Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND OF TIE INVENTION
Field ox the Invention
The present invention relates generally to textiles,
spinning, twisting, and twining. More particularly, the
invention relates to a crlmped, continuous nylon-6 filament.
Prior Art Background
.
In the majority ox textile products, two important
functional properties are required--viz., protection and thermal
insulation-- both of which can be satisfied by adequate bulkiness
l of the product. In general, a bulky product will have to be
made of a bulky fiber or filament, as the basic cons-tructional
element of any textile product is the fiber or filament.
As a consequence 3 a considerable e-f-Eort has been made
over the years to impart higher bulk to fibers and filaments
by texturing or crimping thereof, especially those which are
man-made, for example, from polyamides such as nylon-6. lhe
present invention is an improved crimped, continuous nylon-6
filament.
Statement ox Closest known Prlor art
2(1 L~he closest prior art of Wtl:iCh toe inventors are
aware is set :Eorth below.
1. U.S. 3,186,155, Breen, et al., disclose a
monocomponent synthetic organic filament, such as a nylon-6
filament, which has: (a) alternate and Z twist sections
throughout its length; (b) a random number of turns between
twist reversals; a a random, continuously varying angle of
twist along its length; a random number of twist reversals per
inch; at least one S turn and at leas-t one Z turn per inch
which have a twist angle averaging a-t least 5 degrees.
6 S
2. U.S. 4,~96,Z26, Martln, et al., discloses the
production of a crimped nylon-6 fllament similar to that disclosed
in Breen, et al., U.~. 3,186,155, supra. However, the Martin
process lS an integrated process, in contradistinction to that
of Breen, wherein the following steps are effected in immediate
succession: (a) melt spinning; (b) drawing the spun filaments
at a draw ratio such that the drawn filaments on leaving the
drawing stage have an extensibility of between 2~ and 35 percent;
and (c) texturing the drawn filaments at a velocity of between
800 and 3,000 meters per minute by an air jet process, the
temperature of the filaments being between 50 and 180 prior
to texturing.
3. U.S. 3,975,484, Okada, et al., discloses the
production of a crimped nylon-6 filament similar to that disclosed
in Breen, et al., U.S. 3,1867155, supra, by a process somewhat
similar to that disclosed in Martin, et al., U.S. 4,096,226, supra.
; Non-circular cross section polyamide filaments are melt spun,
allowed to cool, and treated with an oil. Thereupon the fila-
ments are passed around a feed roll havlng a peripheral speed
of more than about 200 meters per minute, passed in contact
with a heated body through a contact angle between about ~0
and 160U with the surface temperature ox the heated body main-
tained in the range of about 170U-~50O~. The filaments are
thereby subjected to one-sided heating and drawing, whereupon
they are passed through a steam jet crimper which is supplied
with steam at a temperature in the range of about Z00-350C.
4. leijin Limited, British 1,5~5,007, discloses
a nylon-6 multifila~ent yarn wherein the individual filaments
have an internal microstructure characterized by OC-type crystal-
linity in combination with -type crystallinity in a given
proportion. In partlcular, each ox the individual filaments of
the yarn has a birefringence of at minimum 0.~45, a maximum
denier of 0.8, and an x-ray diffraction intensl~y ratio
satisfying a specific equation.
None of the filamentary products described above is descril
as having no characteristic spherulltic ring structure along the
periphery of the cross section thereof when the cross section is
viewed undeT polarized light. Spherulitic rings normally
havea diffused transition to a non-spheruli~ic coTe. The depth
of the spherulitic ring varies usually from about 10 to about
l 20 .
Completely unsuggested by the prior art teachings,
the crimped nylon-6 continuous filament of the present inven-
tion shows a complete absence of a spherulitic ring structure
when the cross section thereof is viewed under polaTized light.
The result of the absence of such a spherulitic ring structure
is that the filament is more lustrous than available prior art fila-
ments under otherwise identical conditions. As a consequence,
the fiber producer may increase bulk and cover in a fibrous
structure such as a carpet without any loss ln luster.
JO SUMMARY OF 'l'HE INVENTION
In ordeT to furnish a textile fiber whlch affords
increased bulk and cover in a ibrous s~TuctuTe abricated
therefrom without any sacrifice in luster there is provided a
crimped nylon-6 continuous filament characterized by the absence
of a spherulitic ring structuTe along the periphery of the cross
section thereof when the cross section is viewed under polarized
light.
In accordance with. the specific teachings, a crimped
nylon-6 con$inuous filament is provided which has a denier of at
least 5, a modification ratio of between about 2 and 3, a tank
bulk of at least 8% and is characterized by the absence of a
spherulitic ring structure along the periphery of the cross
secti.on of the filament when the cross section is teed under
polarized light.
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Jo
265
\
BRIEF DESCRIPTION OF THE DRAWING
.
