Note: Descriptions are shown in the official language in which they were submitted.
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WO 93/16874 PC'1'1D1C93100064
1 ~~
PROCESS FOR PREPARING A MINERAE FIBRE~ELEMENT COMPRISING A SURFACE
COATING AND APPARATUS FOR CARRYING OUT THE PROCESS.
The present invention relates to a method of producing a mineral
fibre element comprising a mineral fibre base layer having a surface
coating in the form of a fibrous netting formed of a thermoplastic
polymer material, wherein such a surface coating is provided on at
least a part of the surface of the base layer.
Mineral fibre material is used i.a. for thermal and acoustic
insulation in a number of connections.
In order to increase the tactility of the mineral fibre material
used during the handling and mounting thereof it may be coated with
a surface layer, e.g consisting of a non-woven sheet material of
polymer fibres.
Furthermore, such a surface coating serves to reduce or eliminate
the release of fibre wads or single fibres from the mineral fibre
material to the surroundings before, during or after mounting.
Furthermore, a surface coating of the above mentioned type imparts a
considerably increased tensile strength to the mineral fibre
element.
It is known to produce mineral fibre elements of the type mentioned
in the introductory part by adhering a pre-manufactured, non-woven
web material consisting of polymer fibres to the surface of a
web-formed mineral fibre material by using a resin, such as phenol
formaldehyde resin, as an adhesive and by subsequently cutting the
coated mineral fibre web so as to form individual mineral fibre
matts.
Non-woven polymer fibre materials can be produced from thermoplastic
polymers which i.a. are characteristic in being adhesive in melted
state. In the production of non-woven fibre materials the adhesive
effect can be used to bond the individual fibres together to form a
coherent layer.
WO 93/16874 s~ ~"~ PCT/DK93/00064
N~ 4 ~ ~ 2
However, the prior art method suffers from several drawbacks.
In order to impart sufficient strength to the non-woven material so
as to enable it to resist strains during the handling thereof and in
particular during the application of the material onto the uneven
surface of the mineral fibre material, the material used should have
a surface weight of at least about 20 g/m2.
However, it is not necessary to use a surface coating having a
surface weight of such a magnitude in order to obtain a functional
coating, and hence the prior art method involves a certain waste of
material.
Furthermore, the resin used for adhering the non-woven material
implies an increase in the thermal value of the surface coated
mineral fibre element, which is undesirable far fire safety reasons.
In addition, mineral fibre elements produced by the prior art method
are relatively costly, which is partly due to the fact that
non-woven polymer fibre materials are costly and partly that the
method comprises at least two relatively difficult technical process
steps, viz. 1) an even application of the adhesive onto the surface
of the base layer and 2) mounting and pressing of the coating onto
said surface.
Finally, it is strenuous and difficult to form a surface coating
covering the entire surface of the base layer, i.e. both the upper
side and lower side of the base layer and its edge surfaces, by use
of the prior art method.
The object of the present invention is to provide a method of the
type , menti oned i n the i ntroductory part, whi ch i s si mpl er than the
prior art method and by which a mineral fibre element having ~ :
improved properties can be obtained.
,
The method accordi ng to the i nventi on i s character] zed i n that the
surface coating is formed dii~ectly on the surface of the base layer
and that the surface coating is formed by heating a thermoplastic
polymer material so as to melt it and distributing the polymer melt
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CA 02129737 2003-02-13
2290:3-659
3
obtained in i~he form o~ fibres and/or filaments on the
surf<~ce of the base la,~rer ane ccaoling it to form a solid
laye~. .
According to one aspect of the present invention,
there is provided a me t::h.od of producing a miner,~l fibre
element for use as insu:Lation comprising a mineral fibre
base layer having a surface coating in the form of an
irregular pat:t:ern of fibrous thermoplastic polymer material,
wherein such a surface coating .s provided ors air least a
1c) part of the surface of: the base layer, wherein the surface
coating is formed directly on the surface of the base layer
and that the surface coating i.s farmed by heating a
thermoplastic polymer material so as to melt the polymer
material and distributing the polymer melt obtained in a
form of fibres and/or fi.l.aments or; the surface of the base
layer and cooling the polymer melt to form a solid layer.
