U.S. patent number 3,900,678 [Application Number 05/064,020] was granted by the patent office on 1975-08-19 for composite filaments and process for the production thereof.
This patent grant is currently assigned to Asahi Kasei Kogyo Kabushiki Kaisha. Invention is credited to Itsuho Aishima, Hiroshi Chayamiti, Yuzuru Doi, Noboru Fukuma, Hiroshi Henmi, Toshio Okamoto, Hisaya Sakura.
United States Patent |
3,900,678 |
Aishima , et al. |
August 19, 1975 |
**Please see images for:
( Certificate of Correction ) ** |
Composite filaments and process for the production thereof
Abstract
Composite filaments comprised of two components disposed in
side-by-side or eccentric sheath-core relationship. A first
component is a crystalline polypropylene homopolymer. The second
component is a random or block copolymer of propylene and another
olefin. The composite filaments have a crimp-developing force of
more than 15%.
Inventors: |
Aishima; Itsuho (Nobeoka,
JA), Fukuma; Noboru (Nobeoka, JA), Sakura;
Hisaya (Nobeoka, JA), Chayamiti; Hiroshi
(Nobeoka, JA), Okamoto; Toshio (Nobeoka,
JA), Doi; Yuzuru (Nobeoka, JA), Henmi;
Hiroshi (Nobeoka, JA) |
Assignee: |
Asahi Kasei Kogyo Kabushiki
Kaisha (Osaka, JA)
|
Family
ID: |
27455536 |
Appl.
No.: |
05/064,020 |
Filed: |
July 20, 1970 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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588332 |
Oct 21, 1966 |
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Foreign Application Priority Data
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Oct 23, 1965 [JA] |
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40-64794 |
Feb 25, 1966 [JA] |
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41-11104 |
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Current U.S.
Class: |
428/374;
264/172.14; 264/172.15; 264/172.18; 264/DIG.26 |
Current CPC
Class: |
D01F
8/06 (20130101); Y10T 428/2931 (20150115); Y10S
264/26 (20130101) |
Current International
Class: |
D01F
8/06 (20060101); D02g 003/02 () |
Field of
Search: |
;161/173,175,177
;264/DIG.26,171 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Fritsch; Daniel J.
Attorney, Agent or Firm: Waters, Schwartz & Nissen
Parent Case Text
This application is a continuation of application Ser. No. 588,332,
filed Oct. 21, 1966, now abandoned.
Claims
What is claimed is:
1. A composite filament comprised of two components disposed in
side-by-side relationship or eccentric sheath-core relationship, a
first component being crystalline polypropylene homopolymer and a
second component being selected from the group consisting of a
random copolymer of propylene and 0.5 to 20 mole % of another
olefin and a block copolymer of propylene and 1.0 to 40 mole % of
another olefin, said other olefin of the copolymer being selected
from the group consisting of ethylene, butene-1, hexene-1,
octene-1, 4-methylpentene-1, 3-methylbutene-1 and styrene, said
composite filament having a crimp-developing force of more than 15
%.
2. The composite filament of claim 1 in which the second component
is a random copolymer containing about 3 to 10 mole % ethylene.
3. The composite filament of claim 1 wherein the crimp-developing
force of the filament is 30 to 40 %.
Description
This invention relates to composite filaments and a process for the
production thereof. More particularly, the invention is concerned
with composite filaments comprising crystalline polypropylene and
random or block copolymers of crystalline propylene.
It is well known that crimpable filaments can be formed by the
conjugate-spinning of two or more polymers in combination. However,
reports of studies on composite filaments of polypropylene are
relatively few in number. That is, as the known literature
disclosing methods for the preparation of composite filaments of
polypropylene, there are for example, only Japanese Pat.
Publication No. 9,533/65, British Pat. No. 979,083 and Belgian Pat.
No. 657,850. Substantially all of the composite filaments obtained
according to the above methods are crimpable filaments of the type
which immediately develop crimps by relaxing after drawing (this
type will be referred to as sensitive type hereinafter). However,
the composite filaments of the inventions mentioned above do not
develop substantially effective crimps by mere relaxing after
drawing. On the other hand, there are crimpable filaments of the
type which develop no crimps unless they are subjected to heat
treatment under nontensioned state after drawing (this type will be
referred to as latent type hereinafter). Few crimpable filaments of
the latent type are known.
