U.S. patent number 3,608,041 [Application Number 04/885,996] was granted by the patent office on 1971-09-21 for spinning process.
This patent grant is currently assigned to Celanese Corporation. Invention is credited to Joseph Germano Santangelo.
United States Patent |
3,608,041 |
Santangelo |
September 21, 1971 |
SPINNING PROCESS
Abstract
A method of spinning fiber-forming material comprising forming
three frustoconical portions, each having an apex angle larger than
the foregoing section, and including a cylindrical portion
downstream, the frustoconical portions being divergent to the
upstream end thereof, said method permitting the production of
lower denier material at a lower drawdown with superior mechanical
properties and being characterized by ease of mechanical production
to minimize jet deposits and prolong jet life.
Inventors: |
Santangelo; Joseph Germano
(Morristown, NJ) |
Assignee: |
Celanese Corporation (New York,
NY)
|
Family
ID: |
27407145 |
Appl.
No.: |
04/885,996 |
Filed: |
December 17, 1969 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
750839 |
Aug 7, 1968 |
|
|
|
|
336683 |
Jan 3, 1968 |
3537135 |
|
|
|
Current U.S.
Class: |
264/211.17;
264/205; 264/184; 264/207 |
Current CPC
Class: |
B29C
48/05 (20190201); D01D 4/02 (20130101); B29C
48/345 (20190201); B29C 48/12 (20190201) |
Current International
Class: |
B29C
47/30 (20060101); D01D 4/00 (20060101); D01D
4/02 (20060101); B28b 003/20 (); D01f 003/26 () |
Field of
Search: |
;18/855
;264/206,176,177,200,207 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Woo; Jay H.
Parent Case Text
This application is a divisional of U.S. application Ser. No.
750,839 filed Aug. 7, 1968 now abandoned, which in turn is a
continuation-in-part of U.S. application Ser. No. 336,683 filed
Jan. 9, 1964, now U.S. Pat. No. 3,537,135.
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. In a process for spinning manmade fibers by forming a spinnable
liquid of a fiber-forming material selected from the group
consisting of cellulose esters, polyamides, polyesters, acrylic
polymers, vinyl chloride polymers and vinylidene cyanide polymers
and passing said liquid in the form of a stream through a
spinnerette orifice of a spinnerette or jet plate, the improvements
comprising (1) converging said stream in a first zone into an
initial frustoconical stream at a defined apex angle in a smooth
flow pattern, (2) passing said stream to a second zone and further
converging said initial frustoconical stream at a second apex angle
at least 30.degree. less than said defined apex angle into an
intermediate frustoconical stream, (3) subsequently passing said
stream to a third zone and further converging said intermediate
frustoconical stream at a third apex angle at least 13.degree. less
than said second angle, said third angle being about 17.degree. or
less, into a final frustoconical stream, (4) passing said stream to
a fourth zone and forming said stream in a continuing smooth flow
pattern into a cylindrical stream, (5) passing said cylindrical
stream out of said fourth zone and (6) solidifying said stream into
filamentary material.
2. The process of claim 1 wherein said fiber-forming material is a
cellulose ester in the form of a spinnable solution thereof.
3. The process of claim 2 wherein said fiber-forming material is
cellulose secondary acetate.
4. The process of claim 2 wherein said fiber-forming material is
cellulose triacetate.
5. The process of claim 1 wherein said defined apex angle is about
60.degree. to 65.degree., said second apex angle is about 25 to
35.degree. and said third apex angle is about 12 to 17.degree..
6. The process of claim 2 wherein the cellulose ester is dispersed
in a solvent comprising a major proportion of methylene chloride
and up to about 15 percent by weight of a lower alkanol.
7. The process of claim 2 wherein the filaments formed are taken up
at a linear speed of at least 300 meters per minute.
