Note: Descriptions are shown in the official language in which they were submitted.
CA 02449733 2003-12-O1
s
P 32951
Method and device for treating a fibre mass
The invention relates to a method for treating a fibre mass, such as a woven
cloth or
a nonwoven, where the fibre mass is conveyed through a pressing mill, where
the
fibre mass is pressed in at least one pressing zone by the pressing surface
area of at
least one press-roll by means of a pressing power acting on the fibre mass,
and the
pressed fibre mass is impregnated with a treatment fluid, the fibre mass being
passed through an expansion region in the pressing zone where the pressing
power
is reduced in the passing direction of the fibre mass.
i
The invention further relates to a press-roll arrangement for treating a fibre
mass
moving relatively to the press-roll arrangement, comprising a press-roll with
a press-
ing surface area by means of which in operation in a pressing zone a pressing
power
acting on the fibre mass is generated, and with an impregnation means by which
in
operation a treatment fluid is supplied to the fibre mass, the pressing zone
forming an
expansion region in operation in which the pressing power is reduced in the
moving
direction of the fibre mass.
The term pressing surface area designates the surface which limits, as an
imaginary
or actually existing surface area, the pressing zone from the upper or lower
side of
the fibre mass, i.e. the idealized enveloping surface via which the pressing
power
acts on the fibre mass.
For preparing the fibre masses concerned by the invention, conventionally a
poly-
meric mass is melted or dissolved in a solvent and subsequently drawn over
spinning
devices to form filament yarns. For preparing the filament yarns, various
spinning
processes, such as dry spinning and wet spinning methods or a combination of
dry
3o and wet spinning methods, are possible. In the process, the filaments are
generated
in a spinning machine and drawn off from the same by one or more draw-off ele-
ments being at the same time formed to filament bundles or tows. Subsequently,
the
filaments are washed and aftertreated in further processing steps.
CA 02449733 2006-O1-27
2
Before the aftertreatment, for example, in the manufacture of staple fibres,
the tow of
filament yarns arranged in parallel which is drawn off from the spinning
machine is
supplied to a cutting device. After exiting the cutting device, in general a
nonwoven is
formed from the individual staple fibres and deposited on a transport device
to be
further treated.
The staples are generated by staple cutting machines, for example in a dry cut
by the
machine described in Chapter 11 of Ullmanns Encyclopedia of Technical
Chemistry, 4~'
edition, 1976, by Dr. Befa von Falkai titled "Fibers, Manufacturing Method",
pages 249-
289.
Viscose fibres are spun in general in aqueous media as cellulosic regenerated
fibres.
For the staple fibre generation from the continuously spun fibre tow, for
example a
cutting machine is suitable which essentially consists of a pair of rolls for
feeding the
spinning tow to the cutting apparatus, the actual cutting apparatus and a
staple fibre
I S washing-down device. The cutting apparatus draws the tow fed by the draw-
off ele-
rnent by means of a water jet injector to the horizontally rotating cutting
knives. The
cutting knives maintain their edge retention during the cutting process by a
continu-
ous regrinding. Moreover, by the water jet supply, a first dissolution of the
staple fibre
stacks formed during the cutting process is effected before the suspension of
the
staple fibre stacks at the aftertreatment machine. Such a machine is for
example
manufactured by the company Ing. A. Maurer S.A.
The aftertreatment of for example viscose fibres can or must be effected by
various
treatment steps. In the process, in aftertreatment machines for viscose
fibres, typi-
tally the following treatment steps are carried out while supplying a
treatment fluid:
deacidification, desulphurization, washing, bleaching and washing,
antichlorine
treatment, washing with water as well as applying an avivage or a fat coat.
These
treatment steps are conventionally carried out in a device to which the cut
staple fi-
bre, also designated as "flock", comes from the cutting machine via a washing-
in de-
vice while forming a nonwoven coat distributed as uniformly as possible.
The device for treating the fibre mass is conventionally formed as a long
aggregate in
which the fibre mass distributed to a uniform nonwoven or the fibre mass,
respec-
CA 02449733 2003-12-O1
3
tively, is conveyed on a transport means through the individual treatment
zones. As a
transport means, a belt conveyor, for example with an endless travelling
screen or an
endless wire-cloth belt, an oscillating conveyor or an eccentric notched
conveyor can
be used.
In the treatment of the fibre mass, care has to be taken that the treatment
fluids sup-
plied in the individual treatment steps are quickly and homogenously
distributed in
the suspended nonwoven.
l0 At the same time, it is advantageous to remove the treatment fluid from the
previous
treatment step as completely as possible from the fibre mass before carrying
out a
treatment step.
For removing a treatment fluid from the fibre mass, conventionally a press-
roll ar-
rangement is used which exerts a pressing power on the fibre mass. By means of
the
pressing power, the treatment fluid is pressed out of the fibre mass. In the
subse-
quent treatment step, the pressed fibre mass is then impregnated with the
treatment
fluid associated to this treatment step. That is, by means of the press-roll
arrange-
ment, two subsequent treatment steps are separated.
In the region where the pressing power acts on the fibre mass, i.e. the
pressing zone,
shortly after the point of the highest pressing power, a region is formed
where the
pressing power is reduced in the conveying direction of the fibre mass. This
region is
designated as expansion region.
In order to moisten the fibre mass with the treatment fluid, conventionally
the fibre
mass is passed below spray tubs on a transport device. Directly after the
pressing
out, the treatment fluid is dripped onto the fibre mass by spray installations
positioned
thereabove. However, the application of the treatment fluid by dropping only
effects a
nonuniform impregnation and moistening of the fibre mass just pressed.
A special problem arises in the preparation of cellulose fibres or nonwovens
of ceilu-
lose fibres which are prepared by an NMMO or lyocell process. In the process,
a
CA 02449733 2003-12-O1
4
spinning solution containing water, cellulose and tertiary amine oxide is
extruded to a
filament yarn and drawn.
During the drawing, the cellulose filaments are exposed to a high mechanical
stress.
The filaments and staple fibres prepared according to the NMMO or lyocell
process
comprise a high crystallinity or orientation of the cellulosic molecules,
respectively.
Due to these product features caused by the manufacturing process, lyocell
fibres
tend to be fibrillary. Fibrillation means that due to the high crystallinity
and orientation
small fibrils split off the circular fibre surface of an individual fibre. The
formation of
l0 fibrils continues along the fibre axis.
In order to reduce the tendency of fibrillation, the fibre can be treated with
chemical
cross-linkers which bind the fibrillary elements to the fibre main body. In
general, an
interlacing or cross-linkage process is controlled such that the ceilulosic
fibre tow is
impregnated with a chemical cross-linking agent and the cross-linking reaction
is
started by vaporization at elevated temperatures.
