CA2196759A1 - Apparatus and method for making logs from highly oriented flash-spun continuous fibers - Google Patents
Apparatus and method for making logs from highly oriented flash-spun continuous fibersInfo
- Publication number
- CA2196759A1 CA2196759A1 CA002196759A CA2196759A CA2196759A1 CA 2196759 A1 CA2196759 A1 CA 2196759A1 CA 002196759 A CA002196759 A CA 002196759A CA 2196759 A CA2196759 A CA 2196759A CA 2196759 A1 CA2196759 A1 CA 2196759A1
- Authority
- CA
- Canada
- Prior art keywords
- fibers
- gases
- section
- nozzle section
- flash
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
- D01D5/00—Formation of filaments, threads, or the like
- D01D5/11—Flash-spinning
Abstract
This invention relates to making backwindable rod shaped batts or logs from highly oriented flash-spun continuous fibers. The fibers are conducted from the exit of a spinneret (91) through a tunnel (92) and into a two stage diverging nozzle (120) to slow down the fibers for an organized collection in the collection section (150). The invention further includes an inflatable bladder (185) in a discharge section (181) for initiating the formation of the log and a mesh screen (155) in the collection section (150) for reducing the occurrence of fiber blow out through the gas discharge ports (152).
Description
~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
SU~SHEr (RULE 263 wo s6/0s33s 2 1 9 6 7 5 ~ P~
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) -~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 SUBSTITUTE SHEET (RULE 26) -W096/05339 -2t ~ 615~ r~l,u~
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 SU~STITUTE SHEET (RULE 26 ~; 21 96759 ~ wo s6/os33s " r~
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 SUBSTITUTE SHEET (RULE 26) : =
~t 96759 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 SUBSTITUTE SHEET (RULE 26) wo s6ros33s : 2 1 9 6 7 5 q r~
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 SUBSTITUTE SHEET !rRUI.~ 26) ~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 SUBSTITUTE SHEET lRULE 26 - . 21q675~
WO96/0s339 . . ' r~ .. ,"-1 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 SUBSTITUTE SHEET (RULE 26 ~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 SUBSTITUTE SHEET (RULE 26) ~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~
~WO 96/05339 p~
, 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.
SUBSTITUTE SHEET (RULE 26
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
SU~SHEr (RULE 263 wo s6/0s33s 2 1 9 6 7 5 ~ P~
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) -~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 SUBSTITUTE SHEET (RULE 26) -W096/05339 -2t ~ 615~ r~l,u~
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 SU~STITUTE SHEET (RULE 26 ~; 21 96759 ~ wo s6/os33s " r~
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 SUBSTITUTE SHEET (RULE 26) : =
~t 96759 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 SUBSTITUTE SHEET (RULE 26) wo s6ros33s : 2 1 9 6 7 5 q r~
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 SUBSTITUTE SHEET !rRUI.~ 26) ~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 SUBSTITUTE SHEET lRULE 26 - . 21q675~
WO96/0s339 . . ' r~ .. ,"-1 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 SUBSTITUTE SHEET (RULE 26 ~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 SUBSTITUTE SHEET (RULE 26) ~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~
~WO 96/05339 p~
, 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.
SUBSTITUTE SHEET (RULE 26
Claims (14)
1. An apparatus for forming a rod-shaped batt of continuous backwindable fibers wherein the continuous fibers are provided within a relatively concentrated stream of high speed gases such as from a fiber spinning source (90), the apparatus comprising:
a nozzle section (120) arranged to receive fibers and high speed gases and to allow the gases and fibers to gradually slow down, wherein said nozzle comprises a tube having a diverging internal contour, a length of at least 1.5 times its diameter at its inlet, and a diverging half angle of less than or equal to about 20 degrees;
a collection tube (151) arranged to receive the fibers and gases from said nozzle section and having means in the periphery thereof for discharging the gases therefrom and a central passage for collecting the continuous fibers into the rod-shaped batt.
a nozzle section (120) arranged to receive fibers and high speed gases and to allow the gases and fibers to gradually slow down, wherein said nozzle comprises a tube having a diverging internal contour, a length of at least 1.5 times its diameter at its inlet, and a diverging half angle of less than or equal to about 20 degrees;
a collection tube (151) arranged to receive the fibers and gases from said nozzle section and having means in the periphery thereof for discharging the gases therefrom and a central passage for collecting the continuous fibers into the rod-shaped batt.
2. The apparatus according to Claim 1 wherein said internal contour of said nozzle is a two stage contour and said first stage (135) is a generally straight cylinder.
3. The apparatus according to Claim 2 wherein said second stage (140) comprises a diverging conical section having an diverging angle of between 1 and 20 degrees with respect to the axis of said nozzle section.
4. The apparatus according to Claim 3 wherein the first stage (135) comprises at least five percent of the length of said nozzle section and less than fifty percent, and said second stage (140) comprises the remaining length of said nozzle section.
5. The apparatus according to Claim 3 wherein said internal contour of said nozzle section (120) has a circular cross section along the length of said nozzle section.
6. The apparatus according to Claim 1 wherein there is a step change in cross sectional area between said exit end of said nozzle section (120) and said collection tube (151).
7. The apparatus according to Claim 1 wherein said means for discharging flash-spun gases comprises a plurality of openings (152) in the peripheral wall thereof and wherein the collection tube further includes a screen (155) having a mesh size between 10 and 200 positioned within the collection tube to prevent fibers from exiting said openings (152) with the flash-spun gases.
