Note: Descriptions are shown in the official language in which they were submitted.
~;~41533
The invention concerns a process for the continuous
production of fiber reinforced webs.
Fiber reinforced wets are made of highly diverse
elastic materials, in which, in addition to the use of raw
materials, recycled materials are being increasingly utilized.
It is known from DE-OS 2 162 233 to mix granulated,
irreversibly crosslinked elastomers with a thermoplastic
binder, heat the mixture to a temperature above the melting
point of the binder but under the decomposition temperature
of the elastomer, extrude it as a film from a sheet die and
cool it between cooled belts of a double belt press to a
temperature under the melting point of the binder.
DE-AS 1 089 954 discloses a process for the production
of plates or products of other shapes from waste rubber and
textile fibers in which impregnated textile filaments ob-
tained from cord inserts of used automobile tires by cutting,
breaking and grinding, are mixed with a small amount of small
pieces of rubber with the addition of binders, such as natural
or synthetic resins or adhesives and the mixtures pressed at
an elevated temperature.
DE-AS 1 038 266 describes a process for the production
of a porous material consisting of textile fibers, in partic-
ular textile wastes and binders, in which the textile fibers
are agglomerated in the dry state into small units and these
fiber agglomerates sprayed with a liquid binder in droplet
form while rotating in a drum so that the binder adheres in
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dots to the surface of the fiber agglomerates, whereupon
under continued rotation of the mass being formed, a harden-
ing agent is sprayed onto it, followed by the shaping,
drying and hardening of the mass.
It is known from the production of rubber to prepare
elastic webs by vulcanizing a masticated web provided with
vulcanizing agents, for example under the action of steam.
It is a common characteristic of all of these known
processes that the unhardened or not yet vulcanized web has
no coherence over its entire surface. For this reason, the
elastic web must be sùpported by a carrier during hardening
or vulcanization. If several unhardened or unvulcanized
webs are placed upon each other, the individual layers must
be separated by separating layers, for example silicone
paper. It is not possible to freely move such webs in an
unsupported manner, even if for example a masticated rubber
sheet is involved.
It is therefore an object of the invention to provide
a process for the continuous production of fiber reinforced
webs whereby the webs possess their own internal coherence,
in particular a fiber reinforcement, even in the unbonded
or unvulcanized condition.
The object is attained by the production of fiber rein-
forced webs wherein an elastic, unfoamed material is placed
as a core layer between a substrate layer and a cover layer,
with at least one of the outer layers comprising actively
needle bondable fibers thereby forming a composite which is
then needle bonded together. The process of needle bonding
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41533
known in the textlle industry is used to achieve the needle
bonding.
In the so-called needle bonding process, individual
fibers or bundles of fibers are inserted from a fiber con-
taining layer placed upon another layer by means of needles
equipped with barbs into the second layer, in which the
fibers remain upon the withdrawal of the needles, thereby
bonding the fiber containing layer to the second layer. A
requirement of the needle bonding process is thus the presence
of a layer of ''actively needle bondable materials", i.e., a
layer consisting of fibrous structures usable for the needle
bonding process, or containing such structures. The other
layer, in which the actively needle bondable fibers are in-
-- serted must be at least partially needle bondable, i.e., it
must be capable of holding the inserted fibers.
Such a passively needle bondable layer may itself be
; actively needle bondable, but-passively needle bondable layersmay also be formed in a known manner of woven tissue, knits,
spunbonds, paper or synthetic plastic sheets, or the like.
Both the cover layer and the substrate layer may be
built up of several layers. Thus the substrate layer may
consist of a synthetic plastic sheet and a fiber fleece,
wherein for example the sheet is facing the core layer.
It has now been surprisingly discovered that an elastic,
unfoamed material, such as for example granules of vulcanized
rubber, of waste rubber or specially prepared, synthetically
pxoduced, unfoamed elastomers, granules with or without
binders obtained from needle bonded felt floor coverings, or
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even unvulcanized rubber sheets provided with auxiliary
vulcanizing agents, in particular plasticizers, may be
needle bonded as the core layer between two outer layers to
these outer layers.