"Kasen Geppo" (Monthly Report of Chemical Fibers), Vol. 202, May
1965 discloses at page 3 that generally, latent type composite
filaments have a low stress in developing crimps and, under a
tensioned state, they develop crimps with difficulty even when
subjected to a crimp-developing treatment, such as heat or the
like. According to the tests of the present inventors, it has been
found that every composite polypropylene filament obtained in
accordance with the above-cited methods is substantially deprived
of crimps by heat treatment under a slight stress and is a
composite filament which is inferior in this respect.
Further, the sensitive type composite filaments according to the
above methods have such a tendency that the crimps are straightened
by application of a relatively small force, and this property is a
disadvantage in certain of their uses.
On the other hand, the journal "Zairyo" (Materials), Vol. 14, No.
136 describes at page 29 that filaments obtained by subjecting
polypropylene and polyethylene to conjugate spinning suffer from
such a drawback that the two components readily separate from each
other and hence are not desirable as composite filaments.
An object of the present invention is to provide crimpable
polypropylene composite filaments having superior crimpability and
a favorable hand in which the two components employed are excellent
in mutual adhesion, and a process for producing the same.
Another object of the invention is to provide latent type
polypropylene composite filaments and a process for preparing the
same.
A further object of the invention is to provide polypropylene
composite filaments of high crimp developing force and a process
for the production thereof.
In accordance with the present invention, the first composite
filament is formed by subjecting to conjugate spinning a random
copolymer of propylene and 0.5 to 20 mole % of another olefin, and
crystalline polypropylene, while the second composite filament is
formed by subjecting to conjugate spinning a block copolymer of
propylene and 1.0 to 40 mole % of another olefin and crystalline
polypropylene.
The spinning material for the latent type composite filament of the
first composite filament comprises as one component a crystalline
copolymer of propylene and 0.5 to 20 mole % of another olefin and
as the other component crystalline polypropylene. The above
composite filament is prepared by subjecting the two components to
melt-spinning to form a side-by-side type or eccentric sheath-core
type filament and then drawing the filament to such an extent that
substantially no crimps are developed when the filament has been
relaxed after drawing. The thus obtained drawn filament is
subjected, either as such or after knitting or weaving, to a
shrinking heat treatment in a non-tensioned state to develop
crimps.
The spinning material for the latent type crimpable composite
filament of the second composite filament comprises as one
component a crystalline block copolymer of propylene and 1.0 to 40
mole % of other olefin and as the other component crystalline
polypropylene having an MFI similar to, and differing by not more
than 5.0 from that of said block copolymer. The above composite
filament is prepared by forming the two components into a
side-by-side type or eccentric sheath-core type composite filament
and drawing the filament, followed by relaxing. The thus obtained
drawn filament is subjected, either as such or after knitting or
weaving, to heat treatment in a non-tensioned state to develop
crimps.
A characteristic of the present invention is that crystalline
polypropylene is used as one component and such a crystalline
propylene random polymer or block copolymer as described is used as
the other component.
In the present invention, the polypropylene and copolymers employed
as the starting materials are those having intrinsic viscosities of
from 0.6 to 3.0, preferably from 1.0 to 2.5.
The intrinsic viscosity [.eta.] referred to herein is defined by
the following equation:
[.eta.] = lim.sub.C.sub..fwdarw.O .eta.sp/c
.eta.sp = (t/t.sub.o) - 1
wherein t.sub.o and t are, respectively, times (seconds) required
for tetralin and a tetralin solution of the polymer or copolymer to
drop at 135.degree.C. using an improved Ostwald's viscometer; and C
is the concentration (g/100 cc.) of the solution.
The term MFI employed in the present invention is defined as
follows:
A polypropylene polymer or a propylene copolymer is extruded at
230.degree.C. under a load of 2160 g through a spinneret having one
orifice of 2.1 mm and the amount extruded in 10 minutes is defined
as MFI (ASTM . D-1238).
The crystalline polypropylene employed as one component of the
starting material in the present invention is obtained by
polymerizing propylene in the presence of a stereospecific
polymerization catalyst. In the above case, polypropylene having
the desired intrinsic viscosity for the spinning material can be
obtained in one stage by adding, at the time of polymerization, a
molecular weight modifier such as hydrogen or by suitably selecting
the polymerization conditions. Alternatively, the polymer having
the desired intrinsic viscosity can be obtained by thermally
depolymerizing at the finishing step a high intrinsic viscosity
polymer once obtained at the polymerization step, or by thermally
depolymerizing said polymer in the presence of a small amount of an
organo-tin compound. The extent of depolymerization of the one
component crystalline polypropylene during the period of from
immediately after polymerization to a time when it is formed into a
spinning material, more accurately into a composite filament, is
one of the factors dominating the properties of the resulting
composite filament.