According to another aspect of the present
invention, there is provided an apparatus for carrying out
the method as described herein, comprisinct one cr more
units, each unit comprising means for melting the
therm~aplastic polymer rnat:eriaL, a number of nozzles, means
for extruding the polymer melt obtained through the nozzles
and d.istribut.ing the extruded polymer material on the
surface of thc= mineral fibre base ~ayer, and means for
direci~ing one or more high pressure gas streams closely past
the nozzles in order tca e:Lor..ga.te the extruded polymer
material so as to form thin filaments and/or fibres.
According to .:till anot,~her aspect of t:he present
invent: ion, there is prot~ided an apparatus as des~~ribed
herein, further compris_i.ng means fc.>r supporting ;end
optionally conveying the base layer.
CA 02129737 2003-02-13
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3a
According to yet another aspect of the present
invention, there is provided ar.. apparatus as described
herein, comprising a suction devir_e.
According to a further aspect of the present
invention, there is p:r,ov~.ide~d an apparatus as described
herein, comprising an c:~blor_g disp~.msirug chamber which via a
pump is in liquid communication with the melting means and
which, at the dispensing chamber's distal end, ~~omprises a
number of closely spaced nozzles, two chambers .Located along
two ride walls of the dispensing chamber and at the distal
end of which a longitudinal slo:: ~.s formed, and means for
directing a high pressure gas sv~ream through th.e said side
wall chambers and out through the slots.
According to yet a further aspect of t:he present
invention, there is provide~~ an apparatus as de~~cribed
herein, optionally comprising mE.ar.~s fo:r mixing a gas into
the polymer melt and a number of pressure guns having
mouths, each pressure e~un compr:i.sing a nozzle, a.nd which via
a pump are in liquid commun~.cation with the melting means,
and means for directing one or more high pressure gas
streams past each of the mouths of the pressure guns.
According to still. a further aspect of the present
invention, there is prc:wrideca an apparatus as described
herein, wherein the pressure guns can be disposed and/or
moved in such a manner that polymer. material is emitted by
the guns and distributer_L over the enti.i:we surface of the base
layer.
According to another aspect of the present
invention, there :is provided an apparatus as described
herein, comprising a suction dev-.~ce comprising an oblong
dispensing chamber having a leng~h greater then the
dimen~;ion of t:he base layer in tue direction extending
CA 02129737 2003-02-13
22903-659
3b
parallel with the said chamber which via a pump is in liquid
communication with the melting means and which, at the
dispensing chamber's distal end, comprises a numr~er of
closely spaced nozzles, two ~~hamY~>ers located along two side
walls of the dispensing chamber and at the distal. end of
which, a longitudinal slot i;s .for_med, and means f_or
directing a high pressure gars strweam through the said side
wall chambers and out throug'.z thE_ slots.
The invention is based on the discovery that by
1.0 forming the polymer layer direct.-y on the surfacE: of the
mineral fibre material the adhes-wve effect posse:~sed by
thermoplastic polymer materials ~n a melted or partly melted
state can be utilized tc~ obtain a highly effective adhesion
between the mineral fibre layer and the surface coating and
1.5 at the same time the use ef ;~ fm:~ther binder can be avoided,
thereby allowing the thermal value of the mineral. fibre
element to be reduced.
Furthermore, the invention is based on the
discovery that the non--woven mate rial used in the prior art
20 method., in particular as a results of the strength
requirements demanded for effect_ng the application of the
said material onto a mineral fibre base layer, h~~s
properties which are undesired, unnecessary and unexpedient
as far' as its function as a surf<rce coating is concerned,
25 and that the direct forzratio:z of the surface coating on the
mineral fibre material provides a possibility of obtaining a
surface coating, the propert.ie;~ of which are exclusively
determined on the basis of the desired functional.
considerations.
30 Thus, the method according to the invention
provides a possibility of fo:rmin~ a surface coating with an
arbitrary surface weight., and as a result it is possible to
CA 02129737 2003-02-13
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3c
obtain a material saving as ;compared to the prior art
method.
Furthermore, by using t:he present methc>d it is
possible to form a surface coai~ing c:ons:isting of fibres
having a smaller thickness than that of the fibres of the
non-woven materials used in t:he prior art method, and thus a
material saving can be obtained as well as a pos~;ibility of
increasing the number of fibres per area unit an~~ hence the
filtration capacity of the surface coating.