8. The process of claim 1 wherein the initial frustoconical stream
has a length of about 20 to 30 times the diameter of the
cylindrical stream; the intermediate frustoconical stream has a
length about 3 to 8 times the diameter of the cylindrical stream;
the final frustoconical stream has a length of about one half to 1
times the diameter of the cylindrical stream; said cylindrical
stream having a diameter of about 0.025 to 0.50 millimeters and a
length about one half to 10 times its diameter.
9. The process of claim 8 wherein said cylindrical stream has a
diameter of up to about 0.060 millimeters and a length about one
half to 11/2times its diameter.
10. The process of claim 9 wherein said cylindrical stream has a
circular cross sectional diameter no greater than about 0.034
millimeter and a length of about one half times its diameter, the
initial frustoconical stream has an apex angle of about 60.degree.
and a length of about 22.5 times the diameter of the cylindrical
stream, the intermediate frustoconical stream has an apex angle of
about 30.degree. and a length about 6 times the diameter of
cylindrical portion, and the final frustoconical stream has an apex
angle of about 17.degree. and a length of about one times the
diameter of said cylindrical stream.
11. The process of claim 16 wherein said defined apex angle is
about 60.degree., said second apex angle is about 30.degree. and
said third apex angle is about 17.degree..
Description
BACKGROUND OF THE INVENTION
The present invention relates to a novel spinning process.
In spinning a man-made fiber-forming material such as cellulose
triacetate into filaments, a liquid comprising the polymer, i.e., a
solution of the polymer in an appropriate solvent or a molten
composition containing the material, is extruded through fine
capillary orifices. While satisfactory products have been obtained
with orifices having profiles heretofore used, the formation of
these orifices is often difficult and costly and/or their use in
the spinning process results in various process disadvantages,
e.g., the formation of excessive amounts of deposits in the
orifices resulting in high pressure drops across the spinneret and
necessitating the use of larger than desirable orifices which have
a diverse effect on fiber properties, and difficulties in starting
up the process.
In dry spinning, since the filaments are not normally given an
after-stretch, the major orientation imparted to the fiber takes
place in the vicinity of the jet. Since fiber properties are
related to the degree of orientation, it is desirable to have a
detailed understanding of this mechanism.
The flow profile or velocity distribution of the fluid leaving the
jet is a function of the orifice design. The pressure distribution
throughout the orifice is also related to orifice design. If we
assume that the major flow pattern, e.g., smooth flow lines vs.
turbulence, is translated down to the smaller element, the
molecule, then a smooth flow pattern through the orifice will
orient the molecules along their major axis whereas turbulence
would produce random nonoriented molecules.
An analysis of orifice design, as related to velocity and pressure
distributions, shows that the flow lines are smooth and undisturbed
over the continuous portion of the orifice. It was found that when
the polymer flow meets an angle or other discontinuous surface,
eddy currents and turbulence set in. This condition becomes worse
as the velocity of the polymer through the orifice is increased.
These conditions are not conducive to molecular orientation and
disrupt molecular alignment. The correct rate of change of
curvature eliminates this disruption and improves yarn properties
and this same mechanism also contributes to a reduction in jet
corrosion.
The ideal solution to the problem of turbulence is a jet with a
smooth hyperbolic approach to the orifice. This design minimizes
flow turbulence and produces greater orientation in the yarn. To
produce pure hyperbolic holes in a spinneret would be extremely
difficult and impractical, but the novel technique developed by
applicant is an excellent inexpensive approximation. Yarn tenacity,
elongation and jet deposits are unexpectedly improved with a
decrease in turbulence caused by a decreases in the orifice
incidence angle. Therefore, the preferred jet design for both
quality and productivity, especially with regard to jet deposits,
combined a smooth hyperbolic approach and an incidence angle which
approaches zero.
It is an object of this invention to provide a process for the
formation of man-made fiber-forming materials such as cellulose
triacetate into filaments using an improved spinning process.