The cross-linking agents have to be homogenously introduced into the fibre
mass
after the fibre preparation, the temperature of the fibre optionally has to be
controlled
and washed out of the fibre in subsequent treatment steps. Moreover, the
cellulose
fibre has to be brightened and dried, as other non-cellulosic fibres as well.
In this treatment, it is problematic that the cross-linking agents tend to
spontaneous
chemical degradation or hydrolysis reactions as the chemicals hydrolise in an
aque-
ous medium or are not stable for a long time, respectively. If the reaction
parameters
- for example the reaction rate or the reaction temperature - are not exactly
ob-
served, degradation or decomposition reactions can also occur. Therefore, the
cross-
linking agent has to be introduced in closed regions while controlling the
reaction
course as exactly as possible. Usually, the cross-linking agents require a
quick intro-
duction into the cellulose fibre with a subsequent quick control of the
temperature as
well as subsequently a washing out of the remaining chemicals as fast as
possible
with a cooling-down at the same time. During the so-called cross-linkage,
elevated
temperatures as well as alkaline or acid liquids act on the fibre mass. The
chemical
CA 02449733 2003-12-O1
reaction of the cellulose with the cross-linking agent is effected at elevated
pH-values
(for example approx. 11 -14), resulting in a hydrolysis of the cross-linking
agent. The
cross-linking agent's tendency of decomposition can be repressed by the
tempera-
tures in the cross-linking bath being as low as possible. The low temperatures
can be
5 adjusted in or in front of the pressing device. After the thermal fixation
of the cross-
finking agent, i.e. the reaction of the cross-linking agent with the cellulose
chains
between approx. 20 and 98°C, the alkali has to be removed from the
fibre mass for
reducing the strain on the celluiosic fibre.
Due to the high fibre density and fibre swelling in cellulosic fibre masses,
moreover
long dwell times for penetrating the fibre mass are necessary, as only a low
geodetic
height of the liquid positioned thereabove acts on the nonwoven and the
pressure
losses of the nonwoven can only be overcome by a long action duration of the
fluid.
The conventional method and the conventional device, where the pressed fibre
mass
is only sprayed with a treatment fluid, are not sufficient for a precise
control of the
process parameters exactly in treatment fluids which chemically react easily
or de-
compose, such as cross-linking agents.
In view of the methods and devices conventionally employed for treating fibre
masses, it is therefore an object of the invention to improve the method
mentioned in
the beginning and the device mentioned in the beginning, respectively, in such
a way
that a distribution of the treatment fluid, the temperature-controlling agent
(hot water,
hot vapour and optionally other heat transfer media) as well as various
washing me-
dia in the fibre mass as fast and homogenously as possible and thus also an
exact
process control are possible.
This object is achieved for the inventive method mentioned in the beginning in
that
the treatment fluid is passed into the fibre mass in the expansion region
through the
3o pressing surface area.
In the press-roll arrangement mentioned in the beginning, this object is
achieved in
that the press-roll arrangement comprises openings in the expansion region
through
CA 02449733 2003-12-O1
6
which in operation the treatment fluid is passed through the pressing surface
area
into the fibre mass.
This solution is simple and has the advantage that the treatment fluid very
quickly
and homogenously distributes in the pressed and compressed fibre mass which re-
laxes in the expansion region. As in the expansion region the pressing power
is re-
duced in the moving direction of the fibre mass, in this region the fibre mass
auto-
matically takes in the treatment fluid through the pressing surtace area.
Thus, a uni-
form and quick penetration of the pressed fibre mass with the treatment fluid
already
takes place in the pressing zone. Thereby, the treatment process is easier to
control.
The solution according to the invention has the further advantage that the
overall
length of a treatment machine can be essentially reduced. In contrast to the
conven-
tional machines, where due to the spraying a penetration of the fibre mass is
only
possible by means of a long action time and a correspondingly longer conveying
distance of the fibre mass through the treatment zone, with the solution
according to
the invention due to the immediate penetration the next treatment step can
directly
follow the impregnation of the fibre mass with the treatment fluid.
That is, with the solution according to the invention, it is possible to
design the
pressing mill similarly to a rolling mill where the individual rolls directly
follow one an-
other in the direction of rolling. According to a further development of the
invention,
accordingly in the treatment of the fibre mass several treatment steps can be
carried
out successively by passing the fibre mass successively through several press-
roll
arrangements, in one press-roll arrangement each a first treatment fluid being
pressed out of the fibre mass in the compression zone and the fibre mass being
im-
pregnated with a second treatment fluid in the expansion zone.
The fibre mass can be conveyed through the pressing zone by means of a
separate
conveying means, for example in the form of a conveyor belt, the press-roll
passively
rotating along. However, the press-roll can also be provided with an own
driving
means. In this case, one can dispense with a separate conveying means, as the
press-roll itself forms the conveying means. The peripheral speeds of the
press-rolls
CA 02449733 2003-12-O1
7
can be between 0.1 and 400 mlmin, preferably between 0.1 and 60 mlmin, in par-
ticular between 0.1 and 10 mlmin. With these peripheral speeds, in a treatment
zone
a fibre throughput of 10 to 1500 kg/(m2h), preferably between 10 and 1200
kg/(m2h),
can be achieved. The fibre throughput is calculated from the weight of the
fibre mass
in an absolutly dry condition divided by the dwell time per treatment field
and is inde-
pendent of the length of the treatment field.
In front of the expansion region, the fibre mass can be passed in the pressing
zone
through a compression region where the pressing power is increased in the
convey-
ing direction of the fibre mass, so that a treatment fluid already present in
the fibre
mass is pressed out. In a further advantageous embodiment, in the compression
re-
gion the pressed out treatment fluid can be let off from the fibre mass
through the
pressing surface area. For doing so, for example a suction means can be
provided
through which in operation the treatment fluid is sucked off from the
compression
region. Instead of a suction means, however, only openings in the pressing
surface
area can be provided through which the treatment fluid automatically passes
due to
the pressing power increasing in the treatment direction in the compression
region,
so that after the passage of the fibre mass through the pressing zone almost
no more
treatment fluid from the previous treatment step is contained in the fibre
mass.
The line pressure with which a press-roll according to the invention is
pressed into
the fibre mass is up to 100 N per mm of the roll width.
As a supplement or alternatively to the letting off or sucking off of the
treatment fluid
in the compression zone, a treatment fluid can also be passed in the
compression
zone through the pressing surface area into the fibre mass for rinsing the
fibre mass
before pressing it. For example, the fibre mass can be rinsed with the
treatment fluid
supplied to the upstream press-roll in the expansion zone, so that no
treatment fluid
from the treatment step which is arranged by the device in front of the
compression
zone in the transport or conveying direction of the fibre mass, can be carried
into the
treatment step which is arranged behind the expansion zone in the conveying
direc-
tion.
