Note: Descriptions are shown in the official language in which they were submitted.
~1~1175
YI~G ORIENTED ~IB~O~S WEBS
~ his invention relates to the production of fibrous
webs having a high degree of orientation of the fibrous strands
comprisingaweb,comprising forwarding a strand towards a
collecting surface and imparting an oscillatory motion to
the strand at a point above the collecting surface.
Fibrous webs have been made from staple fibres
by caxding or by random air la~ing processes, the former
process imparting some degree of i~otropic arrangement of
the fibres. ~ibrous webs have also been made by collecting
a mat of synthetiG continuous filaments in which the filaments
are more or less randomly intermingled in the mat. However
in order that a fabric made from one or more webs should have
properties which resemble more closely the properties of
Gonventional woven or knitted fabrics it is considered desirable
to introduce a high degree of orientation of the fibrous
material Gomposing a web, as for example, a high degree of
parallelism in staple fibre yarns or filamentary strands
oriented in for example, the machine or cross direGtions or
2Q in both these directions. Methods which have been proposed
for introduoing the desired orientation into a web of
filamenta~y strands include those in which the extruded
multifilamentary strands are forwarded and drawn by means of
air jet: and the s9uir.g filaments are given an oscillatory
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motion before ~reely ~alling onto a collecting brautice
or supportO ~ specification 1 244 753 describes such
a method wherein gas oscillating jets are supplied with
already drawn filaments. It has also been proposed in
Japanese patent publication 75 007 178 to oscillate the
outlet of the forwarding jet to impart the desired
oscillatory motion to the emerging filaments. The prior
methods have not in practice proved entirely satisfactory
i~ producing webs of as high a degree of parallelism and
order as desi~ed. ~hus it is an object of this invention
to provide a method in which movement of a strand in the
laying down of a web iR more fully controlled so as to
approach more nearly the deqired high degree of parallelism
and order.
Thus by the present invention we provide a process
for the production Gf an ordered web from at least one
fibrous strand, comprising forwarding a strand towards a
collecting surface, imparting an oscillatory motion to
the strand at a point above the collecting surface,
characterised in that the oscillating strand is pas3ed
between two closely spaced plates which are substantially paral-
lel to each other and to the plane of strand oscillation and which
extend qubstantially from t~e place of oscillation down to the
collecting surface whereon the strand i9 laid substantially
parallel to the preceding lengths of the strand.
A180 according to the invention appa~atus for laying
down a fibrous strand in substantially parallel courses
comprises means for supplying a fibrous strand, means for
forwarding the strand, means to impart an oscillatory motion
to the forwarded strand and a collecting surface whereon the
i
~ ~ 30 strand is laid, characterised in that the apparatus includes
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~1C11175
two closely spaced plates which are substantially parallel to
each other and to the plane of oscillation and which extend
between the oscillating means and the collecting surface.
It is preferred to use a continuous filamentary
strand in the present invention since these may be
produced directly from a synthetic poly,meric substance as
for example by melt spinning. Staple fibre strands,
preferably having only a low degree of twist, may also be
used and the term 1'fibrous strand" as used herein includes
- 10 both these and similar materials.
In producing a multifilament y strand by melt
extrusion of a synthetic polymer it is desirable to draw
or orient the filaments to improve their strength and
other physical properties. ~his may be done by forwarding the
freshly extruded filaments at a high speed such that when
they ha~e cooled sufficiently any further drawing down of
the ~till plastic filaments will cause orientation and
alignment of the polymer chains which is set in on further
cooling of the filaments to a temperature below the glass
transition point. A gas forwarding jet i9 a convenient means
to forward the strand and to produce this orientation.
Means to impart an osoillatory motion to the strand may also
utilise a compressed gas. ~hus jets may be located on opposite
sides of the forwarding jet outlet and operated alternately
80 as to direct the issuing strand first in one direction and
then in the opposite direction. Alternatively a single
intermittently operated jet may be used to impart the
oscillatory motion.
A single or two port rotary valve may be
3 conveniently used to provide the alternate or intermittent
operation of the two jets or the single jet and the speed of
rotation of this valve p~ovides a simple control over the
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llQ1175
amplitude of oscillation described by the strand; the
rotation speed bearing an inverse relationship to the
strand amplitude when other conditions are constant.