It is a further object of this invention to provide a spinning
process using a novel jet or spinneret whereby the problem of
turbulence in spinning filaments is eliminated, as evidence by a
reduction in jet deposits, a reduction in pressure drop across the
spinneret and the production of yarn having extremely high tensile
properties.
It is a still further object of this invention to provide novel
jets or spinnerets having a specified profile which may be produced
using a relatively simple manufacturing operation.
Other objects will be apparent from the following detailed
description and claims wherein all parts are by weight unless
otherwise indicated.
DISCUSSION OF THE PRIOR ART
The spinneret of this invention represents an improvement over the
prior art spinneret disclosed in U.S. Pat. No. 3,210,451, to
Manning, issued on Oct. 5, 1965, on an application filed on Dec. 1,
1960. This patent is assigned to the assignee of the present
application. In addition to the advantages of Manning's spinneret,
applicant's apparatus and process significantly reduce jet deposits
which cause great pressure drops across the spinneret and allow the
production of high tenacity and high elongation fibers by utilizing
a smooth approach to the capillary. Jet deposits tend to form when
there is a sharper line of demarcation between the smallest or
first frustoconical section and the bottom cylinder or
capillary.
SUMMARY OF THE INVENTION
In accordance with one aspect of the invention, a fiber-forming
material, such as cellulose triacetate or cellulose secondary
acetate, is formed into filaments by extruding a liquid comprising
such material, e.g., a solution of such material in an appropriate
solvent or a molten composition containing such material, through
an orifice having a cylindrical portion communicating with the
outlet face of the spinneret and three frustoconical portions which
are divergent toward the inlet side of the spinneret, with the apex
angle of each frustoconical portion being larger, the farther away
it is from the cylindrical portion. Thus, if the frustoconical
portion adjacent to the cylindrical portion is termed the first
frustoconical portion, then the second frustoconical portion
adjacent to the first has an apex angle larger than that of the
first and the third frustoconical portion adjacent to the second on
the inlet side has an apex angle greater than that of the
second.
The first frustoconical portion, i.e., that communicating with the
cylindrical portion preferably has an apex angle of less than about
17.degree. , e.g., 12 to 17.degree. , and most suitably in the
range of 16 to 17.degree.; the second frustoconical portion
communicating with the first frustoconical portion preferably has
an apex angle of at least 13.degree. greater than the apex angle of
the first frustoconical portion and most suitably in the range of
25 to 35.degree.; and the third frustoconical portion communicating
with the second frustoconical portion preferably has an apex angle
of at least 30.degree. greater than that of the second
frustoconical portion and most suitably in the range of 60 to
65.degree..
The use of an orifice having the above-described profile allows for
an orifice size, e.g., expressed as diameter, of the cylindrical
portion, which is smaller than usual. The use of smaller holes,
e.g., as low as 0.025 mm., allows for the production of lower
denier material, e.g., as low as 1 denier per filament, produced at
a lower drawdown or "spin draw" ratio, defined as the ratio of the
denier of the fiber-forming material being extruded to the denier
of the taken up material. This type of material is very desirable
for certain uses, e.g., cigarette filters. Moreover, smaller holes
with the concomitant employment of smaller drawdown ratios also
result in superior mechanical properties, e.g., tenacity and
elongation.
The term "cylindrical" is employed herein for the jet face section
of the orifice design since it connotes a generally regular cross
section, as distinguished from the diameters of the remaining
sections, but it is understood that such cross section may be
circular or any noncircular configuration conventional in this art
such as triangular cross sections, square cross sections, Y cross
sections, I-beam cross sections, X cross sections, trilobal cross
sections and the like.
Suitably, the length of the cylindrical portion along the axis of
the spinneret is about one-half to 10, preferably 1/2 to 1 1/2
times the diameter of the cylindrical portion, the length of the
first frustoconical portion is about 1/2 to 1 times the diameter of
the cylindrical portion; the length of the second frustoconical
portion is about 3 to 8 times the diameter of the cylindrical
portion, and the length of the third frustoconical portion is about
20 to 30 times the diameter of the cylindrical portion.