CA 02449733 2003-12-O1
g
A thorough and uniform impregnation of the fibre mass with the treatment fluid
can
be achieved if according to a further advantageous embodiment the treatment
fluid is
pressed into the fibre mass under pressure, for example by nozzles arranged in
the
pressing region in the compression andlor expansion region. The liquid
throughput
referring to the press-roll width can be between 0.1 and 125 m3l(h m),
preferably
between 0.1 and 50 m3l(h m), in particular between 0.1 and 20 m31(h m).
A particularly compact construction can be achieved if the impregnation means
l0 through which the treatment fluid is supplied to the fibre mass is arranged
at least by
sections within the press-roll. In this case, according to a further
embodiment of the
invention, the treatment fluid can be conveyed from the inside of the press-
roll
through openings into the fibre mass. For doing so, the press-roll can be
provided
with openings at its surtace facing the fibre mass through which openings the
treat-
ment fluid is conveyed into the fibre mass. The openings can be formed in the
sur-
face of the press-roll regularly or irregularly and for example comprise a
cross-section
which is essentially nozzle-like. The opening degree of the roil, i.e. the
relation of the
surfaces occupied by the openings to the overall surface of the roll, can be
between
1 and 95%, preferably between 3 and 90%, particularly preferred between 3 and
85%.
According to another embodiment, the press-roll can, however, form ribs at its
sur
face facing the fibre mass, which form at least by sections the pressing
surface area
and between which in operation the treatment fluid can be introduced into the
fibre
mass. According to further embodiments, these ribs can extend essentially
trans-
verse to or essentially in the moving direction of the fibre mass.
In order to avoid a carrying away or mixing of the treatment fluids from the
two
treatment steps separated by the press-roll arrangement, according to a
further
advantageous embodiment, the ribs can be designed as a weir which acts against
a
flow of the treatment fluid through the press-roll from the compression region
to the
expansion zone and thus acts against a carrying away of the treatment fluid.
This is
in particular possible if the ribs extend transversely to the moving direction
of the fibre
CA 02449733 2003-12-O1
9
mass. To this end, the height of the ribs can be dimensioned such that in the
pressing zone an upper end of a rib facing away from the fibre mass projects
essentially between the compression region and the expansion region always
above
the level of the treatment fluid in the compression region andlor expansion
region.
In particular in the embodiment of the press-roll with ribs being spaced apart
and
preferably extending transversely to the conveying direction of the fibre
mass, spray
nozzles can be integrated inside the press-roll according to a further
advantageous
embodiment, through which the treatment fluid is directed in operation onto
the fibre
mass preferably in the pressing zone in a spray or jet form. In order to avoid
a con-
veyance of the treatment fluid out of the compression region through the
rotating
press-roll into the expansion region, the nozzles can also be directed to the
com-
pression region in order to dilute or displace the treatment fluid present
therein. A
complete moistening of the fibre mass by the treatment fluid delivered by the
spray
nozzles is achieved if the atomizing cone of the nozzles essentially overlaps
in the
region of the fibre mass or in the pressing zone, respectively.
Depending on the type of the treatment fluid used, the size and weight of the
fibre
mass as well as the composition of the fibre mass, it can be necessary to
regulate
the region via which the treatment fluid is conducted through the pressing
surface
area onto the fibre mass. For doing so, the impregnation means can comprise a
regulation means by which the size and the orientation of the exiting region
of the
treatment fluid in the pressing surface area is regulated. To this end,
according to a
further advantageous embodiment, the regulation means can be designed as a
cover
body arranged in the press-roll with a slot arranged in the press-roll, which
covers
that part of the pressing surface area or the press-roll through which no
treatment
fluid is to pass. This cover body can for example be designed as a tubular
body pro-
vided with a longitudinal slot and rotatably held in the press-roll.
Instead of or in addition to a supply line of the treatment fluid from the
inside of the
press-roll, the impregnation means can comprise a supply line through which in
op-
eration the treatment fluid is conveyed from outside the press-roll
essentially into the
expansion region. This supply line can be arranged according to a further
advanta-
CA 02449733 2003-12-O1
genus embodiment at least in the pressing zone at least by sections between
two
ribs essentially extending in the moving direction of the fibre mass. In this
case, it is
advantageous if the section of the supply line facing the pressing surface
area es-
sentially flushes with the ribs, so that the pressing surface area is as
smooth as pos-
y sible and offers only little frictional resistance with respect to the fibre
mass.
Finally, the invention also relates to a pressing mill for treating fibre
masses with at
least one press-roll arrangement for pressing the fibre masses and with a
conveying
means for conveying the fibre masses through the pressing mill, a press-roll
ar-
10 rangement according to one of the above described embodiments being used.
In a pressing mill with several press-roll arrangements successively arranged
in the
conveying direction of the fibre mass, the press-roll can directly follow one
another.
The pressing mill and the press-roll arrangement can be operated with a fibre
mass
of which the absolutely dry weight per surface unit is between 0.1 to 20
kg/mz, pref-
erably 0.1 to 10 kglm2. As fibre masses, tows or heavy, thick nonwovens can be
af-
tertreated.
As treatment fluids, pure water, aqueous organic or inorganic solvents,
aqueous or
concentrated alkaline solutions or acids, bleaching chemicals, preparation
means or
inert gases, respectively, vapour-like media, heating or cooling media as well
as soi-
vent vapours can be used.
Opposite the press-roll, a further press-roll can be arranged in the pressing
mill in the
region of the pressing zone which serves as counterpressure means for taking
up the
pressing power. This second press-roll can have the same design as the above
de-
scribed first press-roll. In this configuration, the fibre mass is passed
between the two
press-rol Is.
As materials for the press-rolls, metals or plastics can be used the surface
of which
can be rubberized, polished or ground. In order to avoid a damage of the
fibres, the
CA 02449733 2004-03-10
11
edges of the press-rolls and optionally the edges of the openings and ribs
arranged at the press-rolls should be broken.
In one aspect, the present invention provides a method for treating a fibre
mass
(21 ), such as a filament composite, a woven or a nonwoven, wherein the fibre
mass (21 ) is conveyed through a pressing mill (22), in which the fibre mass
(21 )
is pressed in at least one pressing zone (53) through the pressing surface
area
(52) of at least one press-roll (51 ) by means of a pressing power acting on
the
fibre mass (21 ) and the pressed fibre mass is impregnated with a treatment
fluid,
the fibre mass (21 ) in the pressing zone (53) being conveyed through an
expansion region (55) where the pressing power is reduced in the passing
direction (B) of the fibre mass (21 ), characterized in that the treatment
fluid in the
expansion region (55) is conducted through the pressing surface area (52) into
the fibre mass (21 ).