By means of the needle bonding of webs of individual
layers a plurality of holding fibers may very rapidly be in-
serted with a relatively high density into a core layer of
unbonded or unvulcanized elastic material whereby the three
layers are held together and the elastic materials present in
the core layer, together with the potentially added fillers,
such as sand particles or the like, are prevented from pene-
trating into or through the outer layers.
The fiber reinforced elastic web has its own internal
coherence and may be manipulated without a carrier or support
surface in a freely suspended manner.
Webs of this type may further be used as an elastic floor
in sport or recreational installations, with these unbonded
or unvulcanized webs being placed on the floor to be covered
;~ and for example previously provided with an adhesive layer,
in order to bond the web to the substrate. This web, adhes-
ively bonded to the~floor, is then impregnated with a liquid
binder, for example a two-component adhesive such as poly-
urethane, and the bonding properly effected with the web
installation.
Conventional synthetic fibers of polyester, polyamide,
polypropylene or the like, or natural fibers, such as cotton
or the like, may be used as the actively needle bondable
fibers, with the choice to be effected with regard to the core
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layer to be needled and the desired properties of the
finished web. The second outer layer, which as mentioned
hereinabove, must be at least passively needle bondable, may
consist of the same fibers, but the aforementioned webs may
also be used.
The needle bonding of the three layers leads to the fact
that the particles not bonded to each other and the mass of
the core layer are not only held between the two outer layers,
but are prevented from substantially shifting in the plane of
the extent of the web. The solid particles uniformly distri-
buted in the manufacturing plant and inserted with a constant
layer thickness thus remain even without bonding or vulcan-
izing in their predetermined position. This is true even if
orifices, such as punched holes, slits, or the like are
applied transversely to the plane of the web.
According to a preferred embodiment, the core layer
consisting of an elastic, unfoamed material comprises granules
which cannot be pierced during needle bonding. The grain size
of the granules is chosen in accordance with the final thick-
ness desired of the web, preferably, not more than 5 mm. It
is, however, also possible to needle bond larger granules; in
such cases the stitch density, i.e., the number of needle
stitches per unit surface should be lower and bonding needles
with a larger diameter should be used. The needle bonded
holding fibers are then always located between two or more
particles. As a consequence of the elasticity of the granules
and the internal pressure generated by the needle bonding, the
Ayers are compressed during needling with this densification
3L24~S3;:'
being maintained by the holding fibers, the contact surfaces
between the granulated particles are increased so that when
the granules have an at least rough surface, the particles
are prevented from slipping even among themselves.
According to another embodiment, the granules are made
from vulcanized rubber, i.e., granulted. This may involve
processed rubber waste, obtained for example from used tires
or the like. However, a rubber mixture prepared specially
for the purpose may also be vulcanized and granulated. It is
possible in the process to mix certain desirable additives
into the masticated rubber mass. It is further feasible to
use as the core layer a mixture of waste rubber with its
existing properties and a separately prepared rubber with the
desired properties. The waste rubber used may further contain
reinforcing fibers, such as cord~inserts or the like. Prior
to needle bonding, fillers, such as sand partlcles or the like,
may be-mixed with the core layer. When this web is needle bonded
it offers a coherence to such a mixture; which in known webs,
may be obtained only by hardening, for example, by vulcanizing.
the same is true in the case wherein the core layer
consists of rubber granules and/or fillers and foaming elas-
tomers, which may be foamed at a much later time. Such foaming
elastomers may be present in the form of granules or spheres
and may consist of rubber or a synthetic material provided
with foaming agents.
According to a preferred embodiment, the rubber particles
and possibly the filler particles are provided with a coating
prior to their insertion between the two outer layers. The
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53;:~
coating may consist of a binder activated by heat and/or
pressure, the binder being activated only after the needle
bonding of the web.
According to a further feature, the coating consists of
one component of a two-component binder, with the second
component of this binder being introduced, at the earliest,
after the needle bonding of the web, preferably at the
location where the needle bonding is performed. The second
component may be in a liquid or powder form. ThuS, such a
web provided with one component of the binder, may be rolled
out on sport fields, whereupon the second component of the
binder is sprayed or sprinkled on.
