystallisation.
One preferred class of materials is the class of those
which liberate carbon dioxide, such as calcium carbonate,
and especially such materials which liberate carbon dioxide
at temperatures above 400~C and preferably above 600~C.
For instance calcium carbonate liberates carbon dioxide
endothermically at temperatures in the range 700 to 1000~C.
Another class of materials is the class of crystalline
materials which liberate water of hydration at temperatures
of above 200~C, preferably above 240~C, for instance 270 to
370~C or higher.
Materials, or mixtures of materials, which have
dif~erent endothermic reactions at two or more temperatures
are very desirable since it spreads fire resistance over a
large scale. For instance a mixture of hydrate and
carbonate is desirable for this reason.
It is desirable that the material, or each material in
the mixture, should have as high an endothermic energy as
possible. Some materials which might have a high
endothermic energy are excluded because they decompose
completely at below 200~C. A particularly preferred
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material is magnesium hydroxide since it ha high
endothermic energy and is stable at 200~C and is
conveniently available in coarse particle size.
~ The particle size of the endothermic material should
preferably be as coarse as is reasonably possible so as to
allow good bonding of the endothermic material into the web
without need for the use of a large amount of bonding
agent. For instance the surface area of 1 gram of a 1 ~m
filler typically is around 50 times the surface area of 1
gr~m of a 50 ~m filler. Thus a 50 ~m filler requires very
much less binder, for satisfactory binding propertieS, than
a 1 ~m filler. In the invention, by using relatively
coarse endothermic particulate material, it is possible to
maintain good bonding using an amount of binder which is
no~ unacceptably more than the amount which would be used
in the absence of the endothermic material. For instance
the dry weight of binder is typically in the range 1 to 3
% in the conventional MMVF product and in the invention
good bonding can be achieved when the amount of binder is
about the same or not more than 50 to lOo % more, for
instance within the range 2 to 6 % by weight of the
product.
The invention is particularly useful when the
particulate material is abrasive, but it can be used for
softer, less abrasive particulate materials.
It is necessary that the MMVF product should be bonded
into the web in order that there is little or no dusting of
the product from the web during transport and handling.
Very small amounts of dusting are acceptable since the
product can be covered on each surface by a fire resistant
and temperature stable covering such as aluminium foil or
other coating, but excessive dusting is unacceptable. A
suitable test for determining whether or not it is
satisfactorily bonded is that described by Schneider et al,
Ann. OccuP. HYq., Vol. 37, No. 6, pp 631--644,1993.
The binder which is used for bonding the endothermic
material into the MMVF product can be any of the binders
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conventionally used for bonding MMVF products. The amount
of binder is generally in the range 2 to 6 % by weight of
the product.
The web of MMVF fibres must be an air laid web as it
is impracticable to wet lay it and then to dry it. As is
well known, an air laid MMVF web has (even after
compression) a much lower density than a wet laid product.
For instance the air laid web (excluding the endothermic
material, which also acts as a filler) will always have a
density below 300kg/m , often below 250 kg/m . Impregnating
a preformed fibre web with the endothermic material will
give a non-uniform or otherwise unsatisfactory product,
with more endothermic material adjacent the side of entry
than elsewhere. Impregnation with an aqueous slurry is
wasteful of ener~y because of the need to dry the material.
The air laid web may be formed by applying mineral
melt to a rotating fiberising rotor thereby throwing the
melt from the periphery as fibres and forming a
substantially annular cloud of the fibres, spraying binder
into the annular cloud of fibres, carrying the fibres
axially from the rotor towards a collector surface, mixing
the endothermic material with the fibres and collecting the
mixture of fibres and endothermic material on the
collecting surface as a web. This web may be the web of
2~ the final fire resistant product or, more usually, the
initial web is laminated upon itself and is then compressed
to form a batt, and it may be this compressed batt which is
used as the web in the fire resistant product of the
invention.
In order that the coarse, particulate, endothermic
material is bonded into the web, it is preferred that the
particulate material is coated with binder before it is
mixed with the MMVF fibres. A preferred way of making the
product of the invention comprises forming the annular
cloud of MMVF fibres as described above, coating the
endothermic particulate material with binder and mixing the
coated particulate material into the cloud, and collecting
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W O 97/20780 PCT~EP9~/05300
the resultant mixture on a collector ~urface as a web.
Additional binder is usually sprayed into the cloud to
increase fibre-fibre bonding.