Finally, the .invent: ion is based on the discovery
that a surface coated m.inera~~ fibre element can ~~e produced
more economically and easily by forming the su:rfa.ce coating
directly on the mineral fibrE7 rnat.erial than by adhering a
pre-manufactured non-woven material onto
WO 93/1687 ~ ~,~ ' J°~r: PCT/DK93/00064
~~~tw ~a ~'. 4 ,
the mineral fibre material, as the former method does not require a
separate process equipment for producing a non-woven material, and
hence the process steps associated therewith can be avoided, and as
the former method only requires one process step, whereas the latter ,
method requires at least two process steps.
In addition, the surface coating formed by the present method is cut
more easily than the prior art surface coating, which to a large
extent facilitates the cutting of the mineral fibre elements, which
ordinarily is necessary in connect ion with the mounting thereof.
As used in the present invention the term °'mineral fibres"
includes
rock fibres, glass fibres and slag fibres.
As used in the present invention the term "thermoplastic polymer
material" means any natural or synthetic thermoplastic polymer or
polymer blend. A thermoplastic material is characterized in that it
's solid or partially solid at room temperature or at temperature of
use, that it melts when heated and that it solidifies or resumes a
solid or partially solid form when cooled.
The term "thermoplastic polymer material" also includes such
materials which are ordinarily referred to as "thermoplastic hot
melt adhesives" or "hot melt adhesives'° or simply "hot melts".
By way of examples thermoplastic polymer materials are polymers of
ethylenically unsaturated monomers, such as polyethylene,
polypropylene, polybutylenes, polystyrenes, poly(a-methyl styrene),
polyvinyl chloride, polyvinyl acetate, polymethyl methacrylate,
polyethyl acrylate, polyacrylonitrile, etc; copolymers of
ethylenically unsaturated monomers, such as copolymers of ethylene
and propylene, ethylene and styrene, polyvinyl acetate, styrene and
malefic anhydride, styrene and methyl methacrylate, styrene and ethyl
acrylate, styrene and acrylonitrile, methyl methacrylate and ethyl
acrylate etc; polymers and copolymers of conjugated dienes, such as °
polybutadiene, polyisoprene and polychloroprene and polymers of bi-
polyfunctional monomers, such as polyesters, polycarbonates,
polyamides and polyepoxides.
WO 93/16874 ~ ~ ~ ~ o ~ a' PC'T/DK93/00064
Particularly preferred thermoplastic polymer materials are
polyesters, polyamides, polypropylene and polyvinyl acetate.
By using the method according to the invention it is possible, as
mentioned above, to produce mineral fibre elements having a surface
coating of an arbitrary thickness.
However, in order to obtain a suitable tactility of the finished
product it is preferred that the surface coating has a surface
weight of from 2 g/m2 to 50 g/m2, preferably from 5 g/m2 to 20 g/m2
and most preferably from 10 g/mz to 15 g/m2.
The base layer may have any form and typically it has the form of an
endless web, a web, a mat or a sheet.
Mats and sheets may be formed by cutting.
Furthermore, the present invention relates to an apparatus for
carrying out the method of the invention, which apparatus is
characterized in that it comprises one or more units, each unit
comprising means for melting a thermoplastic polymer material, a
number of nozzles, means for extruding the polymer melt obtained
through the nozzles and distributing the extruded polymer material
on the surface of a mineral fibre base layer, and means for
directing one or more high pressure gas streams close.iy past the
nozzles in order to elongate the extruded polymer material so as to
form thin filaments and/or fibres.
The melting means may have the form of an extruder or a melting
chamber which e.g. can be heated by means of electric heating
elements:
A preferred embodiment of the apparatus according to the invention
is characterized in that it comprises an oblong dispensing chamber
which via a pump is in liquid communication with the melting means
and which at its distal end comprises a number of closely spaced
nozzles, two chambers located along the two side walls of the
dispensing chamber and at the distal end of which a longitudinal
slot is formed, and means for directing a high pressure gas stream
WO 93/16874 ~y~ z ~ 'V~~~ PCT/DiC93/00064
~,a ~~-' ~ '~ 6 .
through- the said side wall chambers and out through the slats.
An apparatus of the above mentioned type is ordinarily referred to
as a "melt blow apparatus".