For a more complete understanding of the present
invention, including the primary object and benefits thereon
- 4a -
;5
which are set forth immediately above, reference should be made
to the Detailed description ox the Preferred Embodiments,
which is set forth below. This detailed description should be
read together with the accompanying drawlng, wherein:
FIG. 1 depicts two cross sections of crimped nylon-6
continuous filaments ox the prior art, which show a characteristic
spherulitic ring structure along the perlphery of the cross
sections; and
FIG. 2 depicts two cross sections ox crimped nylon-6
continuous filaments according to the present lnvention, which
show a complete absence of the spherulitic ring structure which
is characteristic of the prior art filaments shown in FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED E~!BODIMENTS
KefeTring now to the drawlng, FIG. 1 depicts an avail-
able crimped nylon-6 continuous filament (1) of the prior art,
which is shown in two cross sections thereof as viewed under
a microscope under polarized light. A characteristic spherulitic
ring (2) is observed along the periphery o-f the cross sections.
Also seen in the cross sections are small particles (~) o-f a
delustrant such as titanium dioxide. lhe spherulltlc rlng (2)
is comprised of a multiplicity of individual partiaL spherulites
(3), which, although not visible under orcLinary conditions,
are visible under polarized light. The fllaments depicted here
have a modiication ratio of between abou-t 2 and 3, i.e. 9 -the
configuration thereof is commonly referred to as "trilobal".
lo determine the modification ratio as well as the
presence or absence of a spherulitic ring structure, the
following procedure is employed. A filament or yarn sample
is placed in a suitable embedding agent. A thin section thereof
is then cut with a microtome. A photomicrograph of this section
is then obtained, and the modification ratio (MR) is calculated,
with the use of a template, employing the following equation:
MR = Do
D.l '
wherein Do Diameter of circumscribed circle to cross section, and
D1 Diameter of inscribed circle into cross section.
The presence or absence of any peripheral ring is determined by
visual observation of the section, under polarized lighting
(phase-contrast or dark field may also be employed); a photo-
micrograph can also be obtained under these conditions.
Depicted in FIG. 2 is one embodiment (5) of the crimped
nylon-6 continuous filament according to the present invention,
which is shown in two cross sections thereon as viewed under a
microscope under polarized light. No spherulitic ring is
observed along the periphery of the cross sections, as a (6).
Seen in the cross sections are small particles (4) of a delus-
trant such as titanium dioxide. lhe filaments depicted here
also have a modification ratio as discussed above of between
about 2 and 3, i.e., the configuration thereof is commonly
referred to as "trilobal".
To be sure, it is not necessary that delustrants
such as titanium dioxide be present in the filaments according
to the present invention. lndeed, the same advantages and
benefits over the prior art- are obtained when a filament
according to the present invention is substantially :Eree of any
delustrant. ~loreover, although a modification ratio ox bet~e~en
about 2 and 3 is advantageously employed, ~ilame!lts accordirlg
to the present invention may have other cross sectional con~igu-
rations as well, under which condltions the same aclvan~ages
and benefits over the prior art are observed. That is
to say, filaments of the present invention have a higher luster--
as determined visually or by any of many standard optical
methods known to the skilled artisan--when compared with other-
wise equivalent filaments of the prior art which have the same
level of crimp, or the same level of delustrant in an amount
which is substantially below the saturation level thereof, or
the same cross sectional configuration.
As is understood by those of swill in the art,
filaments according to the present invention whlch are
substantially free of any delustrant are considered to be very
highly lustrous. lf not as much luster is desired, one of the
S delustrants known to those of skill in the art may be employed.
lhese include no only the usual non-chromatic delustrant and
illers such as titanium dloxide, zinc sulfide, calcium
carbonate, glass particles, etc., but also delustering agents
which impart color as well. Such include organic and
inorganic pigments and dyes that are added to the molten nylon-6
polymer prior to or during extrusion and spinning, or to the
nylon-6 polymer in chip form in a dyeing operation prior to
extrusion and spinning. When titanium dioxide is employed,
it is advantageously present in an amount of not greater than
about 0.1 percent by weight.
The crimped nylon-6 continuous filament of the present
invention advantageously has a tank bulk o-f at leas-t 8 percent
and a denier of at least 5. Under these conditlons it is
especially suitable for use in the fabrication of a large
number ox textile structures desirable in -today's market. 'rank
bulk is determined by first measuring the lengch chatlge in a
skein ox fiber exposed to boiling water under two loads of appro~i-
mately 0.0003 g/dte~ ~L2) and 0.09 g/clte~ (Ll), respectively.
Tank bulk is then calculated employing -the following equation:
Bulk - L -L
L 100
~loreover, especially beneficial results aTe obtained when the
crimped nylon-6 continuous filament according to the present
invention has a modification ratio of between about 2 and 3 and
a denier of between about 5 and 25. Under these conditions, use
of the filament according to the present invention results in
carpets having outstanding characteristics.