Preferable ranges of linear values for the dimensions of each
portion of the orifice are as follows: about 0.025 to 0.50 mm.,
preferably about 0.025 to 0.060 mm. for the diameter of the
cylindrical portion; about 0.0125 to 0.50 mm., preferably about
0.0125 to 0.060 mm. for the length of the cylindrical portion;
about 0.030 to 0.040 mm. for the length of the first frustoconical
portion; about 0.1 to 0.23 mm. for the length of the second
frustoconical portion; and about 0.76 to 0.89 mm. (i.e., about 30
to 40 mils) for the third frustoconical portion.
A particularly desirable spinneret of the type described above is
one having orifices each with a cylindrical portion having a
circular cross-sectional diameter no greater than about 0.034 mm.
and a length of about 1/2 times the diameter of the cross section,
a first frustoconical portion having an apex angle of about
17.degree. and a length of about 1 times the diameter of the
cylindrical portion, a second frustoconical portion having an apex
angle of about 30.degree. and a length of about 6 times the
diameter of the cylindrical portion, and a third frustoconical
portion having an apex angle of about 60.degree. and a length of
about 22.5 times the diameter of the cylindrical portion, all the
lengths being measured along the axis of the orifice.
The process is of particular value in the dry-spinning of cellulose
triacetate from solution in a solvent comprising a major amount of
a halogenated hydrocarbon.
Novel spinnerets of this invention may be made without frequent
breakdown of drilling tools by first countersinking a hole with a
tool having an angle equal to that of the third frustoconical
portion, the depth of such hole corresponding to the length desired
for such third frustoconical portion. A drilling or countersinking
tool having an angle corresponding to the second frustoconical
portion, i.e., less than that of the first tool used, is then
inserted into the hole and used to further drill a hole to an
increased depth corresponding to the desired length of the second
frustoconical portion. A cylindrical tool is inserted into the hole
and used to drill the cylindrical portion of the orifice which
extends entirely to the outlet face of the spinneret. Finally, a
punch is used to form the first frustoconical portion by pressing
down the circle of intersection between the second frustoconical
portion and the cylindrical portion, using a punching tool with an
angle corresponding to the desired first frustoconical portion.
After the first operation resulting in the formation of a
cone-shaped hole including a part corresponding to the third
frustoconical portion, the placing of each drilling tool is
simplified by the fact that it need only be inserted into an
already formed hole.
It can be seen that when using the above-described method, the
relatively weak drilling tools, i.e., the tool used to drill the
cylindrical portion and the frustoconical portions of smaller apex
angles, are only employed to drill relatively small proportions of
the total thickness of the spinneret plate. This has the effect of
drastically reducing breakage of the drilling tools.
The cylindrical portion of the orifice may be punched rather than
drilled, in which case such section may have, in addition to a
circular cross section, cross sections of other shapes, such as a
triangular cross section, a square cross section, etc., depending
upon the shape of the punching tool.
Contemplated under this invention are spinnerets having plates with
thicknesses up to about 7.62 mm., i.e., about 300 mils. However, to
avoid an unduly large amount of breakage of drilling and/or
punching tools, particularly when the spinneret is to be used in a
dry spinning process, a plate having a relatively small thickness
is suitably used, e.g., no greater than about 1.016 mm., i.e.,
about 40 mils, and most suitably in the range of about 0.635 to
1.016 mm., i.e., about 25 to 40 mils. Moreover, the use of a
spinneret plate of small thickness has the further advantages that
it results in lower pressure drop across the spinneret plate making
spinning easier and reduces the chance of blockage of the
orifice.
As mentioned previously, the process of this invention is
particularly useful in the dry spinning of cellulose esters, such
as the spinning of cellulose triacetate from solution in a solvent
comprising a major proportion of a halogenated hydrocarbon. The
process may be suitably carried out using fairly high spinning
speeds using 100 to 1,000 meters per minute to produce filaments
having a denier in the range, for example, of 1 to 10 denier per
filament. However, deniers outside of this range may also be
obtained.