'
Another preferred embodiment of the apparatus according to the
invention is characterized in that it optionally comprises means for
mixing a gas into the polymer melt and that it comprises a number of
pressure guns, each comprising a nozzle, and which via a pump are in
liquid communication with the melting means, and means for directing
one or more high pressure gas streams past each of the mouths of the
pressure guns.
An apparatus of the above mentioned type is ordinarily referred to
as a "hot melt spray apparatus".
Optionally, the apparatus according to the invention comprises means
for supporting and optionally conveying the base layer.
Such support means may e.g. have the form of any suitable transport
means, such as roller belt, roller path, conveyor belt or conveyor
path.
The apparatus according to the invention may be disposed between two
such transport means or vis-a-vis an opening formed in such a
transport means.
In the apparatus according to the invention the nozzles are
preferably equally spaced.
When using the apparatus according to the invention it is preferably
located above a mineral fibre base layer conveyed continuously in a
distance therefrom.
The apparatus according to the invention is preferably located in
such a manner that the nozzles extend over the entire dimension of
the base layer in a direction perpendicularly to the direction of
advance of the transport means.
WO 93/16874
. . '~' y '~' ~ ~ ~ 4~? PCT/DK93/00064
The apparatus according to the invention preferably comprises a
suction device, such as a suction box, located below the base layer
and vis-a-vis the nozzles and which serves to remove the gas used
for elongation of the polymer material extruded through the nozzles.
When it is desired to coat both the upper side and the lower side of
a base layer conveyed on a transport means, this can be achieved by
using two apparatuses according to the invention, said apparatuses
being located above and below, respectively, the base layer and
displaced in relation to each other and each apparatus having a
cooperating suction device located on the opposite side of the base
layer.
Alternatively, two apparatus located displaceably in relation to
each other on the same side of the base layer can be.,used, in which
case a turning of the base layer between the two apparatuses is
effected.
A melt spray apparatus, vide the above definition thereof, is
suitable for use without a cooperating suction device.
Thus, in the coating of both the upper side and the lower side of a
base layer conveyed on a transport means by use of a melt spray
apparatus the desired coating can be obtained by using two such
apparatuses located above and below, respectively, the base layer
and vis-a-vis each other or by using such an apparatus in which the
nozzles are disposed both above and below the base layer.
A particularly preferred embodiment of the melt spray apparatus
defined above is characterized in that one or more units together
comprise a number of pressure guns which can be disposed and/or
moved in such a manner that the polymer material emitted by the guns
can be distributed over the entire surface of the base layer.
The above mentioned
particularly preferred embodiment of the
apparatus according to the invention provides a possibility of
producing a fully coated mineral fibre element.
In the coating of e.g. web, mat or sheet formed base layers it is
WO 93/16874 ' ~ ~ ~Y~ PCT/DK93/00064
......
thus possible to coat in a simple manner both the upper side and the
lower side of the base layer as well as its edge sides.
The above mentioned particularly preferred apparatus preferably
comprises partly pressure guns disposed circumferentially around the
whole of a base layer conveyed on a transport means and which are
equally spaced, and by means of which the upper side and the lower
side of the base layer as well as its side edge surfaces can be
coated, partly one or more pressure guns which are displaceable in
vertical direction or in a vertical plane, and by means of which the
end edge surfaces of the base layer can be coated.
Such displaceable pressure guns are preferably automatically
controllable.
A particularly preferred embodiment of the melt blow apparatus
defined above, wherein the apparatus comprises a suction device, is
characterized in that it comprises a dispensing chamber having a
length greater than the dimension of the base layer in the direction
extending parallel with the said chamber.
By using the above mentioned particularly preferred embodiment of
the apparatus according to the invention in the coating of e.g. web,
mat or sheet formed base 1 avers i t i s poss i bl a to coat i n a s i mpl a
manner both the upper side and the lower side of the base layer as
well as its side edge surfaces, as the polymer material dispensed
outside the width dimension of the base layer can be applied to said
side edge surfaces partly by means of the suction device.
The high pressure gas used for elongation of the polymer material
extruded from the nozzles is preferably atmospheric air.
The high pressure gas used is preferably hot in order to avoid
excessive cooling of the extruded polymer melt before it is
deposited on the surface of the base layer.
The gas can be pressurized by means of e.g. a blower or a
compressor.