The copolymer, which is the other component of the starting
material employed in the present invention, is obtained by
copolymerizing, in the presence of a catalyst, propylene with
another olefin such as ethylene, butene-1, pentene-1, hexene-1,
heptene-1, octene-1, 4-methylpentene-1, 3-methylbutene-1 or
styrene. As the copolymerization catalyst there is used a known
stereospecific polymerization catalyst capable of polymerizing
propylene to crystalline polypropylene. Typical of such catalyst
is, for example, one comprising an organic compound of a metal of
Groups I to III of the Periodic Table and a halide of a transition
element of Groups IV to VIII of the same Table.
The preparation of the random copolymer is effected according to a
process for the polymerization of propylene. In this case, the
adoption of a continuous polymerization process is desirable in
order to control the copolymerization ratio of the resulting random
copolymer. The proportion of the other olefin to be
random-copolymerized with propylene is from 0.5 to 20 mole % based
on the copolymer. In case the proportion is less than 0.5 mole %,
the desired effect of the present invention is difficulty
attainable. Further, in case the proportion is more than 20 mole %,
the resulting copolymer is excessively lowered in melting point and
the adhesion of the two components is deteriorated, with the result
that a composite filament obtained by use of such copolymer is
greatly lowered in utility. The content of the other olefin in the
random copolymer is preferably from 3 to 10 mole %. The extent of
depolymerization of the random copolymer during the period of from
immediately after copolymerization to a time when it is formed into
a spinning material, more accurately into a composite filament, is
also one of the factors dominating the properties of the resulting
composite filament, like the content of the other olefin in the
copolymer.
The preparation of the block copolymer is carried out according to
a known process, such as for example, the process disclosed by E.
G. Kontos in "Journal of Polymer Science", Vol. 61, page 62 (1962)
or the process revealed by G. Pier in "Macromolecular Chemie", Vol.
44, page 347 (1961). That is, one block-copolymerization process is
effected by periodically and alternately contacting with a
polymerization catalyst a mixture of propylene and one other olefin
or a mixture of two or more olefins including or not including
propylene. Another copolymerization process is carried out by
periodically and alternately contacting with a polymerization
catalyst an olefin mixture composed mainly of propylene and one
other olefin, or a mixture of two or more olefins including or not
including propylene. The resulting copolymer is a non-statistic
copolymer having in alternating order in the molecular chain a
monomer composed mainly of propylene and a different monomer
composed mainly of other olefin.
The proportion of other olefin to be block-copolymerized with
propylene is preferably in the range of from 1.0 to 40 mole %.
Where the proportion is less than 1.0 mole %, the resulting
composite filament shows no sufficient development of crimps as a
composite filament. Further, where the proportion is more than 40
mole %, the resulting composite filament is deteriorated in
adhesion to one component crystalline polypropylene and is greatly
lowered in utility as a composite filament.
In order to periodically and alternately contact said olefins with
a stereospecific polymerization catalyst, subsequent olefin
monomers should be introduced either after applying the operation
of deterging the catalyst surface with an inert gas such as
nitrogen or helium to exclude preceding olefin monomers or after
reducing the pressure of the reaction system to remove preceding
olefins from the catalyst surface. It is also possible to attain
the desired effect by the application of said two operations in
combination. More simply, the block-copolymerization can be
effected by merely feeding olefins periodically and alternately to
the catalyst surface without conducting the above removing
operations. Olefin monomers may be alternated not only one time but
also any desired times. The polymerization process may be effected
in any of continuous or batch-wise manner, but a continuous
polymerization process is desirable in order to control the
copolymerization ratio of the resulting copolymer.
In order to obtain the random or block copolymer having a desired
intrinsic viscosity, a desired amount of a molecular weight
modifier such as hydrogen is fed to the polymerization system,
whereby the molecular weight of the copolymer can be controlled.