According to a further embodiment, the coating of the
particles consists of a slip additive, whereby the sliding of
the bonding needles during their insertion along the particles
is facilitated and the particles are able to avoid the~needles
by a slight lateral shift. After needling, the slip additive,
especially when heat is introduced, may evaporate or volatilize.
However, such an additive may also effect cross linking between
the individual rubber particles or may be absorbed slowly by
the granules without significantly affecting the properties of
the latter. Water may be used as a slip additive.
The elastic, unfoamed granule particles may further be
coated with a swelling agent, with the surface of the par-
ticles swelling to a variable depth. This swelling facilitates
the penetration of the core layer by the needles, as not only
is the surface of the particles becoming softer, but particles
hooked onto the barbs of the needles may be torn out of the
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~4~33
granules without significantly altering the position of the
latter. The swelling agent is preferably removed after needle
bonding, for example in successive hot calenders.
Granules obtained by the granulating of needle bonded
floor coverings may also be considered as an elastic, unfoamed
material forming the core layer. In the manufacturing process
of needie bonded floor coverings, as a rule as the last work
step the so-called selvedge, which as the result of its edge
location contains irregularities, is cut off. At the beginning
and the end of a floor covering there are further areas which
do not meet a predetermined quality standard of the floor
covering and which therefore are considered waste. The
elasticity of such a needle felted floor covering, which
heretofore has been considered unusable was$e, may now be
utilized by granulating these waste strips or areas into
particles with a grain size of for example 2-5 mm and using
them as the core layer in the process according to the inven-
tion. The granules are preferably present in the form of small
clusters of fibers, bonded preferably at least in part by a
binder of rubber latex. If a top layer is used containing
coarse, actively needle bondable fibers, for example having
a fiber titer of 100 dtex, and these coarse fibers are placed
with a low weight per unit area on the core layer so that the
core layer is not completely covered, and the fibers are active-
ly needle bonded, the granules of the core layer will remain
visible between the fibers. A web is obtained in this manner
which again may be used as a carpet, which, especially if the
granules are of different colors, displays an optically pleasing
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533
walking surface. The elastic properties of this web corres-
pond essentially to those of the aforedescribed webs consist-
ing essentially of rubber particles.
In the above-described needle bonding of rubber
particles, the needle process provides the particles which are
not bonded together with an internal coherence. If an elastic,
unfoamed material is used as the core layer in the form of a
rubber sheet treated with vulcanizing agents, the latter receives
a fiber reinforcement which reinforces the rubber sheet even
before vulcanization. Unvulcanized rubber sheets may be
altered in their shape very easily as the result of their
plasticity, especially if they are to be handled without a
support or carrier surface. This starts as a reduction in
cross section and leads by way of a edge tear to tne complete
rupture of the sheet.
Even though the insertion of the bonding needles creates
openings which act to weaken the rubber sheet, the fact that
simultaneously the reinforcing fibers are mechanically bonded
to the rubber sheet enhances the inherent stability of such a
web. The openings created by the needles are reclosed by the
plasticity of the rubber sheet and the pressure applied by the
two outer layers to the rubber sheet. In particular,the needle
bonded webs containing rubber or carpet granules and possibly
fillers, may be impregnated or coated with a binder in the
manufacturing plant or at a later application site, wherein
the binder may consist of latex, liquid rubber, bitumen, modi-
fied polyurethane, a duroplast or construction cement. Such
a web may further be impregnated or coated with a solvent,
_g_
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~;24~3~
whereby cross linking is induced between the individual rubber
components.
According to one form of embodiment, the needle bonded
we is pressed or calendered, in particular compression molded
or calendered, with this operation effected prior to the vul-
canization or simultaneously with vulcanization of the web.
Vulcanizing may be performed in a known manner, for example
with the application of heat and/or pressure. At least the
holding fibers connecting the two outer layers are fully bonded
into the vulcanizing rubber mass during the vulcanizing pro-
cess. If for example, liquid rubber has been applied to a
needle bonded web and the web is vulcanized, then at least the
outer layer on the side of the application of the liquid rubber
is bonded into the rubber mass, so that for example no layer
containing fibers or a tissue is visible on the vulcanized
web.
