Note: Descriptions are shown in the official language in which they were submitted.
~wos6l0s33s 219~759 r~",, c~,
APPARATUS AND METHOD FOR MAKING LOGS FROM HIGHLY
ORIENTED FLASH-SPUN CONTINUOUS FIBERS
Fiel~i of the Tnvention
The present invention generally relates to collecting highly
oriented flash-spun C~ bdchwillddble fibers from a spinneret in the
form of a rod-shaped batt, commonly referred to as a log.
B~rlc~olln-l ~nri S--mm~-y of the Tnvention
In the past, it has been desirable to collect flash-spun ~
fibers from a spinneret in the form of a rod-shaped batt, commonly hnown as
a log, wherein the fiber in the batt may be unwound from the end opposite
from which the fiber was fed into the batt. This is commonly referred to as
beingl,a~,hwil--l~ble. Forexample,U.S.Patents3,413,185;3,417,431;and
3,600,483 all disclose processes for forrning such logs. In brief, the process
for forming such logs generally comprises collecting the fiber from a
spinneret m a tubular shaped perforated collecting conduit. As the fiber
collects therein, it takes the shape of the conduit, i.e. a rod shaped batt. Thesolvent, which is ~ ,hr~ d from the spinneret with the polymer fiber, flash
ev.T and expands into the conduit cu~ hlg the fiber into the log,
pushing the log forward in the conduit, and escaping through the gas release
ports in the periphery of the conduit.
In the foregoing references, it should be noted that the spirmeret
does not include a tunnel at the exit thereof. As is disclosed in U.S. Patents
3,081,519 (Blades et al.) and 3,227,794 (Anderson et al.), a tunnel has a
gi nifir~nt effect on fiber tenacity. U.S. Patent 4,352,650 (Marshall)
discusses the u~,~i" . ,, ~ ,., of tunnel crnfi~l~tir,n for increasing fiber
tenacity from about 4.2 gpd to about 5.2 gpd, wherein fiber tenacity is
described as being increased by as much as 1.3 to 1.7 times by using an
a~J~lu~fl~lL~ly sized tunnel at the exit of the spinneret. Accu-~l~ ly, it wouldbe very desirable to use a tunnel and obtain higher tenacity fiber for the
rod-shaped batts.
However, when collecting the fiber into a log, it has long been
believed that the expanding jet of solvent vapor must be allowed to expand
fully and quickly so as to reduce or avoid the ~u~bul~,llcc that is created by
35 the high speed gases duwllall-,~ll of the spinneret. Such lUfl~ C tends to
I
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randomly collapse the fibers prior to the fibers being collected into the log,
and the fibers become di:~UI o~ ,d as they are collected. The fibers are
thereby sufficiently entangled to render the resulting log difficult to
bachwind. It is much preferable for the fiber to be collected while still in the5 expamded state so as to form a more organized log which is far easier to
backwind.
A further 7hUI ~;UIllillg of prior art logmahing methods is that
quite frequently, fibers 1 l l. .. "~ , - ily exit the gas release ports located along
the fiber collection tube with the expanding gas. This condition damages the
10 continuity of the plP~ifil~nnPnt~ry structure of the flash-spun fibers resulting
in more frequent filament brea~s during bal,hwi7ldillg of the flash-spun
fibers mahing up the log. Moreover, fibers exitmg the gas release ports
leave ~jl ll 1l i . .. ll .. .~ marks in the form of heavy axial ribs on the surface of the
resulting log. These axial ribs chamge the resistance of log motion through
15 the collection tube in am u~ cllil,Lallc manner. Due to this condition, logs
produced are not consistent in quality.
A further problem of prior art logmaking - .,."~. ."1 a~ is the
",- h~.~, ,1 gate at the collection tube exit for initiating the 1~ ~ g
process. The gate quite frequently catches fibers during start-up which
20 results in start-up failures and adds to the cost of ~lvdu~Livll.