6S
- In addition to showing no spherulitic ring structure
along the periphery of the cross section thereof when the cross
section is viewed under polarized light, a crimped nylon-6
continuous filament according to the present invention which
has a denier of at least 5 is found to have another significant
morphological characteristic, viz: the ratio of -form nylon-6
to a form nylon-6 is at least 1 to 1, and often about 3/1 to
3.5/1, as measured on non-heat treated, undyed, crimped filamentary
material. This compares with I- form to - form ratios of
about 1/3 to 1/3.5 for available prior art products under the same
conditions of treatment. However, after heat setting of the
crimped filamentary material of the present invention, the
Go - form is predominant. such a phenomenon clearly demon-
strates that a higher proportion of the entire filamentary
structure of the present invention is rearranged during heat
setting, thereby increasing heat setting efficiency over that
obtained with prior art products. To determine the crystallinity
ratios referred to above, t-he equitorial x-ray diffraction
pattern of the sample is measured and recorded continuously
between 2 values of 12 and 30. The alpha crystalline
form has a peak at 2 20.0 to 20.5, and another at 2 ~~
23.2 to 2~Ø llhe pseudo-gamma form has a slngle peak at
about 2 21.2. By visual examination of the curve, one
can determine the relative preponderance ox a particular
crystalline form. Such products according to the present
invention which have a ratio of I- form nylon-6 to cC - form
nylon-6 are especially desirable when substan-tially free of
any delustrant, or when a delustrant such as titanium dioxide
is present therein in an amount not greater than about 0.1
percent by weight. Moreover, modification ratios of between
`about 2 and 3 are highly advantageous, as is a tank bulk as
--8--
s
specified supra of at least about percent.
Any of the filaments according to the present inven-
tion may be employed in a multifilament yarn--e.g., grouped
together with other filaments according to the present
invention--which may be interlaced and/or twisted, utilizing
standard techniques well-known to those of skill in the art,
to produce carpets, upholstery, and other such textile structures
having outstanding characteristics.
The present invention, lncluding its object and benefits,
may be better understood by reference to the following illus-
trative examples:
xample 1
Nylon-6 chips having a relative viscosity of 2.69
as measured in 96-98% sulfuric acid and con-taining less than
0.01~ titaniwm dioxlde were melted in an extruder and spun at a
temperature of 265 through two spinnerettes with 99 irregular
shaped holes each at a thruput of 335 grams per minute per spin-
nerette forming two 99 filament threadlines. The spun filaments
were quenched with a crossflow of air at approximately 12C,
and were lubricated with an oil spin finish comprising a poly-
alko~ylated alcohol containing essentially no water. Ihe fibe-r
was stretch pre-tensioned 1 1/2%, pre-hea-ted to 45C, ancl stre-tched
3.25~ to a speed of 2119 meters per minute and heated to 165C.
The stretched threadlines were crlmped in a hot air te~turizer
such as tha-t in US Patent 3~908,248, and deposited onto a
rotating cooling sieve through which air was moved by means of
a vacuum. The sieve moved at a velocity ox 45 meters per minute.
The threadlines were unraveled from their plug form on the cool-
ing sieve to a speed of 1732 meters per minute established by
a cold pair of godets. The yarns were subsequen-tly interlaced
in a conventional air jet and wound up under 200 pond tension on
a double cup winder. lhere was no spherulitic ring structure
6 5
along the periphery of the cross section of the fiber when
viewed under a microscope under polarized light. Some of the
fiber produced was processed in a commercial space dyeing
operation and exhibited excellent uniformity and bulk/cover.
other fiber was commercially cabled, continuously heatset,
tufted, and dyed into an excellent residential type carpet.
The fiber exhibited physical properties common to
Bulked Continuous Filament (BCF) products including:
Luster : Excellent
Dtex : 1990
Tenacity : 2.3 g/dtex
Elongation at Break : 40%
'l'ank Bulk : 10.2%
Dyeability : Piece dyeable in Acid Red;
absence of noticeable
streaks in Ortalon Blue G
Filament Modifica-
tion Ratio : 2.5
Example 2
A procedure essentially equivalent to tha-t of
Example 1 was followed, resulting in a product having the
following characteristics:
Luster : Excellent
Dtex : 1430
Filament Modifica-
tion Ratio : 2.5
'l'ank Bulk : 11%
Ratio of form
nylon-6 to Oc-form
nylon-6 : 3.5/1
Dyeability : Piece dyeable in Acid Red;
absence of noticeable streaks
in Ortalon Blue G
After heat setting of this giber, the OC- form nylon-6 was
determined to be predominant.
-10-
In order to produce crimped nylon-6 contlnuous
filaments according to the present invention, it is necessary
to orient the fiber before allowing any moisture migration
into the fiber. This is advantageously accomplished by
employing an essentially non-aqueous spin finish, as
utilized in the examples above.
Although the present invention has been described
in detail with respect to certain preferred embodiments
thereof, it is understood by those of skill in the art that
variations and modifications in this detail may be effected ,
without any departure from the spirit and scope of the present
invention, as defined in the hereto-appended claims.
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