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WO 93/16874 PCT/DK93/00064
As mentioned above, the melt spray apparatus according to the
invention can optionally comprise means for mixing a gas into the
polymer melt so as to form a melt/gas mixture.
When such a melt/gas mixture is dispensed from the above mentioned
mel t spray apparatus, the gas wi 11 expand i n the polymer mel t, and
as a result a certain foaming of the dispensed polymer material is
obtained during the cooling of the melt and the subsequent
solidification thereof to form a netting consisting of partially
foamed strings.
By using foamed fibres a surface coating can be obtained, which
covers a greater portion of the surface of the base layer and hence
has an increased tactility and mineral fibre retention capacity
15' compared to a coating consisting of non-foamed fibres and of the
same surface weight.
Alternatively, the above mentioned increased covering capacity can
be utilized to form a coating having a lower surface weight and
hence to reduce the material consumption.
The gas used for admixture with the polymer melt can be nitrogen or
carbondioxide.
The invention will now be described in further details with
reference to the drawings, wherein
Fig. 1 is a perspective view of a preferred embodiment of the
apparatus according to the invention,
Fig. 2 is a sectional view of the lower portion of the dispensing
container of the apparatus of Fig. 1, and
Fig. 3 is a perspective view of another preferred embodiment of the
apparatus according to the invention.
Fig. 1 shows an apparatus 1 comprising an open container 2 for
filling of a thermoplastic polymer material in a solid form, e.g, in
the form of pellets, the lower portion of the container 2 having the
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f'
WO 93/16874
PCT/DK93/00064
,
form of a, hopper 2 debouchi ng i nto a pi pe 4 by means of wh i ch the
container 2 is connected with an extruder 5 wherein a heating of the
polymer material for melting thereof is effected and from which the
polymer melt obtained is extruded.
5
The extrusion of the polymer melt from the extruder 5 is effected by
means of a rotatable screw conveyor located in the interior of the '
extruder 5 and which is driven by a motor (not shown).
10 The polymer melt extruded from the extruder 5 is conveyed via a pipe
6 and by means of a pump (not shown) to an oblong dispensing
container 7 which narrows downwardly, and which in its bottom
comprises a number of closely spaced nozzles disposed in a row,
through which the polymer melt is extruded under the influence of
the pressure generated by the pump.
The two side walls of the dispensing container 7 have the form of
double walls for forming two slot-formed chambers along the outside
of the dispensing container. A slot extending along the row of
nozzles is formed at the lower end of each of the two side wall
chambers.
Via a pipe 10 hot air is blown into the two side wall chambers by a
blower 8 driven by a motor 9 and further out through the two
appertaining slots and hence closely past the nozzles where it
Serves to elongate the polymer strings extruded through the nozzles
and to break up said strings in separate fibres and/or filaments 11.
The dispensing container 7 is located above a mineral fibre web 12
conveyed on a conveyor belt (not shown) transversely to the
direction of advance of the web. The dispensing container 7 has a
length corresponding to the width of the mineral fibre web 12.
The fibres and/or filaments 11 emitted from the dispensing container
are deposited on the surface of the mineral fibre web 12 so as to
form a coherent netting 13. .
Below the mineral fibre web 12 a suction box 14 is located
vis-a-vis the dispensing container 7 and between two conveyor belts
WO 93/16874
P(.'T/DK93/00064
. ~ s !1 .r a~ h!
I 1 ~ .~ ~ .e ,~
(not shown), said suction box removing the air blown out through the
slots in the side wall chambers.
The suction box 14 is connected with a suction pump (not shown) via
a pipe 15.
Fig. 2 shows a cross section of the lower portion of the dispensing
container 7 of the apparatus of Fig. 1. The dispensing container 7
comprises an interior chamber 20 for containing the polymer melt and
two side wall chambers 21 for supplying air.
The interior chamber 20 tapers downwards and in the outermost
portion of the tapered section 22 an opening 23 is formed for the
dispensing of polymer melt.
In the bottom of each of the two side wall chambers 21 a slot 24 is
formed along the outermost portion of the tapered section 22,
through which air is blown out from the side wall chambers 21.
The air blown out through the slots 24 is directed to the tip of the
interior chamber 20 where it is contacted with the dispensed polymer
melt for the elongation and breaking up of the melt.