As employed herein, cellulose triacetate has reference to cellulose
acetate having fewer than about 0.29 and preferably fewer than
about 0.12 free hydroxyl group per anhydroglucose unit of the
cellulose molecule, i.e., an acetyl value calculated as combined
acetic acid by weight of at least about 59 percent and preferably
at least about 61 percent.
Advantageously its intrinsic viscosity ranges from about 1.5 to 2.5
and is preferably about 2, and it is present in the dope to a
concentration ranging from about 20 to 25 percent. In place of
methylene chloride, the dope solvent may comprise other halogenated
lower alkanes such as ethylene dichloride or propylene chloride.
Advantageously, up to about 15 percent by weight of the dope
solvent comprises a lower alkanol such as methanol, ethanol,
isopropanol, etc. The preferred dope solvent is methylene
chloride-methanol in the proportions of about 90- 10 by weight.
The process of this invention is also especially useful in the dry
spinning of cellulose secondary acetate from solution in a solvent
such as acetone. Cellulose secondary acetate, as employed herein,
has reference to cellulose acetate having an acetyl value in the
range from 54 to 56 percent, preferably between 54 and 55 percent,
calculated as combined acetic acid.
For convenience, the invention has been described and illustrated
with reference to the dry spinning of cellulose triacetate, but it
should be understood that both the process and apparatus are
applicable to the spinning of other fiber-forming materials by wet,
dry or melt spinning such as polyamides, polyesters, acrylics,
vinyl chloride and vinylidene cyanide polymers and the like. Since
the essential operative principle stems from rheological rather
than chemical or mechanical characteristics, and suitable
dimensional adaptations may easily be achieved within the context
of such systems.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention may be further illustrated with reference to the
accompanying drawing wherein:
FIG. 1 is a plane view of a section of a spinneret used in
accordance with this invention with the orifices arranged in a
circle around the periphery of the spinneret plate and their size
exaggerated to indicate their appearance;
FIG. 2 is a sectional view showing the profile of the contemplated
orifices, and;
FIG. 3 is a schematic illustration of a dry spinning operation.
Referring now more particularly to the drawing, FIG. 1 shows a
spinneret or jet plate 10 as viewed from the inlet side with
orifices 11 each of which has the appearance of four concentric
circles corresponding to the largest diameter of the orifice at the
inlet face of the plate and the circles of intersection of the
various frustoconical portions and the cylindrical portion, at the
outlet side of the spinneret plate.
As shown in FIG. 2 illustrating the profile of the contemplated
orifice of spinneret 10, the wall of the cylindrical portion is
indicated at 13 with numeral 14, 15 and 16 identifying the walls of
the first, second, and third frustoconical portions of the orifices
respectively.
In Figure 3 there is shown a dry spinning cabinet 17 to which dope
is supplied through a pipe 18, being extruded through the spinneret
10 of FIGS. 1 and 2. Hot air is admitted to the cabinet 17 at 19
and is exhausted at 20 along with vapors of the dope solvent. The
filaments 21 leaving spinneret 10 pass about a guide 22 and leave
the cabinet at 23 being pulled as a yarn 24 by draw rolls 25. The
yarn 24 passes through a guide 26 and is twisted and taken up on a
bobbin 27 by a conventional collector such as ring spinner 28.
In addition to the fact that smaller orifices may be used in
carrying out the process with the advantages described above, the
process of this invention results in the formation of substantially
less jet deposits than when various other orifice shapes are used,
particularly in the case of the dry spinning of cellulose
triacetate from solution in a solvent comprising a major proportion
of a halogenated hydrocarbon. Moreover, the employment of the
orifice profile of this invention results in considerably longer
jet life, a more uniform filamentary product (e.g., in terms of
cross section) with better properties, e.g., of tenacity and
elongation that is the case when spinnerets are employed with more
conventional orifice designs. Improved dyeing properties may also
be obtained.