Thus the length of the courses of the strand laid on the
collecting surface may be set within at least the range
0.5 - 4 m by adjustment of rotary valve speed
particularly because the use of closely spaced plates
between the oscillating jets a~d the collecting surface
allows changes to have their full effect on strand
movement. Oscillating jets may have a single orifice or
number of orifice3 in line or preferably a narrow slot
for exit of the compressed gas. It is preferred to mount
the deflecting jets so that both the angle between the
jets, if two are used,and the angle of the or each jet
in relation to the issuing strand may be adjusted as a
further means of controlling strand oscillation.
While deflecting gas ~ets are preferred, other
device3 may be used to impart oscillation to a strand
provided they can induce a sufficiently large amplitude of
oscillation at the collecting surface. Such alternative
devices may be rotating or oscillating opposed pairs of
coanda surface~ which are alternately brought into contact
with the issuing 3trand.
~orwarding jets are well known in the art
consisting of ent~y and exit passages for the strand and means
to introduce the forwarding gas. The exit passage may be
convergent or divergent but it is preferred to use a parallal
passaga to maintain the integrity of the issuing strand
passing to the place of oscillation.
~0 We have found that when closely spaced platas
~e proviaed between the forwarding/oscillating mPans and the
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llQ117S
collecting surface the strand will assume a pIanar wave
form oscillation the amplitude of ~hich may increase in
successive half waves from the place of oscillation up to
a value dependent upon the forces involved and will maintain
this planar motion until it reaches the collecting surface
whereon it is laid in substantially parallel regular courses.
It i3 preferred that the height of the plates above ths
collecting surface is about the same as the distance required
to establish the first crest in the waveform oscillation
or the maximum amplitude if an oscillation of this kind
is established. ~he plates should extend as close to the
place of oscillation and as close to the collecting surface as
is practicable 80 that maximum control of the falling strand
is maintained.
The method and apparatus of this invention make
it possible to lay highly oriented webs in which the
strands are laid in parallel courses with an exactitude
and precision hitherto impossible. A measure of this
exactitude or efficiency may be defined as follows:-
Efficiency E = Actual web width ~m)
Length of strand/course (m)
The denominator may be expressed as:-
strand s~eed at ~oint of oscillatio ~ m/min)
20strand oscillation rate (cycles/min)
~hus E (%) may be expressed as:-
E = 2 W R 100S
where E is the percentage laying efficiency
W is the actual web width in metres
R is the oscillation rate, cycles/min
and S is the strand speed at oscillation (or issue from the
forwarding means)in m/min.
Strand laying efficiency defined in this way is an
overall measure of effectiveness and for example in laying webs
- of continuous synthetic filamentary yarns values of 95% and
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better are attained and in these webs for all but a few
percent of web width at the edges the efficiency i8
substantially 100%.
~se of this invention is particularly beneficial
in the laying of such highly parallel webs of widths
in excess of 0.5 m and at high strand speeds. Thus webs
of 2.5 m width may be laid at a strand speed of at least
3600 m/min with an overall efficiency of 96% or more.
In addition the laying of each course may be conducted with
a very high precision to produce a web of substantially
uniform thickness particularly when several strand laying
devices are to be used together to produce a single or
multi-layer web.
It i9 preferred to produce webs by moving the
collecting surface away from the laying position at a speed
related to the speed of strand laying in a direction either
transverse to or parallel to the direction of laying. The
former direction produces a web with transverse strand
courses analgous to the weft of a woven fabric, ~he latter
direction, when the strand laying devioe(s) is reciprocated
transversely, produces successive bands of what may be termed
warp wise strand courses. A plurality of laying devices may be
used to lay webs having one or more layers of warp-and weft-
wiæe strand courses thNs leading to a final web exhibiting two
; 25 directional properties desirable in fabrics for use as ~ppP~el textlles. ~ ~
Webs made according to this invention require to be
bonded in some manner to convert them into u3eful fabrics and
for this purpose it is preferred to use some form of segmental
or spot bonding method so as to preserve the directional
properties introduced in making the web. It i3 ~urther
preferred to inolude m th~ web at leaet a proportlon
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175
of thermoplastic filaments or fibres and to employ a thermal
segmental bonding method for making the final fabric.
Such segmental bonding methods are described in for example
~nited Kingdom patent specifications 1 245 088, 1 474 101
and 1 474 1020 ~hermoplastic synthetic filaments ox
fibres of many kinds are suitable for use in this invention
either alone or in admixture with natural or other non-
thermoplastic fibres. It is most preferred that the webs
include or are composed of bicomponent synthetic fibres
in which one of the components present at least in part
at the surface of the fibre or filament is of lower softening
or melting point, than the other and forms a strong bond
under suitable conditions of heat and pressure. Alternatively
or in addition to the foregoing segmental or spot bonding
methods other processes may be used as for example, stitch
bonding in which the web is held together by chains of
stitching using a separate thread or part of the web itself
and machinery which is capable of operating at fast production
rates.