Fig. 3 shows an apparatus 30 comprising a polymer melting chamber
housing 31 for praducing a polymer melt, which housing 31 via a tube
32 is connected with an oblong melt distribution chamber 33
connected via a number of tubes 34 with a number of vertical
pressure guns disposed in a row along the melt distribution chamber
33 and which comprise a channel formed nozzle.
The housing 31 contains a melting chamber wherein a thermoplastic,
solid polymer material supplied thereto, e.g. in the form- of
pellets, is heated by electric heating elements to melt it and from
which the polymer melt obtained is subsequently pumped through the
tube 32, the distribution chamber 33, the tubes 34 and the pressure
guns 35 by a pump located in the housing 31.
Furthermore, the apparatus 30 comprises means (not shown) for
supplying air to each pressure gun 35.
WO 93/16874 s ~~ '~~ g~ ~~5 ~'GT/DK93/40064
12
The air supplied to the pressure guns-35 is divided in each pressure
gun 35 into a number of elongation streams and a number of
orientation streams.
The elongation streams serve to elongate the polymer material
dispensed from the nozzle and optionally to break it up in
individual fibres and/or filaments 36, whereas the orientation
streams primarily serve to distribute the fibres and/or filaments 36
obtained in the longitudinal direction of the pressure gun row and
optionally also to further elongate and break up the polymer
material.
The pressure guns 35 comprise a number of channels for directing the
elongation streams, said channels debouching close to the nozzle
channel and having a form which impart to the individual partial
streams such a direction that the major portion of the formed
polymer fibres and/or filaments 36 in a distance from the mouth of
the nozzle are distributed in such a manner that the polymer
material forms an approximately circular deposit on a horizontal
stationary base.
Furthermore, the pressure guns 35 comprise a number of channels for
directing the orientation streams, said channels debouching in both
a greater axial and a greater radial distance from the mouth of the
channel formed nozzle than the orientation streams. The channels
have a form which imparts to the partial streams such a direction
that the major portion of the polymer fibres and/or filaments 36 are
distributed in such a manner that the polymer material forms an
oblong approximately oval deposit on a horizontal stationary base.
The row of pressure guns 35 is disposed above a mineral fire web 37
conveyed on a conveyor belt (not shown) transversely to -the
direction of advance of the web. The pressure guns 35 are equally
spaced and extend over the entire width of the mineral fibre web 37.
The fibres and/or filaments 36 dispensed from the pressure guns 35
are deposited on the upper side of the mineral fibre web 37 so as to
form a coherent netting 38.
WO 93/16874 PCT/DK93/00064
. . 6'~ ~:~ .x s3 rJ
13 ~~ ~~ s~~:: ~v
Below the mineral fibre web 37 a suction box 39 is located
vis-a-vis the raw of pressure guns 35 and between two conveyor belts
(not shown), said suction box removing the air blown out from the
pressure guns 35.
The suction box is connected with a suction pump (not shown) via a
pipe 40.
The invention will now be described in further details with
reference to the following examples.
Example 1 '
In a full scale test plant a series of tests were carried out in
which rock fibre webs were coated with fibres of a thermoplastic
polymer material by use of the method according to the invention.
The tests were carried out by use of a melt blow apparatus
comprising a dispensing chamber located above the rock fibre webs
and having a greater length than the width of the rock fibre webs
and a suction box' located below the said webs and vis-a-vis the
dispensing chamber. The distance between the nozzles of the
dispensing chamber and the upper side of the rock fibre webs was
about 0.5 m.
The rock fibre webs contained about l.6fo by weight of a binder in
the form of phenol formaldehyde and had a specific weight of about
kg/m3 and a thickness of about 100 mm. The webs had a surface
temperature of about 20'C.
The polymer starting material used was a polyester in the form of a
granulate marketed under the name EMS 6760.
The polyester was melted in an extruder and subsequently the melt
obtained was extruded through the nozzles in the dispensing chamber
and the extruded polymer strings were elongated by means of two gas
streams and broken up to form separate fibres which were deposited
on the upper surface and the side edge surfaces of the rock fibre
webs.
WO 93/16874 . ~-~~~~~ '~ '-~
PCT/DK33/00064
14
- In the tests a surface coating having a surface weight of partly 10
g/mz and partly 15 g/m2 was formed. The surface coating had the
appearance of a non-woven material.