Alternatively, the molecular weight can be controlled by elevating
the reaction temperature to frequently cause a chain transfer
reaction. Another procedure to control the molecular weight is that
the molecular weight control is not effected in the polymerization
step but the resulting high intrinsic viscosity copolymer is
thermally depolymerized, before entering the spinning step, in the
presence of a slight amount of an organo-tin compound.
Either one or both of the polymer and the random or block
copolymer, which are the two components constituting the composite
filament of the present invention may contain, if necessary, up to
10% by weight of additives. Such additives are various heat
stabilizers, light stabilizers, gas-fading stabilizers, titanium
dioxide and other pigments, brightening agents and dyeing
additives. The dyeing additives include compounds of metals such as
Ni, Al and Zn; nitrogen-containing compounds such as
polyaminotriazole, polyamides, polyalkyleneimide and low molecular
weight amines; polyesters; polycarbonates and other various
compounds known to the art. Ordinarily, these additives are added
in an amount of less than 10% by weight of the polymer or
copolymer, whereby the object of addition is achieved and the
composite filament of the present invention is obtained.
For the production of the composite filaments of the present
invention, any spinning and drawing apparatuses known to the art
are usable.
In spinning a composite filament of polypropylene according to the
conventional method, there frequently occurs, due to the difference
in viscoelastic behavior of melts of the two components, such as
phenomenon that molten filaments extruded from a spinneret bend
immediately below the orifices. Accordingly, there are many cases
where uniform filaments are difficulty spun in a stable state. In
accordance with the present invention, however, the above drawbacks
encountered in the spinning according to the conventional method
are entirely overcome by suitable selection of the depolymerization
degree, intrinsic viscosity and percentage of n-heptane extraction
residue of crystalline polypropylene; the olefin component, mole %
of olefin content, depolymerization degree, intrinsic viscosity and
percentage of n-heptane extraction residue of the copolymer to be
combined with the crystalline polypropylene; and spinning
conditions, whereby an excellent latent type composite filament is
obtained. This is one of the great characteristics of the present
invention.
According to the present invention, the spinning is effected at a
temperature of from 200.degree. to 350.degree.C., preferably from
240.degree. to 300.degree.C. As the spinneret, one forming the two
components into the side-by-side type or one forming them into the
eccentric sheath-core type may be used. However, the use of
side-by-side type spinneret is preferred in view of the crimping
characteristics of the resulting filaments. The weight ratio of the
two components in the filament is variable within the range of from
10:90 to 90:10, but favorable results can be attained when the
weight ratio is between 30:70 and 70:30.
In the present invention, the drawing is effected in the same
manner as in the conventional method. That is, any of cold drawing
and hot-drawing may be adopted. The drawing ratio varies depending
on the take up velocity but is ordinarily from 2 to 9 times.
The preparation of block copolymer having different MFI value may
be effected, as mentioned before, by selection and combination of
the depolymerization degree, intrinsic viscosity and percentage of
n-heptane extraction residue of crystalline polypropylene; the
olefin component, mole % of olefin content, depolymerization
degree, intrinsic viscosity and percentage of n-heptane extraction
residue; and spinning conditions such as spinning temperature,
cooling conditions, take up velocity and denier of single
filament.
The heat treatment to fix the developed crimps and the heat
treatment to develop crimps from latent type composite filaments
are effected at temperatures in the range of from 60.degree.C. to a
temperature 10.degree.C. lower than the melting point of the
copolymer component employed. The heat treatment is preferably
performed by use of steam at 90.degree. - 120.degree.C. or hot
water at 90.degree. - 95.degree.C. For the heat treatment, a
treating time of from 5 to 60 minutes is sufficient.
It will be clear from the above illustration that in accordance
with the present invention, not only composite filament yarns but
also composite staple fibers can be produced. It is a great
characteristic in quality of the composite filaments obtained
according to the present invention that the composite filaments of
the latent type, are excellent in crimp-developing force.
The crimp-developing force referred to is defined, for convenience,
as follows:
A piece of the drawn filament obtained is treated with boiling
water under a load of 4.0 mg/denier. Subsequently, the filament is
taken out of the boiling water is subjected to a load of 50
mg/denier in place of the load of 4.0 mg/denier, and the length L
of the filament is measured. Thereafter, said load is changed to a
load of 1 mg/denier and the length S of the filament in this state
is measured. The crimp-developing force is computed according to
the following equation:
Crimp-developing force (%) = L - S/S .times. 100.