In another aspect, the present invention provides a Press-roll arrangement
(50)
for treating a fibre mass (21 ) moving relatively to the press-roll
arrangement,
comprising at least one press-roll (51 ) having a pressing surface area (52)
through which in operation in a pressing zone (53) a pressing power action on
the fibre mass (21 ) is generated, and having at least one impregnation means
(72, 72a, 72b) through which in operation a treatment fluid is supplied to the
fibre
mass (21 ), wherein in operation the pressing zone (53) forms an expansion
region (55), in which the pressing power is reduced in the moving direction
(B) of
the fibre mass (21 ), characterized in that the press-roll arrangement (50)
comprises openings (57, 58, 71, 81 ) in the expansion region (55), through
which
in operation the treatment fluid is conducted through the pressing surface
area
(52) into the fibre mass (21 ).
In the following, the invention is further illustrated as to its construction
and
function with reference to embodiments.
In the drawings:
Fig. 1 shows a schematic representation of a plant for manufacturing a fibre
mass;
~ . CA 02449733 2004-03-10
11a
Fig. 2 shows a cross-section of a first embodiment of a press-roll arrangement
according to the invention;
Fig. 3 shows a cross-section of a further development of the embodiment of
Fig.
2;
Fig. 4 shows a perspective view of a second embodiment of a press-roll
arrangement according to the invention;
Fig. 5 shows a cross-section of the embodiment of Fig. 4;
Fig. 6 shows a perspective view of a third embodiment of the press-roll
arrangement according to the invention;
Fig. 7 shows a front view of the embodiment of Fig. 6;
Fig. 8 shows a cross-section of a fourth embodiment of a press-roll
arrangement
according to the invention.
First, the course of the method for manufacturing the fibre mass is described
with reference to Fig. 1.
In a system 1 only schematically represented in Fig. 1, an extrusion solution
2 is
prepared. To this end, in one or more mixers a suspension of dry or wet
crushed
cellu-
CA 02449733 2003-12-O1
12
lose and water andlor tertiary amine oxide is formed. Employing elevated
tempera-
tures at low pressure, water is volatilised from the suspension to such an
extent that
a cellulose solution serving as an extrusion solution is formed. In a reaction
vessel 1,
an extrusion solution 2 is prepared. The extrusion solution contains
cellulose, water
and tertiary amine oxide, such as N-methylmorpholine-N-oxide (NMMO), as well
as
optionally stabilisators for thermally stabilizing the cellulose and the
solvent.
Examples of stabilisators are: propyl gallate or media having alkaline effects
or
mixtures thereof. Optionally, further additives can be contained, such as
titane
dioxide, barium sulphate, graphite, carboxymethylcelluloses, polyethylene
glycols,
l0 ketine, ketusane, alginic acid, polysaccharides, colorants, antibacterially
acting
chemicals, flame protection agents containing phosphor, halides or nitrogen,
active
carbon, carbon blacks or electroconduetive carbon blacks, silicic acid as well
as or-
ganic solvents as diluting agents, etc.
The extrusion solution 2 is delivered through a line or conduit system 4 via a
pump 3.
In the line system 4, a pressure compensation vessel 5 is arranged, which com-
pensates pressure and/or volume flow fluctuations in the line system 4, so
that an
extrusion head 6 can be continually and uniformly provided with the extrusion
solution 2.
The line system 4 is provided with means to control the temperature (not
shown) by
which the temperature of the extrusion solution 2 taken as an example herein
can be
precisely controlled, as well as with a filtration unit (not shown). This is
necessary, as
the chemical and mechanical characteristics of the extrusion solution greatly
depend
on the temperature. Thus, the viscosity of the extrusion solution 2 is reduced
as the
temperature andlor the shearing rate are increased.
in the line system 4, furthermore bursting protection means are provided,
which are
necessary due to the tendency of the extrusion solution towards a spontaneous
exothermic reaction. Due to the bursting protection means, in case of a
spontaneous
exothermic reaction, damages of the line system 4 and the pressure
compensation
vessel 5 as well as the downstream extrusion head 6, as they can occur due to
the
reaction pressure, are avoided.
CA 02449733 2003-12-O1
13
A spontaneous exothermic reaction in the extrusion solution 2, for example,
occurs
when a certain temperature is exceeded or in case of an ageing of the
extrusion so-
lution 2, particularly in dead water zones. In order to avoid the occurrence
of dead
water zones and burblings and to ensure a uniform flow of the extrusion
solution
through the line system 4, the line system 4 is formed so as to enhance flows
in the
overall region through which the highly viscous extrusion solution flows.
In the extrusion head 6, the extrusion solution is distributed to a plurality
of extrusion
ducts 8 in the form of spinning capillaries in a nozzle space 7. The spinning
capillar-
_ ies 8 are arranged in line, in Fig. 1 perpendicularly to the plane of
projection. By
means of a single extrusion head 6, thus a plurality of continuous moulded
products
is prepared simultaneously. Moreover, a plurality of extrusion heads 6, each
forming
a plurality of continuous moulded products or, in case of the embodiment of
Fig. 1,
filaments, can also be provided. In Fig. 1, only one spinning capillary 8 is
shown for
the sake of simplicity.
Normally, the spinning capillary has an internal diameter D of less than 500
p.m, for
special applications, the diameter can also be less than 100 Vim, preferably
about 50
to 70 pm.
The length L of the spinning capillary through which the extrusion solution
flows, is at
least twice the internal diameter D, maximally 100 to 150 times the internal
diameter
D.
The spinning capillary 8 is at least sectionwise surrounded by a heating means
9 by
which the wall temperature of the spinning capillary 8 can be controlled. The
wall
temperature of the spinning capillary 8 is in operation about 150°C.
The temperature
of the spinning solution is in operation between about 80 and 130°C.
The spinning
capillaries 8 can also be disposed in an arbitrary form in a carrier body, the
tem-
perature of which is controlled from the outside, so that the hole densities
in the ex-
trusion head 6 are high.
CA 02449733 2003-12-O1
14
The heating means 9 preferably extends to the outlet 10 of the extrusion duct
situ-
ated in the flow direction S. Thereby, the wall of the extrusion duct 8 is
heated down
to the extrusion duct opening 10.
Due to the direct or indirect heating of the extrusion duct, at the internal
wall thereof
and due to the viscosity of the extrusion solution depending on the
temperature, a
heated film flow having a low viscosity as compared with the central flow is
formed.