8. The apparatus according to Claim 1 further including constriction means for blocking said passage to prevent the continuous fibers from passing along said passage thereby initiating batt formation at a start up of continuous fiber production.
9. The apparatus according to Claim 8 wherein said constriction means comprises a circumferentially arranged bladder (185) having a generally sealed annular space (188) behind said bladder and means for providing fluid into said annular space to move said bladder radially inward into said passage to effectively constrict said passage.
10. The apparatus according to Claim 8 wherein said constriction means is arranged to change the interior dimension of the passage thereby controlling the rate at which the batt may proceed along said passage.
11. The apparatus according to Claim 1 wherein the fiber spinning source that provides continuous fibers within a relatively concentrated stream is a flash-spinning device (90) and the continuous fibers provided are flash-spun fibers.
12. The apparatus according to claim 11 wherein said flash-spinning device includes a spinneret (91) through which the continuous fibers are flash-spun, and a diverging tunnel (92) having an entrance and an exit, said spinneret arranged to provide continuous fibers into the tunnel entrance, and said nozzle section has an entrance connected to the tunnel exit, the cross-sectional area of the nozzle entrance being 1.05 to 3.0 times the cross-sectional area of the tunnel exit.
13. A method for producing rod-shaped batts of continuous backwindable fibers, comprising the steps of:
providing continuous fibers within a relatively concentrated stream of high speed gases into a nozzle section (120);
gradually slowing down the gases and the fiber in an internal tube (122) of a nozzle section in which the cross sectional area of nozzle section internal tube diverges at a half angle of less than or equal to about 20 degrees; and collecting the fibers into a batt in a collection tube (151) while discharging the gases through peripheral openings (152) in the peripheral wall of the collection tube.
providing continuous fibers within a relatively concentrated stream of high speed gases into a nozzle section (120);
gradually slowing down the gases and the fiber in an internal tube (122) of a nozzle section in which the cross sectional area of nozzle section internal tube diverges at a half angle of less than or equal to about 20 degrees; and collecting the fibers into a batt in a collection tube (151) while discharging the gases through peripheral openings (152) in the peripheral wall of the collection tube.
14. The method according to claim 13 wherein the step of providing continuous fibers in a relatively concentrated stream includes flash-spinning continuous fibers through a spinneret (91) and into a tunnel (92) from which the fibers and flashed gases are directed into the nozzle section (120).
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/287,602 US5547624A (en) | 1994-08-09 | 1994-08-09 | Process of making and collecting continuous fibers in the form of a rod-shaped batt |
| US08/287,606 US5529734A (en) | 1994-08-09 | 1994-08-09 | Process for making and collecting continuous fibers in the form of a rod-shaped batt |
| US08/287,602 | 1994-08-09 | ||
| US08/287,606 | 1994-08-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2196759A1 true CA2196759A1 (en) | 1996-02-22 |
Family
ID=26964559
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002196759A Abandoned CA2196759A1 (en) | 1994-08-09 | 1995-08-01 | Apparatus and method for making logs from highly oriented flash-spun continuous fibers |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0775220B1 (en) |
| JP (1) | JPH10503813A (en) |
| KR (1) | KR100343091B1 (en) |
| CA (1) | CA2196759A1 (en) |
| DE (1) | DE69506264T2 (en) |
| ES (1) | ES2126309T3 (en) |
| WO (1) | WO1996005339A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6389646B1 (en) | 2001-07-09 | 2002-05-21 | Victoria I. Pettigrew | Fiber tumbler and method of use |
| CN116876086B (en) * | 2023-09-06 | 2023-11-28 | 江苏青昀新材料有限公司 | Flash spinning pipeline system |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3081519A (en) * | 1962-01-31 | 1963-03-19 | Fibrillated strand | |
| US3600483A (en) * | 1964-09-30 | 1971-08-17 | Du Pont | Process of flash spinning and collecting plexifilament to form rod-shaped back-windable batt |
| US4267002A (en) * | 1979-03-05 | 1981-05-12 | Eastman Kodak Company | Melt blowing process |
| US4352650A (en) * | 1981-03-24 | 1982-10-05 | E. I. Du Pont De Nemours And Company | Nozzle for flash-extrusion apparatus |
-
1995
- 1995-08-01 CA CA002196759A patent/CA2196759A1/en not_active Abandoned
- 1995-08-01 DE DE69506264T patent/DE69506264T2/en not_active Expired - Fee Related
- 1995-08-01 ES ES95929363T patent/ES2126309T3/en not_active Expired - Lifetime
- 1995-08-01 KR KR1019970700831A patent/KR100343091B1/en not_active IP Right Cessation
- 1995-08-01 WO PCT/US1995/009796 patent/WO1996005339A1/en active IP Right Grant
- 1995-08-01 JP JP8507401A patent/JPH10503813A/en not_active Ceased
- 1995-08-01 EP EP95929363A patent/EP0775220B1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| KR970704920A (en) | 1997-09-06 |
| WO1996005339A1 (en) | 1996-02-22 |
| EP0775220A1 (en) | 1997-05-28 |
| KR100343091B1 (en) | 2002-09-18 |
| ES2126309T3 (en) | 1999-03-16 |
| JPH10503813A (en) | 1998-04-07 |
| DE69506264T2 (en) | 1999-05-06 |
| EP0775220B1 (en) | 1998-11-25 |
| DE69506264D1 (en) | 1999-01-07 |
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