Another problem with prior ,." ~ .g. .,~ is the mPrh:~nirsll
frictiûn element such as rubber gaskets that provide resistance tû the lûg
passing out of the collection tube. Clearly, it is preferable for the logs to bedi ,.,I~,cd from the collection tube m a smooth, c- .. ,~ i and progressive
25 marmer. However, such mPrh~nir~l devices are crude, unreliable and not
adapted for adjusting or modifying the rate of discharge during operation of
the collection .~
Clearly, what is needed is an apparatus and method that overcome
the problems and dPfiriPnrip~ inherent in the prior art. In particular, what is
30 needed is a logmaking apparatus which will produce strong, highly oriented,
flash-spun, ~ b~l~,hwilldàble fibOEs when formed into logs. Other
objects and ~ ~IL~ ,., of the present invention will become apparent to
those skilled m the art upon reference to the attached drawings and to the
detailed tlP~rriptir,n of the invention which h~ICUI~Çt~I follows.
SUBSTITUTE SHEET (RULE 26)
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~I WO 96105339 1. 2 1 9 6 7 5 9
The objects of the invention are achieved by the provision of an
apparahus for collecting cnntinnn-lC fibers moving with a shream of relatively
high speed g~es into a nozle section arranged to receive the fibers and high
speed gases to gradually slow the gases and fibers prior to collection thereof
5 in a collection hube. The nozzle section has a diverging internal contour
wherein it has a diverging half angle of less than or equal to about 20
degrees and the collection hube is arranged to discharge the gases through
the periphery and collect the fibers in a rod-shaped batt in the cenh al
passage thereof.
The objects of the invention are also achieved by the provision of
an apparahus for collecting c.",l;",..,,l~ fibers moving with a stream of
relatively high speed gases therein into a collection nube. The fibers are
formed into a rod-shaped batt in the central passage thereof and a
cnnctriefion device is connected to the outlet of the collection hube for
15 c- .. .~ .g the central passage to conhrol the rate at which the rod-shaped
bat moves therethrough.
BriPf DP~- ription of the Drawin~c
An .... ~ .g of the above and other objects of fhe invention
will now be more fully developed by a detailed description of the preferred
20 F~mhotlimt~nt The ahached drawings, in CUIljul~ iull with the following
tlF ~ ;n~, may provide a more clear ~-..~ ,.I;..g of the invention. In the
drawings:
Figure I is a InngihlAin~l cross sectional view of a logm~king
apparahus which would be typical of the prior art;
Figure 2 is a 1. .~ 1 cross sectional view similar to Figure I
except of the preferred ~ ..hotl.... .1 of the improved loer ' g apparahus
according to the present invention;
Figure 3 is an enlarged 1. ., .~; l . ,.1; . .~1 cross sectional view of the
nozle section of the apparatus of the present mvention;
~ 30 Figure 4 is a transverse cross sectional view of the improved log
making apparatus taken along Ime 3-3 in Figure 2; and
Figure 5 is a La~ lt~ y p~ ive view of the end of the
discharge section with parts removed to reveal particular features of the
invention.
Dectrirtion ofthl~Prio}Art~"n~r~fnc
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Referring to Figure I of the drawings, the apparatus generally
indicated by the number 50 is l~ ahV~ of prior art ~ ; The
apparatus 50 generally comprises a tubular collection chamber 55 including
a plurality of gas release ports 57. Fiber is delivered from a spinneret 41
5 through a broadly diverging conically shaped transition portion 42 into the
collection chamber 55. Fiber collection is initiated by a .. 1,~.".. ~1 gate 61
which swings down to block the exit of the collection chamber 55. Once the
fiber batt has formed, the gate 61 is opened to allow the batt to move out the
exit of the collection tube 55. In practice, the formation of the batt is faster10 than the rate at which the m~rh~nil~l gate 61 can be opened for satisfactory
initiation of the batt.
Movement of the batt out of the tube 55 is slowed by a series of
rubber gaskets 65 sized slightly smaller than the interior of the collection
tube 55. However, depending on the size and ~, . ,~.,11.. ,. ~ . of the log, the log
lS may move at various rates from the collection tube 55.
D~ot~ lD~crri~ti-nofthePreferredl~...ho~1;..,~..,1~
Referrmg now more ~ to Figures 2,3 and 4 of the
drawings, a preferred ~ o.li.. 1 of the apparatus for making flash-spun
c.~..li.. ~u.l ~ b~hwill.ldl~lc fiber is generally mdicated by the number 100.