Thereby, the velocity profile of the extrusion solution within the extrusion
duct 8 and
the extrusion process are positively changed such that an improved loop
stability and
a reduced fibrillation tendency of the extruded spinning solution are
achieved.
In the extrusion duct 8, the extrusion solution is extruded and subsequently
exits in
the form of a filament 11 in an air gap 12. In the flow direction S of the
extrusion so-
lution, the air gap has a height H.
In the air gap 12, air 13 is supplied at a high velocity to the extrusion
solution from
the extrusion head 6. The flow direction can be guided horizontally up to the
extru-
sion filament; the flow velocity of the air 13 can be higher than the
extrusion velocity
of the filament at which the continuous moulded product exits the extrusion
duct
opening 10. Due to an air flow which is essentially guided coaxially, a
tensile stress
acts at the boundary surface between the continuous moulded product 11 and the
air
13, which stress can draw the continuous moulded product 11.
After having passed the air gap 12, the continuous moulded product enters a
coagu-
lation bath zone 14 where it is wetted or moistened with a coagulation
solution. The
wetting can either be effected by means of a spraying or moistening device
(not
shown) or by immersing the continuous moulded product 11 in the coagulation
bath.
Due to the coagulation bath solution, the extrusion solution is stabilized.
A further possibility is to deposit the continuous moulded product 11
essentially with-
out tensile stresses downstream of the coagulation bath zone 14 on a conveyor
means 15. The conveyor means 15 is equipped as a vibrating conveyor. Due to
the
CA 02449733 2003-12-O1
to-and-fro movement of the vibrating conveyor 16, the continuous filaments are
de-
posited on the conveyor means in straightened staples 17. Due to the
conveyance on
the conveyor means 15 without tensile stresses, the continuous moulded product
11
can stabilize without detrimental effects acting on the mechanical
characteristics of
5 the continuous moulded product 11, as they can, for example, occur by a
premature
mechanical load shortly after the extrusion of the continuous moulded product
11.
Depending on the design, the continuous moulded product 11 is drawn off by
means
of a draw-off work 18 upstream or downstream of the conveyor means 15 and sup-
10 plied to a cutting machine 20 via deflection or conveyor means 19. Via the
draw-off
work 18, the corresponding fibre parameters, such as titer, stability and
stretching,
are regulated.
The continuous moulded products 11 only of a part of the extrusion heads 6 or
of all
15 extrusion heads 6 are introduced into the cutting machine 20 in parallel.
In the cutting
machine 20, there is positioned a pair of rolls (not shown) for supplying the
continu-
ous moulded product bundles 11 of the various extrusion heads 6 to the cutting
ap-
paratus, the actual cutting apparatus (not shown) and a staple fibre washing-
down
device. The cutting apparatus (not shown) draws the tow fed by the pair of
draw-off
rolls by means of a water jet injector to horizontally rotating cutting
knives.
By means of the cutting knives, the fibre mass is cut to a predetermined
length. The
cutting knives maintain their edge retention during the cutting process by a
continu-
ous regrinding. By the water jet supply, a first dissolution of the staple
fibre stacks
formed during the cutting process is effected before the suspension of the
staple fibre
stacks to form a fibre mass.
An essentially mat-like fibre mass 21 exits from the cutting machine 21, which
mass,
together with the water supplied during the cutting operation, is washed into
a device
22 for treating the fibre mass 21. The fibre mass 21 is formed by a random
orienta-
tion of the fibres cut in the cutting machine 20.
CA 02449733 2003-12-O1
16
The device 22 for treating the fibre mass 21 essentially constitutes the
subject matter
of the present invention.
In the device 22, treatment steps typical of viscose fibres are accomplished,
such as
deacidification, desulphurization, washing, bleaching and washing,
antichlorine
treatment, washing with water as well as applying an avivagelfat coating or
other
chemicals. The individual treatment steps or phases, respectively, each take
place in
treatment zones 23, 24, 25, 26, 27, which are separated from one another by
press-
roll arrangements 28, 29, 30, 31, 32, 33. In each treatment zone 23 to 27, via
an im-
pregnation means 34, 35, 36, 37, 38 a treatment fluid each associated to this
treat-
ment zone or treatment step, respectively, is fed from corresponding
reservoirs 39,
40, 41, 42, 43. The treatment zones have a distance of at least about 0.5 m
from roll
center to roll center in the conveying direction of the fibre masses, however,
the dis-
tance can be up to 10 m and more depending on the requirement of the treatment
I 5 operation. In an extreme case, the individual press-roll arrangements 28,
29, 30, 31,
32, 33 can, however, also directly follow one another, so that the press-rolls
just do
not contact.
In the process, the reservoirs 39 to 43 are provided with treatment fluid in a
reverse
flow, i.e. the treatment fluid from a consecutive step in the conveying
direction B of
the fibre mass 21 is fed to an upstream treatment step in the treatment
direction es-
sentiaily without being cleaned; the direction of the flow of the treatment
fluid through
the device 22 is opposite to the conveying direction of the fibre mass 21
through the
device 22. In the conveying direction B, consequently the purity of the
treatment fluid
in the reservoirs 39 to 43, which are disposed as collecting vessel below the
fibre
mass 21, is increased. The fibre mass 21 is conveyed by the device 22 on a con-
veyor means 44 which can be designed as endless travelling screen or an
endless
wire-cloth belt, an oscillating conveyor or an eccentric notched conveyor.
The press-roll arrangements 28 to 33 can be designed either, as shown in Fig.
1, as
paired rolls or as individual rolls with a fixed counterpressure face. The
force of the
pressure of the rolls can be generated electrically, hydraulically or
pneumatically as
CA 02449733 2003-12-O1
17
well as mechanically, for example by means of leverages. The typical force of
pres-
sure of the press-roll is up to approximately 100 N per mm of the roll width.
Due to the pressing power exerted by the press-roll arrangements 28 to 33, the
treatment fluid introduced into the respective treatment zone 23 to 27 is
pressed out
of the fibre mass and the treatment fluid is prevented from being carried away
from a
previous treatment step to the next treatment step.
After having passed the device 22, the fibre mass 21 can be fed to further
treatment
steps not shown in Fig. 1. For example, a drying device with opening
aggregates for
dehumidifying and relaxing the fibre mass and consecutively a packaging
aggregate
for manufacturing a product ready for shipping can follow.
Fig. 1 shows an example of the preparation of a fibre mass from a spinning
solution
containing cellulose. However, the use of the device 22 is not restricted to
cellulose
fibres but can be also used for nonwoven-like or woven fibre masses of
filaments of
other compositions. For preparing such fibre masses of non-viscous or non-
cellulosic
fibres, other manufacturing methods are known from the prior art.