The coated rock fibre webs
produced had a tactility corresponding
completely to the tactility of the prior art mineral fibre elements
having a surface coating consisting of poiyester.
The polyester fibres applied had an average diameter of about 5 ~cm.
The surface coating having a surface weight of 10 g/m2 had a thermal
value of 0.3 MJ/m2, whereas the coating having a surface weight of
g/m2 had a thermal value of 0.45 MJ/m2. For comparison it should
be noted that a surface coating consisting of a non-woven material
15 of polyester and having a surface weight of 20 g/m2 and an adhesive
layer of phenol formaldehyde resin has a thermal value of 1.0 MJ/m2.
Furthermore, the air permeability of the rock fibre webs produced
was determined and the results showed that no significant difference
in air permeability was observed between the said coated webs and
corresponding webs with no coating.
Furthermore, i n the tests a mi neral fi bre web compri si ng a surface
coating having a surface weight of 15 g/m2 on both sides of the web
was produced.
The tensile strength of this web was determined and as a result it
was found that the tensile strength was 25% higher than the tensile
strength of a corresponding rock fibre web without any surface
coating.
~xamo~?
In a full scale test plant a series of tests were varied out in
which rock fibre webs were coated with fibres of a thermoplastic
polymer material by use of the method according to the invention.
An initial test series was carried out by use of a melt spray
apparatus wherein the pressure guns were located in a row above the
WO 93/16874 PCT/DK93/00064
f
rock fibre webs and spaced 10 cm apart, and each individual pressure
gun laid out a layer of a width of from 10 cm to 15 cm. The distance
between the nozzle mouths of the pressure guns and the upper side of
the mineral fibre webs was of from about 0.3 to about 0.5 m.
Air having a pressure of 4-5 bars and a temperature of 210-230'C was
used as elongation and orientation gas.
The rock fi bre webs contai ned about 1.69 by weight of a bi nder i n
the form of phenol formaldehyde and had a specific weight of about
30 kg/m3 and a thickness of about 100 mm. The webs had a surface
temperature of about 20°C on the application of the surface coating.
A polyester marketed by the company Huls under the name Dynapol S
3g0 was used as polymer material.
The polyester was melted in a melting vessel at a temperature of
about 220'C, and subsequently the melt obtained was extruded through
the nozzles in the pressure guns, and the extruded polymer strings
were elongated by a number of air streams and broken up so as to
form separate fibres which were deposited on the surface of the rock
fibre webs. All the sides of the webs were coated.
The coating formed had a surface weight of 15 g/m2 and the adhesion
between the rock .fibre material and the coating was satisfactory as
tearing tests showed that tire rock fibre material was spread out in
separate layers before the surface coating was torn off the rock
fibre material. The polyester fibres applied had an average diameter
of about 40 um. The coating was tactile.
Another test series was carried out by use of a melt spray apparatus
comprising means for mixing a gas into the polymer melt. The
remaining characteristics of the apparatus were identical with those
of the apparatus used in the initial test row, just as the remaining
test conditions were identical with those used in the initial test
series.
In this test series a synthetic hot melt marketed under the name
Henkel Q2279 was used as a polymer material.
WO 93/15814 ~'~ PCT/1aK93/(l0064
16 .".
The polymer was melted in a melting vessel at a temperature of about
160'C, and subsequently a foaming gas in the form of nitrogen was
admixed with the melt and the mixture of melt and gas obtained was
then extruded through the nozzles in the pressure guns.
The extruded melt/gas mixture was then elongated by a number of air
streams and broken up so as to form separate fibres which were
deposited on the surface of the rock fibre webs. All the sides of
the webs were coated.
The surface coating formed had a surface weight of 15 g/m2, and the
adhesion between the rock fibre material and the coating was
satisfactory, as tearing tests showed that the rock fibre material
was broken up in separate layers before the surface coating was torn
off the rock fibre material.
The polymer fibres applied had an average diameter of about 80 dun,
and the netting formed covered a greater portion of the surface of
the rock fibre material than the netting formed in the initial test
series, but the netting consisting of foamed fibres was still
permeable to air, however.
The coating formed in the second test series had an increased
tactility and rock fibre retention capacity as compared to the
coating formed in the initial test series.
35
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