Finally, the process of the invention using the distinct orifice
shape as described above may be started up much more easily than
other spinning processes, and makes possible the employment of
higher spinning speeds without deterioration of filament
properties.
The following example further illustrates the invention:
EXAMPLE I
A 22 weight percent solution of fiber-forming cellulose triacetate
having an acetyl value of 61.5 percent by weight calculated as
combined acetic acid in a solvent mixture consisting of 91 percent
of methylene chloride and 9 percent of methanol was extruded
through a chromium plated stainless steel spinneret with a plate
having a thickness of 1.016 mm. and with 5 orifices arranged in a
circle each with a profile as indicated in FIG. 2. Cylindrical
portion 13 of each orifice had a circular cross section with a
diameter of 0.034 mm. and a length of 0.018 mm. First frustoconical
portion 15 had an apex angle 17.degree. and a length of 0.035 mm.;
second frustoconical portion 16 had an apex angle of 30.degree. and
a length of 0.20 mm.; and third frustoconical portion 17 had an
apex angle of 60.degree. and a length of 0.762 mm., each of the
lengths being measured along the axis of the orifice. The resulting
filaments passed through air in a spinning cabinet at 35.degree. C.
and were taken up on a bobbin at a linear speed of 500 meters per
minute after being withdrawn from the spinning cabinet. The yarn
had a denier of 3.75 d.p.f., a tenacity of 1.35 grams per denier
and an elongation of 35 percent.
After 24 hours of continuous operation from the time that the
spinneret was installed, the jet deposits resulted in a reduction
in orifice area equal to only 1.7 percent of the total due to
deposited material when observed at 400 magnification. This
represents a substantially smaller formation of jet deposits than
is obtained when orifices of more conventional profile are
used.
EXAMPLE II
A 22 weight percent solution of fiber-forming cellulose triacetate
having an acetyl value of 61.5 weight percent was extruded through
the chromium plated stainless steel spinneret of example I
utilizing the procedure of example I. The resulting filaments pass
through air in a spinning cabinet at 40.degree. C. and were taken
up on a bobbin at a linear speed of 350 meters per minute after
being withdrawn from the spinning cabinet.
A 22 weight percent solution of fiber-forming cellulose triacetate
having an acetyl value of 61.5 percent was extruded according to
the procedure of the example of U.S. Pat. No. 3,210,451, Manning,
utilizing the spinneret disclosed therein. The resulting filaments
were passed through air in a spinning cabinet at 40.degree. C. and
were taken up on a bobbin at a linear speed of 350 meters per
minute after being withdrawn from the spinning cabinet.
Table I below shows the comparative jet deposit ratings of
spinnerets utilized for long periods of time in the process of this
invention and the prior art process and jet of U.S. Pat. No.
3,210,451:
---------------------------------------------------------------------------
TABLE
I Prior Art Jet- plated Jet of this invention-plated
__________________________________________________________________________
Spinning % Spinning % Jet Time Deposits Jet Time Deposits No. hrs.