In the foNowing, one press-roll arrangement each is described by way of
example. As
the basic function of the press-roll arrangements 28 to 33 is the same in each
case,
in the following description only one single press-roll arrangement is
discussed by
way of example.
Fig. 2 shows a first embodiment of a press-roll arrangement 50 according to
the in-
vention for treating the fibre mass 21 in a section perpendicular to the
moving direc-
tion B of the fibre mass 21.
The press-roll arrangement shown in Fig. 2 is used for washing the tow or the
staple
fibres with low speeds and large fibre masses, the fibre mass being moved at a
speed of approximately 40 m/min in the conveying direction. This speed
corresponds
to the extrusion rate of the continuous moulded products at the extrusion
head. With
a basis weight of the fibre mass of 0.1 kg/m2 when absolutely dry, the fibre
through-
CA 02449733 2003-12-O1
Ig
put is approx. 52 kg/(mZh), the treatment fluid being fed at a flow rate of
125 m3l(h m)
per m of the roll width.
The press-roll arrangement 50 comprises a press-roll 51 which is rotatably
mounted
in a bearing not shown in Fig. 2 and rotates along with the motion of the
fibre mass
21 in the direction of the arrow P. The press-roll 51 is pressed into the
fibre mass 21
with a force of pressure F. In the process, a pressing surface area 52 which
is the
idealized enveloping surface about the press-roll 51 by which the pressing
power
generated by the force of pressure F acts on the fibre mass 21, is formed.
The region across which the force of pressure F acts as pressing power on the
fibre
mass 21 via the pressing surface area 52 is designated as pressing zone 53. In
the
moving direction B of the fibre mass 21, in the pressing zone first of all the
pressing
power is increased up to approximatley the region where the press-roll 51
maximally
IS penetrates the fibre mass 21. The region of the pressing power increasing
in the
moving direction B of the fibre mass is hereinafter referred to as compression
region
54. Following the compression region 54 in the moving direction B of the fibre
mass
21 is an expansion region 55 where the pressing power is again reduced in the
moving direction B of the fibre mass.
In the compression zone 54, due to the increased pressing power the treatment
fluid
56 taken up in the fibre mass 21 is pressed out, so that following the
compression
zone 54 nearly no more treatment fluid 56 from the previous treatment step is
pre-
sent in the fibre mass 21.
In the embodiment of Fig. 2, the press-roll 51 is provided with passages 57
which
extend from the inside of the press-roll to the outside of the press-roll. At
the outer
peripheral surface 59 of the press-roll 51, the passages 57 end in recesses
58, the
diameter of which is larger than the diameter of the passages 57. The passages
can
also be attached slit-like along the press-roll axis and be correspondingly
distributed
across the periphery.
The diameter of the bores is 3 to 12 mm with a roll diameter of 400 mm. The
opening
CA 02449733 2003-12-O1
19
degree of the press-roll 51 is approximately 5 to 40%, largely independent of
its di-
ameter.
The through bores 57 can be distributed arbitrarily, in rows in the axial
direction or in
the peripheral direction or set off relative to one another at the outer
peripheral sur-
face 59.
In the embodiment of Fig. 2, the inside of the press-roll forms a part of the
impregna-
tion means through which treatment fluid is introduced into the fibre mass.
Inside the press-roll 51, a cover body 60 is provided, which has an
essentially tubular
design and comprises an opening 61 extending in the axial direction of the
press-roll
51 in the form of a slit facing the pressing zone. The cover body 60 does not
move
along with the press-roll 51 but is stationary. At each of its ends facing the
slit, the
cover body 60 is provided with sealing elements 62, so that no treatment fluid
from
the interior space 63 of the press-roll 51 can come between the cover body 60
and
the internal peripheral surface 64 of the press-roll 51.
The cover body 60 serves for defining the region 65 via which treatment fluid
is intro-
duced into the fibre mass 21. The region 65 extends according to Fig. 2 mainly
into
the region of the expansion zone 55, but also - at least by sections - into
the region
of the compression zone 54. If treatment fluid, which can be, for example,
under a
pressure of 2.5 to 3 bar, is conducted from the interior space 63 of the press-
roll 51
through the passages 57, this treatment fluid will wash out the treatment
fluid 56 from
the previous treatment step in the compression zone 54, as schematically
indicated
in Fig. 2, and at the same time it will be absorbed in the expansion zone 55
by the
capillary action and the swelling of the fibre mass 21 due to the reducing
pressure.
As a result, a homogenous and fast distribution of the treatment fluid
supplied
through the press-roll 51 or the pressing surface area 52, respectively, is
achieved. in
order to be able to adjust the position of the slit 61 relatively to the
pressing zone 53,
the first cover body 60 is coaxially held in the press-roll 51 to be pivoted
about its
longitudinal axis X, as implied by the double arrow A.
CA 02449733 2003-12-O1
Fig. 3 shows a fiurther development of the embodiment of Fig. 2. Here, below
only the
differences to the embodiment of Fig. 2 are discussed.
5 The press-roll arrangement of Fig. 3 can, for example, be used for washing a
cellu-
lose nonwoven as fibre mass 21 having a weight of approximately 4.1 kg/m2. In
this
application, the fibre mass is moved in the conveying direction at a rate of
approx.
0.1 mlmin. The fibre throughput per m of the roll width is about 40 kgl(h m2)
with such
an application. The treatment fluid is supplied with a throughput of 0.7 m31(h
m).
In contrast to the one-piece cover body 60 of Fig. 2, the cover body is
divided into
two cover bodies 60a and 60b in the further development of Fig. 3. Each of the
two
cover bodies 60a, 60b is held independently of the other cover body at the
inner pe-
ripheral surface 64 of the press-roll 51 to be pivoted about the longitudinal
axis
thereof. Thus, in the press-roll arrangement 50 according to Fig. 3, the
opening angle
oc as well as the orientation of the slit 61 can be changed by adjusting one
of the
cover bodies 60a, 60b or both cover bodies 60a, 60b. In order to seal the
interior
space 63 of the press-roll 51 outside the slit region, a sealing body 66 is
provided
which covers a moving slit 67 which is also formed by the two cover bodies
60a, 60b
and ensures the movability of the two cover bodies 60a, 60b relative to one
another.
The sealing body 66 can be arranged within the cover bodies 60a, 60b or, in an
al-
ternative embodiment, between the cover body 60a, 60b and the press-roll 51.
At its
ends, the tubular sealing body 66 provided with a longitudinal slit is
provided with
sealing elements 68 which avoid the penetration of treatment fluid between the
cover
body and the sealing body.
In the embodiment of Fig. 3, due to the high variability with respect to the
size and
position of the treatment zone 65, an exact adaptation to the respective
treatment
step and the moistening requirements of the treatment fluid fed into this
treatment
step can be effected.