20 The apparatus lû0 is attached to the exit tumnel 92 at the spinneret 91 of a
conventional flash-spinning device 90. The apparatus 100 generally
comprises three portions: (I) a nozzle section, generally indicated by the
number 120; (2) a collectiûn section, generally indicated by the number 150;
and (3) a discharge section, generally indicated by the number 180. The
25 three sections 120, 150 and 180 are cormected preferably coaxially end to
end such that the fber is spun at the spinneret 91, passes through the tuImel
92 and into the apparatus 100, through the nozle section 120, through the
collection section 150, and finally through the discharge section 180.
The nozle section 120 comprises a generally open ended tube
30 121 having open interior 122 and oriented generally coaxial with the tunnel
92. The nozle portion 120 is provided with suitable flanges 125 and 126 at
the ends thereof for al i~ - .1, . "~ to the flash-spinning device 90 and the
collection section 150, ~ u~;Li~v~,ly. The open interior 120 has a generally
circular cross section along its length through the nozle portion 120 and the
35 interiorl22islargerattheexitendl32thanitisattheinletendl31. The
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nozzle section preferably has a length of at least 1.5 times its diameter at theinlet end thereof and an internal contour that preferably diverges from the
inlet to the outlet. As will be described below, the diverging contour is not
necessarily " .. . 1 l ", l~ or always diverging, but preferably does not include
5 any portions with reducing diameter.
The open interior 122 includes a particular geometry which has
two stages 135 and 140. The first stage 135 is generally cylindrical and
extends for about 0.5 to 10 times the diameter thereof. The diameter of the
first stage 135 is preferably larger than the diameter of the tunnel 92 such
10 that the fiber leaving the tunnel 92 "sees" a step change in the diameter of
the paaaay,.,way from the spinneret 91 into the nozzle portion 120. It should
be noted that such a step change is preferably a 90~ step as illustrated in the
drawing. However, it may be acceptable to arrange a step change such that
tbe angle to the axis or centerline of the device may be c~mei~l~r~hly less
15 than 90 degrees. In other words, the step may comprise a short portion that
has a shape extending perhaps 45~ relative to axis of the apparatus 100.
The step change is preferably culla;d~ d by c~mr:3ring the cross
sectional arèas of the straight cylindrical first stage 135 to the tunnel exit. It
has been found that the cross sectional area of the first stage 135 should be at20 least I .05X, but not more than 3X, of the tunnel exit cross sectional area. It
is preferred that the step increase in cross sectional area is I .IX to I .8X the
tunnel exit cross sectional area.
It is L~,uu~ .,d that the step increase between the tunnel 92 and
the first stage 135 of the nozzle section 120 provides at least two ad~ La~
25 First, it does not hinder the expansion of the jet exiting the tlmnel.
Occr~ ;~mrlly, an under expanded jet condition occurs due to minor solution
flow rate llu~,luaLiOllâ over time. Any hindrance to this under expanded jet at
the exit of the tunnel 92 may effect pl~ / structure of the spun
fibers in a negative way, such as heavy and poorly fibrillated lines and short
30 tie points in the rl~ifil~nnl~nt~ry structure.
Secondly, it is believed that the pressure flllrhl~til~ne down stream
of the tunnel become dampened out by the step change prior to such
fln-fllrfi~mg being LlallalllilL~;d back to the tunnel 92. Pressure pulses in the
tunnel 92 tend to render irregular fiber quality. These two ad~allLa~;~,;l result
35 in making "logs" having consistent fiber quality without the undesired
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WO 96~05339 . . I ~, J / ~ 6--
defects, such as, the above described heavy and poorly fibrillated lines in the
r,lP~ jf; IqrnPntqrY structure of the spum fibers.
Moving along the nozle section 120, the straight cylindrical first
stage l 35 of the two stage noz~1e section l 20 conducts the jet of solvent
5 vapor exiting the tunnel 92 to the second stage 140 of the two stage noz~le
section 120 without disturbing the directionality and stability of the jet's
axial motion. The length of the straight cylindrical first stage 135 is
a~ u~d~ 0.5X to lOX the exit diameter of the tunnel 92, and preferably
I X to 4X the exit diameter of tunnel 92.