It is further possible to have an outer layer containing
fibers or a fabric of such a thickness that even after vulcan-
izing only these fibers or the fabric are visible, thereby
lending the character of a textile to the web. An interesting
structure may be obtained by choosing a fiber layer such that
even though the fibers remain visible from the outside after
vulcanizing, the center layer containing rubber is recognizable
between the fibers. A similar effect may be achieved for a
web into which textile wastes have been worked, whereby,
especially if textile wastes of different colors are used and
they remain visible after needle bonding, an interesting color
effect may be achieved.
~.24~S33
In addition to the aforementioned pressing or calen-
dering the needle bonded web may also be shaped, in particular
wound, whereupon the web is vulcanized or bonded in this form.
According to a special embodiment, fibers shrinkable
by heat are used as the actively needle bondable fibers and a
shrinking process effected after the needle bonding whereby
the core layer is further densified.
The webs described hereinabove may be used as carpets.
In contrast to conventional carpets, which in most cases are
coated from the direction of the substrate layer with latex
or the like, whereby the fibers are further bound for needling,
the new webs present a carpet in which the additional bonding
is not applied from the outside, but is inserted as the core
layer prior to needle bonding.
Depending on how tightly the cover layèr-, wpich usually
contains the actively needle bondable fibers, is formed, the
core layer containing the elastic material is visible to a
greater or lesser extent through the cover layer. It is,
however, possible to make the cover layer tight enough so that
~20 the core layer containing rubber particles or the like, is
not apparent at all, whereby the web according to the invention
displays the appearance of a conventionaI needle felt floor
covering, which, however, may be more elastic than the known
floor coverings.
The fibers of the cover layer, resting for example on
rubber particles and representing the walking surface, provide
a sliding surface for the web essentially consisting of rubber,
while the rubber core layer prevents the penetration of water
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533
and dust particles into or through the web.
Further forms of embodiment and advantages of the
invention will become apparent from the following examples of
embodiment.
In the drawing
Fig. 1 shows a schematic illustration of an instal-
lation for the embodiment of the process;
Fig. 2 shows a schematic view of a section through a
needle bonded web containing rubber particles and fillers
prior to vulcanizing;
Fig. 3 shows a schematic view of a section through a
needle bonded elastic web, in which foaming elastomers have
been foamed;
Fig. 4 shows a schemativ view of a section through a
needle bonded web vulcanized in molds; and
Fig. 5 shows a needle bonded elastic web bonded by
needling with a needle felt web.
According to Fig. 1, a substrate layer 2 is deposited
onto a conveyor i'nstallation, here a conveyor belt 1, onto
which, here by means of a metering discharge device 3, the
core layer 4 is placed. Actively needle bondable fibers,
here in the form of a fiber fleece 5, are deposited onto the
core layer 4, whereupon this three layer system is transported
to a needle machine 6.
Such needle machines 6 are known from the textile needle
felting technology (see: for example Krcma, "Manual of
Nonwovensl; page 233 to 23~). In a needle machine of this type
the system to be needle bonded, here the three layer system,
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S3~
is guided over a base plate 7 provided with bores. A needle
board 9 carrying the needle bonding needles 8 is arranged
above the object to be needled, which board is moving constantly
up and down (double arrow 10) far enough so that the needle
points ll in their lowest position are penetrating entirely
through the object to be bonded, while in their uppermost
position they have no contact with the object. In this upper-
most position the object to be bonded, here the three layer
system, may be displaced narrow 12) cyclicly in the advance
direction, while it must be at rest during the needle bonding
itself. The needle bonding needles 8 carry on their shaft at
least one -- here two -- barbs 13, whereby they grip individual
fibers or bundles or fibers and draw them into or through the
object to be bonded. Upon the retraction of the needles, the
fibers or fiber bundles entrained are released from the barbs
13 and remain in the passively bonded layer, here the sub-
strate layer 2 and the core layer 4.