In phantom lines, for example a one-sided adjustment of the left cover body
60b is
CA 02449733 2003-12-O1
21
shown in Fig. 3, resulting in a treatment zone 65 being only situated in the
expansion
region 55, through which the treatment fluid is introduced into the fibre mass
21.
A second embodiment of a press-roll arrangement according to the invention is
rep-
resented in Fig. 4. Here, for elements the design or function of which
essentially cor-
respond to the elements of the previous embodiment, the same reference
numerals
are used.
In the embodiment of Fig. 4, the press-roll 51 is formed of a plurality of
ribs 70 ex-
tending in the axial direction X of the press-roll 51. The ribs have a wall
thickness
which increases in the radial direction from the inside of the press-roll 51
to the out-
side. At their outer side, the ribs 70 at least by sections form the pressing
surface
area 52 in the pressing zone 53. The ribs 70 are each fixed at mounting plates
or
rings at the two ends of the pressing surface area positioned in the axial
direction X.
I S The ribs 70 all extend in parallel to one another and are equally spaced
apart from
one another, the region 71 between them is essentially free of materials. The
ribs 70
can be interconnected by plate- or ring-like struts extending in the
peripheral direc-
tion, so that they obtain a higher mechanical stability.
In the embodiment represented in Fig. 4, the opening degree of the press-roll
40 can
be in individual cases up to between 90 and 95%. The number of ribs is between
30
and 80, preferably about 60. With a diameter of the press-roll of 400 mm, the
width of
the rib can be between 1 and 20 mm in the peripheral direction, using broader
struts
leads to a higher pressure, but a lower flow rate.
In the interior space 63 of the press-roll 51, an impregnation device 72 is
arranged,
through which treatment fluid is guided into the interior space 63 of the
press-roll 51.
Such an impregnation means 72 can for example alternatively also be used in
the
embodiment of Fig. 2 instead of or together with the cover body 60.
Inversely, the impregnation means can also be used according to the embodiment
of
Fig. 2 or 3 together with the cover body 60 described therein.
CA 02449733 2003-12-O1
22
The impregnation means 72 of the embodiment of Fig. 4 consists of a central
supply
line 73 extending coaxially to the axis X of the press-roll 51. The supply
line 73 is rep-
resented in Fig. 4 cut at its end positioned in the axial direction X,
however, at its
right end in Fig. 4, an end cap can be provided, or the supply line 73 can
extend
through all of the press-roll 51 in the axial direction X and supply the
treatment fluid
to a further press-roll arrangement. The end of the supply line 73 in the flow
direction
S of the treatment fluid can be connected with the inlet of the supply line 73
in order
to make possible a recycling of the treatment fluid in this treatment step.
The impregnation means 72 is further provided with one or a plurality of spray
noz-
zles 74 which are directed to the fibre mass 21. The treatment fluid flows
from the
central supply line or the collective tube 73 through the individual nozzles
74 and
between the ribs 70 into the fibre mass 21.
Fig. 5 shows a section perpendicular to the axial direction X of the
embodiment of
Fig. 4.
In Fig. 5, one can see that the treatment fluid from each of the spray nozzles
74
forms an atomizing cone 75, the atomizing cones 75 overlapping such that in
the
pressing zone 53 there is no region which is not moistened by the treatment
fluid.
The atomizing cones 75 can be conical or even.
In order to prevent the treatment fluid 56 from being carried away into the
region
situated downstream of the pressing zone 53 in the moving direction B of the
fibre
mass 21, the height H of each rib 70 is dimensioned such that the ribs
essentially
situated in the pressing zone 53 form a weir through which a direct flow of
the treat-
ment fluid between the regions at both sides of the pressing zone is not
possible.
As by the rotation D of the press-roll 51 treatment fluid could be conveyed
from one
treatment step to the next treatment step through the space 71 between two
ribs 70,
a spraying nozzle 74' is directed to the compression zone in order to wash out
treat-
CA 02449733 2003-12-O1
23
ment fluid 56 possibly flowing in from the previous treatment step.
Via a regulation means 76, for example by the spraying nozzles 74 being
attached to
tubes 76 rotatable relative to one another and being concentric to the supply
line 73,
the treatment region 65 can be regulated with respect to size and orientation
by ad-
justing the spray nozzles 74.
The distance between the ribs in the peripheral direction is dimensioned such
that a
sufficient amount of treatment fluid can pass between the ribs and at the same
time
the pressing power in the pressing zone 53 can still uniformly act on the
fibre mass
21.
Fig. 6 shows a perspective view of a third embodiment of a press-roll
arrangement 50
according to the invention. Here, for elements the design and function of
which cor-
I S respond to an element of the previous embodiments, the same reference
numerals
are used as in the previous embodiments.
The press-roll 51 of the embodiment of Fig. 6 comprises ribs 70 spaced apart
in the
axial direction X of the press-roll 51 between which a space 71 is formed.
The press-roll arrangement 50 further comprises two impregnation means 72a,
72b,
which are arranged at both sides of the press-roll 51 with respect to the
moving di-
rection B of the fibre mass not shown in Fig. 6 for the sake of simplicity.
Each impregnation means 72a, 72b comprises a collective tube 73 extending in
par-
allel to the axial direction X of the press-roll 51 from which supply lines 80
extend into
the spaces 71 between the ribs 70 down into the pressing zone 53.
In the embodiment of Fig. 6, the supply lines 80 of the two impregnation means
72a
and 72b are interconnected in one piece, so that the treatment fluid from the
collec-
tive tube 73 of the impregnation means 72a flows to the collective tube 73 of
the im-
pregnation means 72b and a part of the treatment fluid exits in the pressing
zone 53
through openings of the supply lines 80 not shown in Fig. 6.
CA 02449733 2003-12-O1
24
Alternatively, the supply lines 80 of the impregnation means 72a and the
supply fines
80 of the impregnations means 72b can be separated, so that through the
impregna-
tion means 72a another treatment fluid than through the treatment means 72b is
in-
troduced into the pressing zone 53. This enables a higher variability and
adaptability
of the treatment to be carried out by the press-roll arrangement 50 with
various fibre
masses and treatment fluids.
The cross-section of the supply lines 80 is designed such that it essentially
corre-
sponds to the cross-section of the spaces 71 and thus largely fills the spaces
71. The
flow S of the treatment fluid through the collective tube 73 is conducted
through the
supply lines 80 into the pressing zone 53. This can be in particular seen in
Fig. 7,
where a front view of the embodiment of Fig. 6 is shown in the moving
direction B of
the fibre mass 21.
In Fig. 7, a supply line is shown as partial section in the region of the
pressing zone,
in particular in the region of the expansion region 55.