A preferred way of coating the particulate endothermic
material with binder is to form a slurry of the particulate
material in a~ueous binder, in which event the particulate
material can then be introduced into the annular cloud by
spraying. In practice, the slurry will normally contain at
least 5 %, by weight of the slurry, of the particulate
lo endothermic material but the amount is often above 10 % or
even 20 %. It can be as much as 60 % but is usually not
more than about 40 ~.
It is desirable for the specific gravity of the slurry
to be high since this increases the penetration of the
slurry into the annular cloud. The specific gravity can be
at least 1.0 and is usually at least 1.1, preferably at
least 1.2 and usually at least 1.3 and often at least 1.4.
It is usually below 2, generally below 1.7. In order to
facilitate spraying, it is desirable that the slurry should
be reasonably stable against settlement and the aqueous
binder therefore preferably includes a dispersion
stabiliser that will inhibit settling. The dispersion
stabiliser may be any suitable viscosifier, but preferably
it is a colloidal material since the presence of colloidal
material in the aqueous phase can both inhibit settlement
of the filler and ad~ust the rheology of the slurry so as
to facilitate spraying.
Prefera~ly the dispersion stabiliser is a clay and
thus the slurry is preferably a slurry of particulate
endothermic material having a size above S ~m, often above
10 ~m and preferably above 30~m in an a~ueous dispersion of
clay particles typically having a size below 5 ~m often
below 3 ~m. The amount of clay or other colloidal material
in the slurry is typically in the range 0.5 to 10% based on
the weight of slurry, often up to 7~, generally 1.5 to 5 %.
The amount of clay, if used, in the air laid product is
generally in the range 0.5 to 3 %. The clay can tend to
J CA 02239213 1998-06-01
have a binding effect and thus may serve not only as a
dispersion stabiliser but also as part or all of the
binder. Preferably, however, organic resin binder is also
used.
A suitable method for spraying such a slurry into the
annular cloud so as to form a bonded air laid web is
described in our International Publication No. W097/20781.
Suitable apparatus for use in this method is described in
our International Publication No. W097/20779.
In another aspect of the invention, a fire protection
product comprises a bonded web of MMV fibres in which is
distributed an endothermic material selected from magnesium
hydroxide and carbonates that do not undergo endothermic
decomposition at up to 200~C and decompose endothermically
at above 200~C. Preferably the web contains magnesium
hydroxide in an amount of at least 5~, more preferably at
least 10% by weight of the total material. The endothermic
material may be introduced in any convenient size and
method and may or may not be distributed uniformly and may
or may not be bonded. Preferably it is distributed
uniformly and is bonded and is in the form of particles of
size above 5 ~m, often above lO~m.
In all aspects of the invention, the amount of
endothermic material is usually in the range 5 to 50%, e.g.
25 to 30%.
The fire resistant products of the invention can be in
the form of slabs, mats, pipes or granulate. When in the
form of slabs they may be provided in the form of a
laminate between steel sheets. Products of this type are
particularly suitable for use as fire doors. The fibrous
products can have a density in the range of 10 to 300
kg/m3.
The mineral fibres of the product can be made from
glass, rock, stone, or slag but preferably they are made
ED St~ET
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PCT~P96/05300
W O 97/20780
from rock, stone or slag because of the extreme fire
resistance of these fibres.
The spinner can be of the s pinning cup type described
in EP 530843 or of the Downey type as described in US
2944284 and US 3343933, but preferably tha rotor is mounted
about a substantially horizontal axis and has a solid
periphery and is constructed to receive melt applied onto
the periphery and to throw mineral fibres off the
periphery. Most preferably it is a cascade spinner
containing 2, 3 or 4 such rotors. A suitable cascade
spinner is described in, for instance, W092/06047. When
the endothermic particulate material is being applied by
spraying a slurry, the slurry may be sprayed coaxially
from, for instance, the last fiberising rotor and/or the
penultimate fiberising rotor and if desired binder may be
sprayed coaxially from the other fiberising rotors.
Accordingly the annular cloud of fibres into which the
slurry is laid will not be a true annulus but will instead
merely extend forward fro~ the outermost parts of the
cascade.
The following is an example of the invention. In this
example, a spinner is used as illustrated in the
accompanying drawings in which
Figure 1 shows a cross-section through a rotor which
forms part of the spinner.
Figure 2 shows a front view of a further rotor
according to the invention showing an alternative liquid
flow outlet.