While in the needle bonding process in the textile
industry, in the production of needle felted carpets with a
final thickness of for example 4-6 mm, the needle boards have
a plurality of needles arranged in close proximity to each
other and may be moved for example with a velocity of 700
strokes per minute, for the needle bonding of elastic, unfoamed
materials, such as rubber granules, foamable elastomers, mas-
ticated rubber sheets or granules of carpets, to which filler,
such as sand particles, may be added, the density of the needles
8 in the needle board 9 must be increased and the number of
strokes greatly reduced.
-13-
24~53~3
If these criteria are satisfied, a layer containing
the aforelisted materials may be subjected to a needle bonding
process, wherein the needles are sliding along the rubber or
filler particles and possibly slightly shift them aside lat-
erally. This sliding and lateral shiftlng may be facilitated
by providing the particles with a coating which promotes slip-
ping.
As seen in Fig. l, the thickness of the three layer system
is reduced during needle bonding, as firstly the fiber contain-
ing layer 5 is densified by the needling and secondly thls
fiber layer 5 and, depending on its configuration, also the
substrate 2 is drawn or pressed into the boundary areas of the
core layer as the result of the elasticity of their materials.
Furthermore, the elastic material of the core material itself
will be somewhat compressed and remains under a certain stress.
Because of the elasticity of these particles the contact sur-
faces themselves may yield. By means of this compression, the
subsequent vulcanizing of the web consisting of individual
grains is facilitated even if no additional binders, such as
latex or liquid rubber, are added.
According to the form of embodiment of the installation
for the operation of the process according to the invention,
the needle bonded elastic web is guided between two calender
rolls 14 and 15, whereby, especially if they are heated, vul-
canization may be effected. The two calender rolls 14 and 15,
are pressured against each other while transporting the web
between them and applying a pressure of 2-5 bar/cm2.
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~24~53~
The elastic web 16 leaving the calender rolls has a
thickness that is not significantly less than that of the
web 16 prior to calendering, as the elastic material expands
again after calendering.
Fig. 2 shows a needle bonded web 16 containing rubber
particles 17 and filler particles 18 in an enlarged and
schematic view, wherein it is seen that the substrate layer
2 is connected with the cover layer 5 by means of the holding
fibers 19, which extend through the core layer 4. In the
form of embodiment according to Fig. 2 the substrate layer 2
and the cover layer 5 consist of actively needle bondable
fiber fleece. The web 16 is here needle bonded from both of
the outer sides, which may be seen by the "fiber funnels" 20,
formed at the insertion points of the needles 8. Ends and
parts of fibers not seized by the barbs 13 are drawn partially
into these fiber funnels 20. The holding fibers 19 passing
through the web 16 are distributed irregularly over the surface
of the web and therefore in a section through such a web in
actual practice only very few holding fibers 19 may be seen.
Fig. 3 shows a needle bonded elastic web in which foamable
elastomers 21 and filler particles 18 were bonded, whereupon
the elastomers were foamed by the activation of the foaming
agents. The foamed elastomers 21 fill not only the inter-
stices between the filler particles 18, but also contribute
to the outward pressure applied to the fibers in the outer
layers 2 and 5, leading to a surface structure with small
convex bulges of the web. In order to prevent the bursting
of the web 16, it is advisable especially in this case to
~L2~533
needle bond the web from both sldes, ln order to maintain an
adequate mechanical connection between the two outer layers.
The foaming process may also be effected in a double belt
press so that the foaming of the elastomers 21 will be
opposed by a further, external resistance. In Fig. 3, the
foamed elastomers 21 are shown by shading. Even though it
appears therein that the holding fibers 19 are passing through
the elastomer 21, they have merely been completely surrounded
by it during the foaming process.
To produce the web 16 shown in Fig. 4, rubber granules
and filler particles 18, for example grains of sand, are
placed between two prebonded fiber fleece sheets, needle
bonded from both sides and then vulcanized in a molding press.