The supply line comprises openings 81 in this region, through which the
treatment
fluid exits into the space 71 and enters the fibre mass 21 through the
pressing sur-
face area 52.
Alternatively to the representation in Fig. 7, the section of the supply lines
80 facing
the fibre mass 21 can also come into contact with the fibre mass 21. In this
case,
however, special arrangements with respect to the surface quality and the
abrasion
resistance of the supply lines 80 have to be taken in order to avoid a damage
of the
fibre mass 21 and a premature wear of the supply lines 80 by the fibre mass 21
being
passed under pressure.
In an alternative design of the embodiment of Figs. 6 and 7, the impregnation
means
72a being in front with respect to the moving direction B of the fibre mass 21
can also
be designed as a suction means by which treatment fluid is sucked off for
example
from the compression region via the openings 81 in the supply lines 80.
CA 02449733 2003-12-O1
In Fig. 7, furthermore a driving means 82, for example an electric motor, is
repre-
sented, by which the press-roll 51 is rotatably driven synchronously with the
motion
of the fibre mass. Such a driving means 82 can also be used with other embodi-
5 ments. In this design, the press-roll itself can be employed as conveyor
means for
the fibre mass 21, by which the fibre mass 21 is transported through the
individual
treatment steps of the pressing mill.
Fig. 8 shows a fourth embodiment of a press-roll arrangement 50 according to
the
10 invention in a section in parallel to the moving direction B of the fibre
mass 21 and
perpendicular to the axial direction X of the press-roll 51. The press-roll
arrangement
50 according to Fig. 8 comprises a counterpressure roll 90 which is pressed
into the
fibre mass 21 with a force of pressure F2 opposite to the press-roll's 51
force of pres-
sure F~ having the same value. The press-roll 51 and the counterpressure roll
90
15 both comprise the same configuration which corresponds to the configuration
of the
first embodiment as represented in Figs. 2 and 3.
For the sake of simplicity, for the embodiment of Fig. 8 therefore for
elements, the
construction and function of which correspond to previous embodiments, the
same
20 reference numerals are used.
In the embodiment of Fig. 8, in the expansion region 54 the treatment fluid is
sucked
off from the previous treatment step by the counterpressure roll 90, as
schematically
shown by the arrow S~, while in the expansion region 55 treatment fluid for
the next
25 treatment step is conducted through the press-roll 52 into the fibre mass,
as indicated
by the arrow S2.
Alternatively to this embodiment, each roll 51, 90 can effect a removal by
suction as
well as an impregnation in the pressing zone 53.
As represented in Fig. 1 by means of the device 22, when using the press-roll
ar-
rangement 50 according to the invention in a pressing mill 22, the press-roll
ar-
rangement for the next treatment step can directly follow, as due to the
imprEgnation
CA 02449733 2003-12-O1
26
of the fibre mass 21 through the pressing surtace area 52, an immediate homoge-
nous distribution of the treatment fluid in the fibre mass 21 is effected.
Thereby, the overall length of the pressing and treatment device 22 is
considerably
reduced.
Due to the immediate homogenous distribution within the fibre mass 21, which
is
supported by the short fibre distance in the expansion zone 55 and the
resulting cap-
illary effect, the impregnation process can be accomplished more precisely and
be
controlled more easily. As a result, even an impregnation with treatment
fluids to be
handled carefully, which possibly tend to react chemically, is possible.
The rolls according to the invention can also be employed at other locations
of a
plant for manufacturing fibres, for example as draw-off rolls with integrated
waxing
I S means.
Apart from the fibre mass of cellulose described by way of example, fibre
masses of
natural or synthetic fibres can also be treated by the device according to the
inven-
tion and the method according to the invention, for example fibre masses of
viscose,
acetate, polyester, polyamide and polyacryl.
Below, special examples for further illustrating the above-mentioned
embodiments
are given m a table.
In the examples 1 to 4 of the following table, a fibre tow manufactured
according to
the Lyocell-method is brought into a staple shape by means of a wet cutting
machine
and in this condition applied on a treatment device 22 as fibre mass 21.
Concerning
the indications of weight, the fibre mass in an absolutely dry condition is
taken as a
basis. In example 5, the fibre tow is supplied to the treatment device 22 as
fibre mass
21 directly without cutting it beforehand. As treatment fluid, water is used
in all exam-
ples. The device 22 is in all examples 1 to 5 designed such that in every
treatment
zone the fibre mass 21 is completely penetrated by the treatment fluid across
its
whole thickness.
CA 02449733 2003-12-O1
27
Exam 1e 1 2 3 ~~ 4 5
Impregnation Spraying Roll Roll Roll Roll
b means
of
T a of Fi . Fi . Fi . Fi , 2
roll 4 4 2
Condition Sta 1e Sta 1e Sta 1e Sta 1e Tow
Line pres-Nlmm 12 12 10 10 10
sure per
mm
of the
press-
roll width
Fibre masskglmZ 7,2 7,2 3,1 4,1 0,1
per mZ
area
of the
treat-
ment zone
Washing m/min 1,5 1,5 0,3 0,1 36
s eed
Liquid m~lhm 15,4 15,4 2,5 0,7 125
throughput
per metre
of
the roll
width
Fibre kglm2h 324,8 1299,4 93,8 41,3 51,6
throughput
per m2
of the
treatment
zone
In example 1, the impregnation of the fibre mass is effected according to the
method
from the prior art by spraying the treatment fluid onto the fibre mass in the
conveying
direction downstream of the press-roll. In this method, the fibre mass 21 is
not com-
,~ pletely penetrated immediately after the contact with the treatment fluid,
so that the
treatment fluid accumulates like a lake above the fibre mass and only
gradually
trickles through the fibre mass 21. This formation of a lake is increased as
the thick-
ness of the fibre mass is increased. A complete penetration of the fibre mass
with the
treatment fluid is only achieved after a relatively long dwell time of the
fibre mass in
the treatment zone. To this end, the treatment zone has to comprise a
corresponding
length in the conveying direction of the fibre mass through the treatment
device.
In example 2, the treatment is in contrast accomplished with a press-roll
designed
according to the invention with treatment conditions otherwise identical to
example 1.
As can be seen from the table when comparing examples 1 and 2, in example 1,
i.e.
CA 02449733 2003-12-O1
28
the solution of the prior art, the fibre throughput per m2 of the treatment
zone and per
hour is considerably lower than in example 2.
In the examples 3 to 5, the press-rolls according to the invention are also
used, so
that the fibre mass is immediately penetrated when contacted by the liquid and
long
treatment fields for the complete penetration of the fibre mass are not
necessary.
Moreover, in these embodiments an essentially more uniform and faster
distribution
of the treatment fluid in the fibre mass are the consequence.