Composite polypropylene filaments according to the conventional
methods have a crimp-developing force of less than about 5% and
scarcely develop crimps. In contrast thereto, the composite
filaments in accordance with the present invention show a crimp
developing force of more than 15% in the case of 15 denier
monofilament yarn and develop excellent crimps.
The latent type composite filaments of the present invention are as
easy as in the case of the ordinary filament yarns in handling at
the secondary processing stage such as knitting or weaving, and are
far more excellent than the sensitive type crimpable filaments. It
is therefore a great effect of the present invention that such
latent type composite filaments, which are marked in
crimp-developing force and are high in industrial value, can be
obtained with ease.
The crimps of composite polypropylene filaments according to the
conventional method have suffered from such a drawback that the
crimps of the filaments are easily straightened by application of a
relatively small force, whereas the composite filaments of the
present invention have such a great advantage that they can
withstand against a relatively large force.
It is an important feature of the composite filaments of the
present invention that the two components employed are markedly
excellent in adhesion and that the crimped yarns obtained therefrom
are favorable in hand.
The present invention will be illustrated further in detail with
reference to the following examples:
EXAMPLE 1
Propylene was continuously polymerized, with addition of a small
amount of hydrogen, in n-hexane in the presence of a catalyst
comprising TiCl.sub.3 and Al(Et).sub.2 Cl, and the resulting
polymer was purified. The thus obtained crystalline polypropylene
was in the form of a powder and had an intrinsic viscosity of 2.50
and a n-heptane extraction residue of 96.1% . This crystalline
polypropylene was incorporated with 0.1% of Ionol as a stabilizer
and was subjected to a pelletizer to form pellets having an
intrinsic viscosity of 1.80. This pellet was used as one component
of spinning material.
On the other hand, propylene containing 7 mole % of ethylene was
continuously polymerized in n-hexane in the presence of the
aforesaid catalyst, and the resulting polymer was purified. The
thus obtained crystalline ethylene-propylene landom copolymer was
in the form of a powder and had an intrinsic viscosity of 12, a
n-heptane extraction residue of 85% and a melting point of
150.degree.C. This crystalline ethylene-propylene copolymer was
incorporated with 0.1% of dibutyltin maleate and was subjected to a
pelletizer to obtain pellets. The thus obtained pellet was further
incorporated with 0.1% of Ionol and was again subjected to a
pelletizer to form a pellet having an intrinsic viscosity of 1.50.
This pellet was used as the other component of spinning
material.
By means of a conjugate-spinning apparatus provided with a
side-by-side type conjugate-spinning spinneret having one orifice
of 0.5 mm in diameter, the above two starting pellets were extruded
in equal volume at a spinneret temperature of 280.degree.C., and
the resulting filament was taken up at a velocity of 200 m/min. to
obtain an undrawn composite filament of 105 denier/1 filament.
Using an ordinary drawtwister, the undrawn composite filament was
hot-drawn under the conditions of a hot plate temperature of
90.degree.C., a drawing ratio of 5.5 times and a drawing velocity
of 114 m/min. The drawn filament developed no crimps at all even
when it had been released from the bobbin and relaxed. The drawn
filament was treated in boiling water for 30 minutes under no
tension to obtain a beautiful crimped yarn having 370 crimps per 25
mm and a crimp elongation of 180%. The crimp-developing force of
the drawn filament was 40%.
The crimp elongation was measured in the following manners:
The crimped filament obtained was subjected to an initial load of 1
mg/denier and the length S' of the yarn was measured. Subsequently,
the filament was subjected to a load of 50 mg/denier and the length
L' of the filament was measured. The crimp elongation was
calculated as follows:
Crimp elongation (%) = L' - S'/S' .times. 100
EXAMPLE 2
Propylene containing 5 mole % of butene-1 was copolymerized
according to the same procedure as adopted for the preparation of
the copolymer of Example 1. The resulting powdery crystalline
butene-propylene copolymer had an intrinsic viscosity of 13 and a
n-heptane extraction residue of 83%. This butene-propylene
copolymer was treated in the same manners as in Example 1 to form
pellets having an intrinsic viscosity of 1.60.
The above pellet and the polypropylene pellet having an intrinsic
viscosity of 1.80, which had been used in Example 1, was
incorporated, respectively, with 1.5% of nickel stearate to prepare
two spinning materials.