Synthetic polymeric filamentary strands being non-
; conductors and hydrophobic tend to accumulate static charges when
in frictional contact with processing surfaces and as such
charges may disturb the even oscillation or laying of a falling
strand care is necessary to eliminate or reduce the accumulation
of such charges by the provision of static discnarging means
at or near the point of oscillation or by surface treatment
of the filaments with an appropriæte chemical agent.
It is preferred, when using a gas forwarding jet,
that a small amount of the issuing gas is allowed to pass in
a gentle current down between the plates to assist the passage
of an oscillating strand down to the collecting surface.
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It is also preferred that the collecting surface is a
pe~vious brattice to allow escape of gas and if necessary
the application of suction to the under side at the place
of contact with a newly laid strand and thu,s to ensure
its co~plete contact with the brattice.
The accompanying drawings illustrate the invention
and one manner in which it may be performed using compressed
gas both for transport and for oscillation of a strand.
~ ig 1 is a front elevation of apparatus in which
a strand is being laid transversely onto a foraminous
oonveyor and
~ig 2 i9 a side elevation of the apparatus of ~ig 1.
Referring to ~ig 1 a s~rand 1 is led by way of a
small tension roll 2 into the entry 3 of a forwarding jet 4
which i8 supplied with compressed gas from a supply port 5
above the strand entry 3~ ~he gas tensions the yarn forwards
it to the outlet 6 clo~e to which on either side are positioned
deflection jets 7 which are alternately supplied with pulses
of gas from a motorised rotary valve 8. ~he strand 1 falls
~' 20 from the jet outlet 6 into the convergent entry 9 of two
p æallel plates 10 narrowly spa¢ed ap~rt and arranged
tran3versely and close to an endless foraminous co~veyor 11.
Gas jet~ 7 alternately are directed against the emerging
strand 1 moving it to the left and then to the ri~ht and
causing it to oscillate and to assume a planar sinu~us path
: as it falls between plates 10. As the strand 1 passes between
the plates 10 the initial motion imparted by the deflection
jets 7 develops to its ~ull extent until at the level of the
conveyor 11 the ~trand has moved out to the full desired width
and is then laid down on the conveyor in successive p æallel
: courses 12 acros~ the conYeyor. To a~sist the reg~lar and
complete laying of eaoh strand on the conv~yor an exhaust duct
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11~1175
13 is positioned bcneath the conveyor ll and is prov.ded
with a narrow slot inlet 14 arranged close to the underside
of the conveyor and immediately below the lower edges of
plates lO. A ~an 15 provides at the inlet 14 suction to
draw the strands against the conveyor surface.
In fig l left and right moving l~ngths of strand
l are shown moving in somewhat idealised fashion between
plates lO as solid and broken lines respectively. Exam-
ination of the apparatus illustrated in the drawings in the
operating condition by means of stroboscopic illumination
through a transparent plate lO shows that the strand takes up
a uniform sinuous path the form of which alters with changes
in forwarding and oscillating speeds.
The plates lO serve to control and stabilise the
movement of the oscillating strand. ~he width of the plates
in the direction of oscillation should be at least equal to
and is preferably just a little wider than the maximnm width
of web to be laid. As described above the height of the
plates depends upon the laying conditions used and the form
of the strand path established. The plates should be as
closely spaced as possible and preferably should taper slightly
in the downward direction as for example from a spacing at
the top of 4 mm to a spacing at the lower end of 2 mm. This
taper assists the sideways exhaust of air and reduces the
possible disturbance of strands on the collector. Likewise
the distance between the lower ends of the plates and the
collector is minimised consistent with maximising the efficiency
and precision of laying that is to say so as to give maximum
~; control of the strand while it is moving and immediately after it is laid. ~or higher strand speeds and web width3 the
functions of the plates become increasingly important.
In the absence of one or both plates even at low strand
speeds, narrow web ~ dths and the complete absence of
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11(~1175
extraneous influences such as air currents entirely
unsatisfactory irregular webs are formed.
The following Examples illustrate the invention
and the manner in which it may be performed.
EXAMP~E 1
A strand composed of 60 synthetic filaments
and with a final decitex of 200, spun direct from a
spinneret,; was led by way of rolls rotating at a speed
of 3650 m/min to the entry of a forwarding jet supplied
with compressed gas at a pressure of 1758 g/cm2 gauge.