The second stage 140 of the two stage nozle section 120
comprises a diverging conical shape extending from the generally cylindrical
first stage 135 to the exit end 132 of the nozzle section 120. The diverging
angle c~ of the second stage 140 has been found to be suitable between one
to about 20 degrees with respect to the axis or centerline of the apparatus
15 100 (also referred to as the half angle) but is preferably in the range of 4 to
12 degrees. The exit cross sectional area of the diverging second stage 140
(at the exit end 132) is at least 0. I X the cross sectional area of the collection
section 150 down stream but not larger than the cross sectional area of the
collection section 150. The preferred cross sectional area at the exit of the
20 diverging section is 0.2X to 0.75X of the cross sectional area of the
collection section 150. Also in the preferred . .,,l~o~ . .,1 the angle ofthe
diverging secûnd stage 140 is such that, if the diverging second stage 140
were projected toward the tunnel 92, it would have ~l~ ~ 'y the same
dimension as the exit of the tunnel 92 at the exit of the tunnel. In other
25 words, the diverging second stage 140, in the preferred l ..,l.o~ is
arranged so that an extension of the conical shape would intersect the tunnel
exit with a cross sectional area that 5nh~t~nti llly cu.-c ,~,undb to the cross
sectional area of the tunnel exit.
The nozle section 120 permits the ~...,l;,."~. illll and complptit~n
30 of the flashing of the solvent while allowing for gradual ~l~ c . ll . ~ l ;- --, of the
jet. Under such an ~ngPmPnt it has been found that the turbulent forces
are not as p~ullu~l--ccd and the fiber may be formed into an acceptable log.
In the improved design of the present invention however, there also includes
an illll/lU ~ in the collection section 150.
SUBSTITUTE SHEET (RULE 26)
~ W O 96105339 2 1 9 6 7 5 9 PC~r/US95/09796
The collection section IS0, as in the prior art ,.., ,..,~,..".. ,I~ is a
generally cylindrical tube 151 having a plurality of gas release ports 152 in
the peripheral wall thereof. The ports 152 are suitably spaced and sized to
permit the solvent vapor to exit while 5llhct~nti~11y ~ ILillg the fiber from
S exiting Ll.~ u~ll. However, in the present invention, the collection
section 150 mcludes a wire mesh screen 155 lining the interior of the
cylindrical bore so as to prevent fiber from easily exiting the interior of the
tube 151. As such, the solvent vapor is permitted to exit through the ports
152 at sllhst~ntiSllly the same rate as in the prior art, but the fibers are less
10 able to pass out therethrough because of the effective reduction in the size of
the ports 152. The screen used is 10 mesh to 200 mesh, preferably 35 mesh
to 100 mesh. Details about screens of specific mesh are given in Chemical
Engineers' Handbook by R.H. Perry amd C.H. Chilton, 5th Edition, Table 21-
12. The screen lSS provides enough open area for gases to escape without
15 any ~ .t~hlF pressure drop and at the same time prevents fibers from
exiting through the openings in the screen 155 along with gases. This
eliminates the ", ~ I,~ i damage to fibers that may occur m the absence of
screen due to the fibers " ,~ ;ly exitmg the gas release ports on the
collection tube. Preferably the screen is made of a Teflon h~
20 nickel to provide a tough and low friction surface for the log moving
through the collection section 150.
From tbe collection section 150, the now formed log of fiber
passes into the discharge section 180. The discharge section 180 is
comprised of a tubular section 181 having a generally i~ - r~ ,t~
25 UI~'~JIII~,I ;., bladder 185 arramged to line the interior of the tubular section
181. The terminal edges of the tubular shaped bladder 185 are suitably
sealed to the tubular section 181 so that the annular space 188 between the
bladder 185 and the tubular section 181 may receive and hold air or other
fluid through nipple 189 to change the drmension of the bladder 185 within
30 the tubular section 181. As the annular space 188 is provided with fluid, thebladder 185 constricts the passage or essentially changes the interior
dimension of the discharge section 180. To facilitate rapid evacuation of
fluid, a network or matrix of grooves 191 are cut into the imner surface of the
tubular section 181 so that fluid may move toward the nipple 189 even while
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the bladder 185 is pressed fully against the inner surface of the tubular
section 181.