Figure 1 shows a solid rotor 1 of the type used in a
cascade spinner mounted on a rotatable shaft 3. Fixed to
the rotor is a liquid distribution means 16 having a
distribution surface 11. The substantially frustoconical
surface 11 is a concave surface containing a plurality of
grooves 18, of which six are illustrated. The distribution
surface has a short edge 12 and a long edge 14, the long
edge 14 being forward of the short edge 12. The long edge
14 is at a radius 0.6 R, where R is the radius of the
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rotor. The rotor 1 is supported, on the rotating shaft 3,
by roller bearings 32. The non-rotatable liquid flow duct
S is supported on bearings 30, usually roller bearings,
between the rotating shaft 3 and the non-rotatable liquid
flow duct 5. The non-rotatable liquid flow duct 5 leads
into and is fixed to the liquid flow outlet 7, which is
also non-rotatable. This has two (or more) radially
extending discharge orifices. The radially extending
discharge orifices may be inclined rearwardly at an angle
of 10-45~ so as to ensure discharged liquid meets the
distribution surface at the smallest possible radius.
In use a suspension of particulate solids in an
aqueous phase is supplied (supply means not shown) to the
liquid flow duct 5 which extends through the rotatable
shaft 3, and into the liquid flow outlet 7. The suspension
then passes through the orifices 9.
The partially atomised suspension passes across an air
gap in the direction of the arrows and onto the
distribution surface 11. The rapid spinning of the liquid
distribution means 16 induces radial outward movement of
the suspension, guided by the grooves 18, to the end points
2 0 of the grooves at the edge 14. From these end points
the suspension is flung in atomised form from the
distri~ution surface radially outwards and forward of the
rotor.
If any suspension fails to travel radially outwards
along the grooves 18, but tends to leak back into the
apparatus, it passes along the inlet channel 28 into the
rotating annular chamber 24. Rotation of the chamber
induces the suspension to move to the outer wall o~ the
Ch~ h~-~, from where it flows along outlet channel 26 onto
the distribution surface at its short edge. A seal 34 is
positioned between the chamber 24 and the roller bearings
30. Leakage into other regions of the apparatus is thus
avoided.
Concurrently, melt is applied to the periphery 22 of
the rotor 1 which is spinning rapidly and flinging the melt
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W ~ 97/20780 PCTrEP96/05300
11
from the periphery as fibres. The fibres are blown forward
~y conven~ional air supply means (not shown) in an annular
cloud. As the fibres are blown forward they are met by the
- atomised suspension from the li~uid distribution means.
The suspension and additives it contains penetrate the
annular cloud and coat the fibres.
The fibres are then collected as a web cont~ini ng
uniformly distributed additive on a collector in
conventional manner. The web may be subjected to cross-
lo lapping to form a batt, and the product may ~e compressedand heat cured in conventional manner.
Figure 2 shows an alternative construction for the
liquid flow outlet 7. In this construction it is in the
form of a slot covering around 135~ of the possible 360~.
Liquid additive exits the liquid flow duct S through the
slot 36 and is passed to the liquid distribution surface
11. The liquid additive flows over the region 38. The
"spiral" type path of the liquid arises as a result of the
rapid rotation of the distribution surface in a clockwise
direction. In other embodiments rotation can be in an
anticlockwise direction. The liquid additive is thus flung
from the long edge 14 of the distribution surface in a
substantially upward direction over around 135~ of the
circumference of the distribution surface.
~xamPle 1
A suspension of resol formaldehyde binder in water is
placed in a pulper. A slurry having specific gravity above
1.1 is produced by mixing with the binder dispersion
particulate magnesium hydroxide having a mean size of 35~m.
The slurry is included in fibres at the point of fibre
formation by means o~ the apparatus and process of Figure
1 described above. A slab product is produced from the
resulting fibres.
The same process is carried out without the use of
magnesium hydroxide fire retardant material.
Both the fire resistant slab according to the
invention (slab A) and the conventional slab (slab B) were
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12
subjected to a standard fire test according to IS0 834.
Results are shown in Table 1 below. These illustrate the
temperature on the cold side of the slab after a certain
time.
The results shown indicate the gradual increase in
temperature on the cold side of the slab as a result of
heat passing through the slab. In some products a very
rapid increase in temperature followed by a very rapid
decrease in temperature can be observed. This is due to
combustion of binder. This combustion is minimised in slab
A of the invention.
As can be seen from the results below the time for the
temperature on the cold side of the slab to rise to 190~C
or greater is more than three times as long with slab A
than with slab B, showing the improved fire and heat
resistance of the products of the invention. Poor results
are also obtained when magnesium hydroxide is used having
an average particle size of 2 ~m.
CA 022392l3 l998-06-Ol
wo 97120780 PCTIEP96/05300
13
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