METHODE D'AUTO-CREPAGE D'UN FILE

SELF-CRIMPING YARN PROCESS

Abrégé anglais

ABSTRACT OF THE DISCLOSURE
In melt spinning, a first elemental stream with
extensional flow is merged with a second elemental stream
with shear flow, and the resulting combined stream is
quenched into a filament. The filament is either immediately
drawn or spun at a sufficiently high spinning speed, yielding
an oriented textured filament. The process avoids oscillations
of the molten elemental streams encountered in the prior art
processes and leads to production of a filament of substan-
tially uniform denier.

Revendications

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. A process for melt-spinning a textured filament from
a melt-spinnable polymer characterized by:
(a) generating a molten first elemental stream
portion with said polymer;
(b) generating a molten second elemental stream
portion with said polymer, said first and said second elemental
stream portions having substantially different components of
extensional flow;
(c) converging said first and said second elemental
stream portions at substantially equal velocities to merge into
a combined stream; and
(d) quenching said combined stream into a filament.
2. The process of claim 1 further characterized by
withdrawing said filament from said combined stream at a
spinning speed selected such that said filament has an elonga-
tion less than 90%.
3. The process of claim 2, characterized in that said
spinning speed is selected such that said filament has an
elongation less than 45%.
4. The process of claim 1, further characterized by
drawing said filament within three seconds after said combined
stream solidifies into said filament.
5. The process of claim 1, characterized in that said
first and said second elemental stream portions have substan-
tially equal mass flow rates.

Description

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The invention relates to the art of producing
textured filaments, and more particularly relates to the art
of producing textured filaments during the melt-spinning
process.
Privott U.S. Patent 3,3~7,327 discloses producing
self~crimping filaments ~y converging two elemental polymer
streams to merge near the face of the spinneret, the elemental
streams at the point of merging having substantially different
velocities. The combined stream is quenched into a filament
which spontaneously develops crimp upon being drawn. It has
now been discovered that inducing self-crimp by such a
technique can, under certain spinning conditions, lead to
oscillations of the molten elemental streams near the point
of confluence of the elemental streams, resulting in pro-
ducing filaments with highly variable denier.
According to the present invention, there is
provided a process for melt-spinning a textured filament which
avoids such o~cillations and which leads to production of a
filament of substantially uniform ~enier.
According to a primary aspect of the invention,
there is provided a process for me:Lt-spinning a textured
filament from a melt-spinnable polymer comprising generating
a molten first elemental stream portion with the polymer;
generating a molten second elemental stream portion wi~h the
` 25 polymer, the Eirst and the second elemental stream portions
having substantially different components of extensional flow;
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converging the first and the second elemental stream portions
at substantially equal velocities to merge into a combined
stream; and quenching the combined stream into a filament.
According to another aspect of the invention, there
is provid~d a process of the above character further com-
prising withdrawing the filament from the unitary stream at
a spi~ning speed selected such that the filament has an
elongation less than 90%.
According to another aspect of the invention, there
is provided a process o the above character wherein the
spinning speed is selected such that the filament has an
elongation less t~an 45%.
According to another aspect of the invention, there
is provided a process of the above character further com-
prising drawing the filament within three seconds after theunitary s~ream solidifies into the filament.
According to another aspect of the invention, there
is provided a process of the above character wherein the
first and the second eIemental stream portions have substan-
tially equal mass flow rates,
Other aspects of the invention will in part appearhereinafter and will in part be obvious from the following
description taken in connection with the accompanying draw-
ing, wherein the single FIGURE is a vertical sectional view
of the preferred embodiment of the combined spinneret orifice
- according to the invention.
The drawing illustrates spinneret plate 20 having
provided therethrough conical passage 22 for providing con~
- verging flow (extensional flow). A second passage extends
through plate 2G for providing non-extensional flow, com-
prising right circularly cylindrical counterbore 24 and
right circularly cylindrical orifice 26.
Passage 22 and orifice 26 thus converge first and
second elemental streams to merge into a combined stream just
below the lower face o plate 20. ~he dimensions of passage
22 and orifice 26 are selected such that the two elemental
streams have substantially equal velocities upon convergence,
and preferably such that the two elemental streams have sub-
stantially equal mass flow rates. The two elemental streams
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C-14-54-0307
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will differ substantially in their rheological states because
of their difEerent histories in flowing through their respec-
tive passages prior to convergence into the combined stream.
This difference in rheological states causes the resul~ing
yarn quenched from the combined stream to spontaneously
crimp if the yarn is oriented before ~he rheological differ-
enc~s decay. This may be done by a discrete or separate
drawing step within about 3 seconds af~er solidification of
the combined stream into a filament, or may be done without
a separate drawing step if ~he spinning speed is selected
such that the resul~ing filament has an elongation less than
90% ~preerably less than 45~/O)~ It is noted that the
elemental polymer stream through passage 22 has predominately
extensional flow, while that through orific~ 26 has predom~
inately shear flow with little or no extensional flow.
The preferred included angle of the conical surface
defining passage 22 is 30, and the axes of counterbore 24
and orifice 26 are parallel to the nearest side of passage
22. Tha~ is, the axes of counterbore 24 and orifice 26 are
preferably inclined 15 with respect to a line normal to the
opposed flat upper and lower surfaces of plate 20.
Further presently preferred dimensions include a
diameter of 0.013 inch (0.033 centimeter) for orifice 26 a~d
for the lower or outlet end o passage 22. The distance
between centers of the lower or outlet ends of passage 22
and orifice 26 is preferably 0.043 inch (0.109 centimeter).
The dimensions of counterbore 24 are selected such that the
two elemental streams exi~ing from passage 22 and orifice 26
have substantially equal velocities and preferably substan-
~ially equal mass flow rates. In the preferred embodiment,orifice 26 is 0.015 inch (Q.0356 centimeter) long, while
counterbore 24 has a diameter of 0.044 inch (0.112 centimeter).
Example I
~ylon 66 polymer of normal molecular weight for
apparel yarns is extruded at the rate of 2.83 grams per
minute through the above described combined ori~ice comprising
passage 22 and orifice 26. The resulting combined stream is
conventionally qu~nched with transverse air at a spinning
speed vf 773 ~ards (706 meters) per minute, and immediately

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drawn by a draw ratio of 2.0 to give a drawn filament with a
denier of 18. Upon hot relaxation of the filament, substan-
tial crimp is formed.
Exampl~e II
Example 1 is repeated, except that the spinning
speed is increased to 5500 yards ~5000 meters) per minute.
Upon hot relaxation o the filament, substantial crimp is
developed. The filament has an elongation of 37%.
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Rxample II is repeated, except that the polymer is
polyethylene terephthalate, the throughput is 6.96 grams
per minute, and the spinning speed is 6000 yards (5400
meters) per minute. The filament has an elonga~ion o 42%,
and develops substantial bulk upon hot relaxation.