Log formation is initiated by collapsmg the bladder by an impulse
of high pressure air through nipple 189. Once tbe "log" formation is
5 initiated, the bladder is allowed to quickly return to its initial dimension by
releasing the arr pressure. The resistance to "log" motion through the
bladder is thereafter controlled by inflating the bladder to desired level
during the process thus controlling the rate at which the log exits the
collection section lSO.
The gas pressure in the collection section 150 depends in some
part on the size and number of ports 152 through which the solvent vapor
may exit therefrom. The number of the ports 152 which are open depends
on where the end of the log is in the collection section 150. If the beginning
end (the end of the log into which the fibers are being fed) is close to the
nozzle exit, the pressure (or back pressure) will be much higher than if the
end of the log is closer to the discharge section 180. Acculdill~;ly, by
controllmg the rate at which the logs are permitted to exit from the collection
section 150 essentially provides control of the back pressure in the collection
section 1 50.
The back pressure has a significant effect on fiber quality and it is
preferred to control the back pressure to desired level during the process to
maimtaim the quality of the fiber. If the back pressure is too low, the "logs"
produced are too soft to handle. If the back pressure is too high, flash spun
fibers are not well fibrillated and also the process is more prone to fail due to
fibers being blown out through the gas release ports on the collection tube.
Accul-LIl~sly~ the present invention provides a significant
iIII~JIVv~ over prior art ~ , "/ . ll~ in that the industry will now be
enabled to produce backwindable fiber having higher tenacity and strength.
Backw;lld~Lblc fiber logs can now be made using a hmnnel of the type that has
long been known to provide greater tensile shrength.
Now that the apparahus 100 of the invention has been set for~,
the process in which the apparatus is used will now be described. As noted
above, the apparams is to be sl~bstihlt~d for prior fiber receiving and log
forming ~?~ngt~nn~ntc The apparabus for spinning the fiber strand is
essentially the same as described in prior art patents. However, in conhrast to
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~IW0 96105339 2 1 9 6 7 5 9 r~
the prior log making ~",.,.~",. .,1~ the spinneret includes a tunnel at the exitthereof to enhance the acceleration of the flashing solvent vapors and
provide enhanced tensile strength for the spum fibers. The fiber strand
passes from the tulmel and into the nozle section 120 where the lateral
5 expansioncontinuesinadiverging,c.",l;"",.,l~lyexpanding,.."..,~."~
gradually slowing the expamding jet of solvent vapor.
As the fiber strand passes out of the no771e section 120 and into
the collection section 150, the solvent vapor has slowed G~ .Iy S0 that
the fiber can be collected. The collection section 150 mcludes the por~s 152
10 which permit the solvent vapor to escape from the collection section. The
fiber strand is collected into the log with sufficient force to form a stable and
suitable log. Portions of the fiber which move to the periphery of the
collection conduit are retamed therein by the mesh screen while the mesh
screen does not sllbstAntiAlly create excessive back pressure in the nozzle
15 and tunnel. The log then slowly moves out of the conduit and into the
discharge section. The bladder is arranged to control the discharge of the
log based on the physical qualities of the log and the fiber therein, and on therate at which the fiber is being delivered into the apparatus.
While the invention has been described as a c~.,..l.;"A1;.", of at
20 least three illllJlV.~ to the prior 6l,l",.;" ~ it should be clearly
Im~l~t~od that not all the described il'llJlV. ~ ,llt~ are necessary together.
While it is preferable that all are used m culljll.l. L~,ll to form the preferred
apparatus as described and illustrated in Figure 2, each may be used
;".1~ . .11 of the others to improve the operation of prior ~
The above-described invention will now be illustrated by the
following non-limitmg examples.