A motorised rotary valve, supplied with compressed gas
at a pressure of 5625 g/cm2 gauge gave impulses of compressed
gas in turn to each of two deflector jets, fitted immediately
below the forwarding jet and symmetrically in relation
thereto at an included angle of 165 between the jets.
E~ch deflector jet receiving compressed gas from the rotary
valve ~or 50/0 of the valve revolution. The rotary valve
rotated at a speed of 2300 rpm. The strand emerging from
the forwarding/deflecting device was passed between a pair
of plates 0.9 m wide and 0.5 m high. The top of the plates
were l cm below the exit from the spray device and the plates
were spaced 4 mm apart at the top and 2.5 mm apart at the
bottom. The bottoms of the plates were 3 cm above a horizontally
dispo3ed foraminous conveyor. A suction slot, positioned
directly under the exit from the plates was in useO The total
strand width laid down was 0.74 m compared with a theoretical
width, calculated from the yarn and rotary valve speeds of
0.79 m, thus, giving an overall laying efficiency of 94%.
For most of the spray width, the filaments were laid with
30 substantially 100% parallelism the efficiency 109s occurring
in the 5 cm at eac~ edge where filaments diverged during the
threadline reversal.
11~117S
11
EXAMPLES 2- 5
Synthetic filamentary strands of various sizes
were laid into highly oriented webs with the same apparatus
as in Example 1 and the following processing parameters;
5 plate sizes being changed to suit the desired web width;
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SIRAND ~ORWAR~ VALVE PLATE
. ING JET S~PPLY VALVE DIMEM' 'IO~S(M)
~0 SPEED S~PPLY GAS SPFED
~ EM- ~ILS DTEX M/MIN PRGE/SCSM~-E ?RGE~ScSM~E (RPM) WIDT~ HElG~
GA~GE GA~GE
2 60 200 3550 2110 4218 1125 3.o o.75
3 60 200 3600 2110 5625 700 3.0 o.75
4 60 167 1735 2812 2460 445 3.0 0.75
120 400 ~650 2110 5976 2975 0.9 0.5
The webs were produced in the following widths
at the indicated overall efficiencies (ie including the edge
portions);
_ WEB WI3~TM) ~AYING
~ . ACT~AL ~ oRETIcAl EFFICIENCY
r 20 2 1.56 1.58 99
3 2.5 2.57 97
4 1.85 1.95 95
0.57 0.61 9~
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COMPARA~lv~ EXAMPLES A A~D ~
Webs were laid from the same filamentary strand as used
in Examples 2 and 3 and respectively (A and ~) with the same
processing parameters but in the absence of the plates, in an
environment substantially free from extraneous draughts and
other influences. ~he result3 were as follows:-
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1~1175
COMPA12AlIVE, WEB W:[D~I (M) :5, (/)
AC~AL I~EORE~ICAI . .
A 1.25 1-58 79
. 13 2.2 2.61* 84
5 * Forwarding speed ~650 m/min.
It was only possible to lay a narrower web under
these conditions and the laying efficiency was appreciably
reduced in both cases in the absence of plates.
l~XAMPLES 6
A web was laid from a synthetic filamentary strand
as used in Example 1 with similar apparatus differing only
in that the forwarding jet had a divergent exit passageway
instead of a parallel one. The other process parameters
and the results obtained were as follows:-
~FOEWARDl~E VALVE PL~l~E
: JEI~ SlJPP~Y SIJPPIY VALVE DI~SIO~S(~! DI~I(M) E~/~
EXA- PRES~ ; GAS SP~D . ~/J
MP~E GAGl/JClE~) PF(~G/CM2 (R~q) WIDI~ lIEIGEI~ AC~AL El!ICAL
_ GAIJGE) .
20 6 3~167 5976 2000 o,c 0. 5 0.70 0.~ ~7
me web laying efficiency is moderately high
but is not as good as with the forwarding jet of the preceding
Examples.
COMPARA~IVE E~A~LE C
For comparison a web waB prepared substantially
as described for EXample 6 but omitting the plates between
oscillating and collecting means with the following poor
results:-
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COMP ~OR~JARDING VALVE VALVE DL~IiA75A E WIM E~M--) E(~6)
MPLE PGAG/GME2E PRESSl~/ SPE D WID~ SEIGP.~ .~CT~AL ETICAI
C 2812 5976 2030 0.9 0. 5 0.61~ 0.9 76
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