This molding press, for example a double belt press, had on
one sidè a flat, closed surface, whereby the side of the web
at the bottom in Fig. 4 was given a smooth surface, while the
other side of the press had a flat surface, in which a plurality
- of orifices were provided in a spaced apart manner, so that
the web in the area of said orifices was compressed less than
in the adjacent areas. The vulcanized web thereby obtained
the nap 22 seen in Fig. 4, which is protruding over the sur-
face of the web 16. In the region of the nap 22 the web 16
is slightly more elastic than in the adjoining areas.
By using thicker, prebonded fiber fleece webs as the
cover layer 5 and/or the bottom layer 2, a web 16 may possibly
have the character of a textile on both sides. If such a web
is placed on an especially smooth and slippery surface, there
is a danger of the web slipping. This may be remedied by
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3 241533
cutting of the upper part of one nap 22, as shown in Fig. 4
on the right hand nap, whereby within this area the vulcanized
rubber layer will come to the surface. If such a web 16 is
placed with its cut nap 22 on a smooth floor so that the pro-
truding nap is resting on the floor, i.e., inversely to wha-t
is shown in the drawing, the cut off nap is acting as an
assurance against slipping. Fig. 5 shows a needle bonded
elastic web 16, to which a needle felted 23 has been needle
bonded. The holding fibers 24 taken from the needle welt web
23 were needled into the elastic web 16, whereby the two webs
are mechanically bonded to each other. This needle bonding
of the two webs 16 and ~3 may be effected both prior to the
vulcanizing of the elastic web 16 and after it.
According to an example of embodiment, not shown, a
masticated rubber sheet provided with vulcanizing agents, is
placed between the substrate layer and the cover layer and
the three layers needle bonded to each other. Such a web
may be manipulated freely, i.e., without a support or carrier
layer, without the risk of a change in the thickness of the
rubber sheet, of edge tearing or breaking. In place of the
discharge device 3 shown in Fig. 1, feeding is effected for
example by a belt conveyor or from a roll.
A further form of embodiment, not shown separately, that
may be prepared with an installation according to Fig. 1,
consists of granules with a grain size of 2-3 mm, made from a
needle felted floor covering, as the core layer, which is
placed between the two layers 2 and 5 and then needle bonded.
Granules of this type are present in the form of clusters of
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~L.2~1533
fibers and in part contain rubber latex. The cover layer 5
consists of coarse fibers, for example Dorix fibers, which
are placed in a noncovering manner onto the core layer.
After needle bonding, the core layer consisting of granules
of the needle felted floor covering is apparent through the
cover layer. By using variously colored granules, for example
from different batches of carpet manufacturing, a pattern may
be produced. It is possible here again to coat such a needle
bonded web 16 with liquid rubber, in order to obtain further
strengthening of the particles.
In the above-described examples of embodiment inserts may
further be placed into the web prior to needle bonding. It is
thus feasible to apply the core layer not by means of the
discharge device 4, but to provide several discharge means and
to insert between these discharge means cord filaments of a
synthetic material or steel wires. Such filaments may be
needle bonded as described hereinabove for filler materials.
Metal platelets may be inserted, but precautions must be taken
that no needles are inserted in the bonding process in the
area of the metal platelets.
The filaments or metal platelets are first suitably pro-
cessed so that in the vulcanizing process an adhesive effect
will be present between the rubber mass and the inserts.
EXAMPLE:
Two identical fiber fleeces of polyester fibers with 70%
fibers with a titer of 6.7 dtex and 30~ fibers with a titer of
17 dtex, with a weight per unit area of 115 g/m2 and a Bafatex
support with a weight by unit area of 25 g/m2, were prepared
-18-
~Z~iS33
- by needle bonding from both sides with a stitch density of
24 stitches/cm2.
Rubber particles with a grain size of l mm were placed
onto one of the fiber fleeces with a weight per unit area of
3.7 kg/m2, covered with the other fiber fleece and needle
bonded with a switch density of 24 stitches/cm2.
The bonded web was covered with 720 g/m2 of a 1:1 mixture
of latex and water and dried at 130C for four hours.
An elastic web with a thickness of 4 mm was obtained.
As a swelling agent benzol or light oil can be used.
These swelling agents can be removed by heat after needle
bonding the web.
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