EYRn~rle I
A solution of 12%, by weight, of high density polyethylene
(HDPE -- melt index 0.75; stress exponent 1.45; rheology number 46;
- 30 specific density 0.957; number average molecular weight 28000 and weight
average molecular weight 135000) was prepared in Freon-l I solvent at 180~
C and 1500 psi. Solution pressure was then dropped to 930 psi to create two
phase solution prior to flash spinning. Spinneret si_e was 0.047 in. and there
was no tunnel at the sphmeret exit. The spinneret was connected to the
collection tube via a 120 degree flared opening (60 degree half angle) at the
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spinneret exit as shown in Figure 1. The collection tube ID was 1.5 in. and
was 10 in. Iong. Gas release ports were 0.125 in. diameter and were 18
degree apart around the ~,h.,.~ f.,.~ c~. Gas release port rows were 0.25 in.
apart and were staggered along the length of the fiber collection tube as
5 shown in Figure 1. There was no screen inside the collection tube. Several
rubber gaskets were used at the collection tube exit to achieve desired
resistance to the log motion for log making process. A mPrh~ni~l gate was
used at the exit to initiate the loglnaking process. The overall equipment
assembly is generally as shown in Figure I .
lo During the test, polyrner flow rate was 91 pph. Fibers
",. "". ,1 .Iy projected out through the first 2 to 3 rows of gas release ports
in the collection tube by about 0.25-0.75 in. This yielded heavy axial lines
on the surface of the logs and damaged the continuity of the fibers. Also,
fibers had heavy and poorly fibrillated regions. The web tenacity was 3.4
15 gpd.
FY~mrlP 2
The solution supplied and equipment set-up were the same as in
Example I except an a~ UI 'y sized tunnel was used at the spinneret
exit. The tunnel exit diameter was 0.423 and was 0.27 in. Iong. Tunnel
20 diverging angle with respect to the center axis was 10 degrees. The turmel
opened into the collection tube.
During the test, significant tliffirnltiPc were ~ ~.1 wbile
l " "~, initial "log" formation at the start-up~ Even when "log"
formation was .,,,Lb~ ,d, the process kept failing almost i"~ n~ly
25 either due to blow out of the formed "log" from the collection tube or blow
out of fibers from the gas release ports.
EY~mrle 3
Solution supply and equipment set-up were same as Example 2
except collection tube diameter was 2.0 in.. The process formed "logs".
30 However, fibers in the "logs" were totally entangled and back windmg of
flash spun fibers from these "logs" was not feasible.
FY~m~ple 4
The solution supply and equipment set-up were same as in
EYample 2 except that a two stage nozzle, sllbst~nti~lly as illustrated in
35 Figure 2, was added at the tunnel exit. Entrance diameter of the two stage
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~WO9~/05339 ' ~ 2-1 9 6 7 5 9
nozzle was 0.51 in. creating a step incre~e in cross section area at the tunnel
exit. The length of the straight portion of the nozzle was 0.93 in.. The
diverging section had a 4 degree diverging angle with respect to center axis.
The exit diameter of diverging section was 1.00 in
During the test, both "log" formation initiation at the start as well
c~ ntimlAtinn of the "log" making process was without any ~iiiTi. . .Ix~;
However, the process appeared to be more sensitive and unstable due to
flash spun fibers ".~ ily projecting out from first few rows of gas
release ports on the collection tube.
Due to the latter problem, the contmuity of the plPYifilAmPnt~ry
structure of flash spun fibers was damaged similar to Example I . However,
unlike Example 1, the web produced during this test was very well fibrillated
and strong (5.1 gpd). Also, there were no defects, such as heavy and poorly
fibrillated regions.