The two spinning materials were spun and drawn in the same manners
as in Example 1, except that the spinneret temperature adopted was
270.degree.C., the drawing ratio 4.5 times and the hot plate
temperature 60.degree.C., to obtain a drawn filament of 15 denier/1
filament. This drawn filament did not develop any substantial
crimps, even when relaxed. The drawn filament was treated under no
tension in boiling water for 30 minutes to obtain a beautiful
crimped filament having a crimp elongation of 120%. The above drawn
filament had a crimp-developing force of 32%.
EXAMPLE 3
The crystalline polypropylene pellet obtained in Example 1 was used
as one spinning material. The pellet had an MFI of 13.5.
On the other hand, propylene incorporated with a small amount of
hydrogen was polymerized for 10 minutes in n-hexane in the presence
of the aforesaid catalyst. After purging the system with nitrogen
for 2 minutes, ethylene was fed for 2 minutes. Subsequently, after
purging the system with nitrogen for 1 minute, propylene
incorporated with a small amount of hydrogen was again polymerized
for 10 minutes. The above operations were repeated to effect
continuous polymerization. The resulting polymer was purified with
hydrochloric acid-containing methanol. The thus obtained powdery
crystalline ethylene-propylene block copolymer had an intrinsic
viscosity of 2.00 and a n-heptane extraction residue of 95%.
According to infrared analysis, the copolymer had an ethylene
content of 10.2 mole %. This copolymer was incorporated with 0.1%
of Ionol and was subjected to a pelletizer to obtain pellets having
an intrinsic viscosity of 1.60 and an MFI of 16.1. This pellet was
used as the other spinning material.
Using a conjugate-spinning apparatus provided with a side-by-side
conjugate-spinning spinneret having one orifice of 0.5 mm in
diameter, the above two spinning materials were extruded in equal
volume at a spinneret temperature of 280.degree.C., and the
resulting filament was taken up at a velocity of 200 m/min. to
obtain an undrawn composite filament of 105 denier/1 filament. By
means of an ordinary drawtwister, the composite filament was
hotdrawn under the conditions of a hot plate temperature of
90.degree.C., a drawing ratio of 5.5 times and a drawing velocity
of 200 m/min. The drawn filament developed no crimps at all even
when released from the bobbin and relaxed. The drawn filament was
treated under no tension for 30 minutes in boiling water to obtain
a crimped filament having 22 crimps per 25 mm and a crimp
elongation of 13.8%. The drawn filament had a crimp-developing
force of 38%.
EXAMPLE 4
The polypropylene prepared in Example 1 was used as one component
of composite filament.
On the other hand, propylene was polymerized for 15 minutes in
n-hexane in the presence of the same catalyst as in Example 1.
Thereafter, the feeding of propylene was discontinued and a mixture
of 60 mole % of propylene and 40 mole % of ethylene was immediately
fed for 2 minutes. Subsequently, propylene was again fed for 15
minutes. The above operations were repeated to effect continuous
polymerization, and the resulting polymer was purified. The thus
obtained powdery crystalline ethylenepropylene block copolymer had
an intrinsic viscosity of 14.0 and a n-heptane extraction residue
of 83%. According to infrared analysis, the copolymer had an
ethylene content of 8.0 mole %. This crystalline ethylenepropylene
block copolymer was incorporated with 0.1% of dibutyltin maleate
and was subjected to a pelletizer to form pellets. The pellet was
further incorporated with 0.1% of Ionol as a heat stabilizer and
was again subjected to a pelletizer to obtain pellets having an
intrinsic viscosity of 1.75 and an MFI of 5.3. This pellet was used
as the other component of composite filament.
Using a conjugate-spinning apparatus provided with a side-by-side
type conjugate-spinning spinneret having one orifice of 0.5 mm in
diameter, the above two components were extruded in equal amount at
a spinneret temperature of 295.degree.C., and the resulting
filaments were taken up at a velocity of 300 m/min. The thus
obtained undrawn composite filament of 300 denier/1 filament was
subjected to a drawtwister and was drawn on a hot plate at
120.degree.C. under the conditions of a drawing ratio of 5.0 times
and a drawing velocity of 130 m/min. The drawn filament was
released from the bobbin but developed no crimps. This drawn
filament was treated under non-tensioned state for 10 minutes in
boiling water to obtain a crimped filament having 11 crimps per 25
mm. and a crimp elongation of 120%. The crimp-developing force of
the drawn filament was 42%.
* * * * *