(400 X) No. hrs. (400 X)
__________________________________________________________________________
1 102 5.50 1 102 1.90 2 102 3.70 2 102 1.60 3 300 4.20 3 282 1.70 4
300 3.40 4 300 1.40 5 300 3.10 5 300 4.20 6 300 5.10 6 300 3.60 7
300 3.50 7 300 4.00 8 300 5.00 8 300 2.80 9 300 10.10 9 300 2.50 10
300 4.10 10 300 3.32
__________________________________________________________________________
As received average 4.80 As received average 11 3.10
Boiled 3 Hrs. in Methylene Chloride:
Average 2.60 Average 1.40
__________________________________________________________________________
Cellulose triacetate filaments extruded according to the foregoing
procedures was put on cones and beams and data collected for a
period of six months. Data comparing efficiency and tensile
properties of filaments extruded utilizing the Manning spinneret
with filaments utilizing the spinneret and process of this
invention are shown in table II below:
---------------------------------------------------------------------------
TABLE
II Prior Art Jet of this Plated Invention-Plated
__________________________________________________________________________
Bleb Rate/M lbs. 4.5 3.4 Part-runs, % 5.0 3.9 Tenacity, g.p.d. 1.23
1.25 Elongation, % 31 31 Major Lindly/BTY 230 150 Beam Rejection, %
3.1 2.8 Cone Rejection, % 5.5 4.5
__________________________________________________________________________
EXAMPLE III
Fiber-forming cellulose triacetate was extruded according to the
procedure of example I utilizing unplated stainless steel
spinnerets having the dimensions of the spinneret of example I. The
resulting filaments were passed through air in a spinning cabinet
at 25.degree. C. and were taken up on a bobbin at a linear speed of
500 meters per minute after being withdrawn from the spinning
cabinet. C.
Cellulose triacetate was extruded according to the procedure of the
example of U.S. Pat. No. 3,210,451, Manning, utilizing an unplated
spinneret having the dimensions of the spinneret of the said
example. The resulting filaments were passed through air in a
spinning cabinet at 25.degree. C. and were taken upon a bobbin at a
linear speed of 500 meters per minute after being withdrawn from
the spinning cabinet.
A comparison of the jet deposit data for jets run for 24 hours
utilizing the process of this invention and the prior art process
and jet of U.S. Pat. No. 3,210,451 is shown in table III below:
---------------------------------------------------------------------------
TABLE III ##SPC1##
EXAMPLE IV
A 22 weight per cent solution of fiber-forming cellulose triacetate
having an acetyl value of 61.5 percent by weight calculated as
combined acetic acid in a solvent mixture consisting of 91 percent
of methylene chloride and 9 percent of methanol was extruded
through an unplated stainless steel spinneret at a jet face
temperature of 80.degree. C. The spinneret having a plate with a
thickness of 1.016 mm. and with 20 orifices arranged in a circle
each with a profile as indicated in FIG. 2. Cylindrical portion 13
of each orifice had a circular cross section with a diameter of
0.028 mm. and a length of 0.018 mm. First frustoconical portion 15
had an apex angle 17.degree. and a length of 0.035 mm.; second
frustoconical portion 16 had an apex angle of 30.degree. and a
length of 0.20 mm.; and third frustoconical portion 17 had an apex
angle of 60.degree. and a length of 0.762 mm., each of the lengths
being measured along the axis of the orifice. The resulting
filaments passed through a 12-foot updraft in a spinning cabinet at
35.degree. C. and were taken up on a bobbin at a linear speed of
300 meters per minute after being withdrawn from the spinning
cabinet. The yarn was wound onto one pound packages and had an
average tenacity of 1.33 grams per denier and an average elongation
of 49.0 per cent.
---------------------------------------------------------------------------
TABLE IV
Bobbin No. Denier Ten., g./d. Elong., %
__________________________________________________________________________
1 74.6 1.32 51.5 2 72.8 1.33 49.2 3 76.8 1.36 48.9 4 74.3 1.35 48.0
73.1 1.33 47.8 6 75.5 1.35 49.0 7 75.0 1.33 49.2 8 75.2 1.32 47.1 9
76.0 1.30 49.7 10 75.0 1.32 46.8 11 75.7 1.35 49.0 12 72.9 1.35
47.1 13 75.5 1.32 51.1 14 74.7 1.34 51.1 15 74.7 1.35 49.9
__________________________________________________________________________
Average 74.8 1.33 49.0
__________________________________________________________________________
Spinning speeds in excess of 1,000 meters per minute are easily
achieved utilizing the process and spinneret of this invention. In
addition, the life of the spinneret in use ranges from about 1,000
to 1,500 hours, as compared with a useful life of 600 hours for the
prior art Manning spinneret.
* * * * *