EYAn~l~ 5
The solution supply and ~ Ui~ lL set-up were same as in
Example 4 except 100 mesh st~mdard screen was used inside the collection
tube as shown in Figure 2. Witb the use of the screen, problems associated
with the fibers projecting out of the gas release ports as in Example 4 were
Plimin~tP~i However, the fber was very poorly fibrillated. In order to
improve fibers fihrillAti(m, 30 mesh size screen was tried and was found
have to have excessively large openings to retain the fibers. A screen size of
50 mesh was found to be optimum for this test. It retained fibers inside the
collection tube at the same time screen opening size was large enough for
~5 the gases to escape without excessive pressure drop. The flash spun fiberswere strong and the plPYifilA~nPntory structure was very well fibrillated
similar to Example 4. At the same time, the l,a.,hwh~dability of fibers from
the logs produced during this test was extremely good and continuity of
pl~ y structure of flash spun fibers was very good as welL
~ 30 FYAn~ple 6
The solution supply and equipment set-up were the same as in
Example S except an inflatable bladder was used instead of the rubber
gaskets and tbe ...~ AI gate at the exit of fiber collection tube. The
rubber bladder was made up of neoprene rubber. The thickness of bladder
35 wall was 0.050 in. having durometer of about 70. The inside of the metal
Il
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~os6~0s339 ~ 2 1 9 6 7 5 9 r~
cylinder supporting the inflatable bladder was provided with a network of
grooves 191 to facilitate the escape of the air through the air supply entrance
hole. Air supply pressure was 45 psig.
A very short burst of 45 psig air was supplied to the bladder at the
start to initiate log formation. The air infiated the bladder to constrict down
on and close the exit of the fiber collection tube ",~ ;ly. Within a split
second the bladder retracted back to its initial position by releasing the air
pressure. Bladder diameter was matched with the diameter of "log" exiting
the fiber collection tube in a way that no air pressure was applied to the
bladder once the "log" formation had started. However, bladder was inflated
slightly during the test whenever logs appeared to be too soft to handle.
Fibers quality and "logs" quality were extremely good as
described in Example 5. In this example, both a straight tube and a short
section of bicycle tube were tried as the bladder and both were found to
function equally very well.
E~ rle 7
The solution supply and equipment set-up were the same as in
Example 6 except the preferred two stage no_zle was replaced by single
stage diverging nozzle at the tunnel exit. This nozzle did not have straight
cylindrical section at the entrance and had only a conical diverging section.
However, there was a step increase in cross section area at the tunnel exit
due to noz_le entrance diameter 0.51 in. as compared to tunnel exit diameter
0.423 in. The diverging angle of the no7~1e was 4 degrees with respect to
center axis and exit diameter was 1.0 in. as in Example 6.
During the test, the process w~ not as stable ~ Example 6
(n. .. ~ in "log" motion velocity). Also, fibers in the "log" were not
packed in a very l)~Lwil- ial,l~ manner ~ in Example 6.
FYZ~ 8
The solution supply and equipment set-up were the same as in
30 Example 7 except that the nozzle at the tunnel exit had neither a straight
section (like Example 7) nor a step incre~e in cross sectional area at the
tunnel exit (unlike Example 7). The entrance diameter of the no771e was
0.450" as compared to tunnel exit diameter 0.423". The diverging angle was
4 degrees (half angle) and exit diameter was 1.0 in. similar to Example 7.
SUBSTITUTE SHEET (RULE 26~
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plPYifilPmPntpry structure of flash spum fibers in logs formed
during this test was very poorly fibrillated. This test was repeated with an
increased diverging angle to the sarne angle as the tunnel diverging angle,
i.e. 10 degrees. Fibrillation of p~PYif l~mPntPry structure did improve,
5 however, the process w~ still very un~pticfprt~ry~ Also, "log" formation
process became unstable.
F.Y~mr1P 9
The solution supply and equipment set-up were the same as in
Example 6 except that the collection tube had gas release ports 9 degrees
10 apart in each row instead of 18 degrees apart. The screen size was 50 mesh.
During the test, fibers blew out through the screen and the gas
rele~e ports. As such, the logs produced during this test were
Although particular .,IlBJodi~ llti, of the present invention have
15 been described in the foregomg ~ t"..., it will be ulld~ uod by those
skilled in the art that the invention is capable of numerous modifications,
5.~1,~; .llll;l.llS and rpp~rlgpnnpntc without departing from the spirit or
essential attributes of the invention. Reference should be m_de to the
appended clairns, rather tham to the foregomg ~ , ~ mdicating the
20 scope of the invention.
13
SUBSTITUTE SHEET (RULE 26
