Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGROUND OF THE INVENTION
This invention relates to a process for the melt-
spinning of a filamentary structure from a synthetic
polyamide polymer. More particularly, it is concerned
with an improved process for the formation of an
improved antistatic filament, yarn or the like by melt-
spinning a synthetic linear fiber-forming polyamide.
It has been suggested that the utility of synthetic
fibers could be increased and their properties, in
particular their antistatic properties, could be
improved if a polyalkylene ether of high molecular
weight is included in the polymer. More specifically, -
it is disclosed in U.S. Patent 3,475,898 to Magat and
Sharkey to use poly(ethylene-propylene)ether glycols
for this purpose. More recently, U.S. Patent 3,657,386
discloses that certain propylene oxide-ethylene oxide
copolymers based on ethylene diamine are useful in
preparation of an antistatic fiber of polyamide. It ~-
has also been suggested that the utility of synthetic
fiber of polyamide could be increased by dispersing in
the polyamide an antistatic compound which is a reaction
product of:
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CH3 CH3
H(ocH2cH2)y(ocHcH2)c \ ~ CH2CHO)a(c~2cH2o)x
CH3 N-A-N CH3
H(CC~2C~2)Z(cHcH2)d (cH2cHo)b(cH2cH2o~wH
where a, b, c, d, w, x, y and z are each a whole
number and A is a difunctional radical from a hydro-
carbon containing 1 to 13 carbon atoms, said tetrol
compound having a molecular weight between about
4,000 and about 50,000 and at least one compound
selected from the group consisting of diepoxides and
compounds which yield the following divalent radicals:
O O
~
-C-R'-C-, and
O O'
" H H "
-C-N-R'-N-C-
where R' is a difunctional radical from a hydrocarbon
- containing 1 to 30 carbon atoms. However, serious
problems were encountered in melt-spinning due to the
frequent occurrence of "nubs" in the fiber. The term
"nubs" is conventionally ~pplied and is used herein to
25- mean enlarged sections of filament no more than several
filament diameters in length. Nubs may be formed by
a foreign, non-orientable substance which interferes
with normal fiber stretch in a short section, resulting
in an enlargement. Foreign substances which are believed
to have contributed to nubs in the present instance include
charred polymer from the acting surface of the extruder
and spinnerette, and gels formed in the polymer. Gels
appear to be the chief cause, i.e., the nubs are
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probably created by non-orientable gel from cross-
linked polymer. Thermal degradation of the polymer
may be an important causative factor.
The reactions in thermal degradation of poly~lides
containing polyalkylene ether additives are not
entirely understood. It is likely that thermal
degradation produces a decomposition product which
serves to form cross-links between amide groups and
adjacent polymer chains. The decomposition reaction
proceeds slowly, finally building up a three-dimensional
network of molecules which may be called polymer gel
and which eventually reaches the stage where it forms -
an infusible coating on the walls of the reactor and ~
other equipment. - -
A serious difficulty which arises from the -formation of this polymer gel on the interior walls
is that from time to time pieces break off and get into ~
the flowing polymer stream where they produce damage -
to the spinning equipment.
The greatest difficulty, however, is caused by -polymer gel which has progr-essed to the three-dimensional
structural stage, but which has not yet reached the
stage of being infusible. This kind of polymer gel is
readily carried with the stream of flowing poly~er.
Being still molten or at least softened, it passes
1:hrough the pump and even through the filter medium
to show up either as discontinuities or as viscosity
differences in the spun filament. When these filaments
are later cold drawn, these defects may cause breaks
in the filaments which either cause the whole thread to
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break or else form nubs which go through to be counted
as quality defects in the final yarns.
SUMMARY OF THE INVENTION
It is an object of this invention to avoid the
above difficulties by minimizing gel formations in the
molten polyamide. Another object is to avoid
accumulation of polymer gel on the walls of the reactor,
in the pump, or in the filtering medium when melt-
spinning the polyamide. A further object is to improve
the uniformity and quality of filaments or fibers
formed from the molten polymer, in particular to
minimize nub formation in the filaments. Other objects
will become apparent from the disclosure and the
appended claims.
These objects are accomplished by the present
- invention which provides an improvemènt in the process
for the formation of an antistatic polyamide fiber from
a fiber-forming polyamide polymer containing about 1
percent to 12 percent by weight of an antistatic
compound which is a reactlon product of a tetrol
. compound represented by the formula:
CH3 C,H3
H(OCH2CH~)y(OCHCH ~ ~CH2CHO)a(CH2CH2O)xH
CH3 N-A-N C,H3
25 H(OCH2CH2)z(OCHCH2)d ~CH2CHO)b(CH2CH2O)WH
: .
- where a, b, c, d, ~ X, y and z are each a whole ~-
number and A is a difunctional radical from a hydrocarbon
containing 1 to 13 carbon atoms, said tetrol compound
. having a molecular weight between about 4,000 and about
50,000,and at least one compound selected from the group
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8~9
consisting of diepoxides and compounds which yield the
following di~alent radicals:
O O
.. .. .
S '-X'-C-, and
O O
~' H H "
--C--N--R '--N--C--
where R' iS a difunctional ràdical from a hydrocarbon
containing 1 to 30 carbon atoms, by extruding the molten
polymer through an orifice into a quenching medium and
thereafter stretching the resulting filaments, the
improvement comprising dissolving in the extrudate prior 1:
to extrusion at least 0.5 percent by weight, preferably
lS 0.5 to 35 percent based on the weight of the antistatic
compound, of a phenol compound of the formula: ~
~H3 CH3 .
114~0~1
~_ _ R ~ ;
~1 Rl .
where R is an alkyl hydrocarbon group containing less
than nine chrbon atoms, a~d Xl is a tertiary alkyl group
of at least four carbon atoms but not more than twelve
carbon atoms. Such compounds may be economically
prepared and give excellent results in the present - `
invention.
As stated above, the present invention relates to an
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improved antistatic fiber containing a novel antistatic
compound. The novel antistat~c compound is prepared
by reacting a tetrol compound, as described above, with
a chain-e~tender compound, for example a diepoxide, a
dicarboxylic acid or a diisocyanate, to form predominantly
branched, chain-extended polymer having a melt viscosity
of about 800 to 50,000 centipoises, preferably 1,500
to 25,000 centipoises, at 100C. Preferably, the
ethylene oxide moiety makes up 10 to 90% of the
molecular weight of the antistatic compound. The mol
ratio of chain-extender compound to tetrol compound is
preferably between about 0.7 and 1Ø
The phenol compounds useful in the present
invention are known compounds and some are commercialiy
available. The phenol compounds of the invention may be
prepared in accordance with U.S. Patent 2,818,945.
The tetrol compound which is chain-extended for use as
an antistatic additive in this invention is fully
described in U.S. 2,979,528 to Lundsted, assignor to
Wyandotte. These tetrol compounds are commercially
available as Tetronic series block copolymers having
molecular weights between 1,650 and over 26,000. This
series varies in length of poly(oxyethylene) chain
and poly(oxypropylene) chain. A 3 and 4 digit code
number indicates the molecular composition. When four
digits are employed, the first two explain the average
molecular weight of the hydrophobe (poly(oxypropylene)
branches on the alkylene-diamine). When three digits
are used only the first number serves this purpose.
The last digit of each code number represents the weight
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1~34(:i8~9
percentage of hydrophilic (poly(oxyethylene)) units to
the nearest 10%. The tetrol compounds in the examples
are described this way.
As diamines upon which the tetrols are based, in
addition to ethylene diamine, diamines of a hydrocarbon
containing 1 to 13 carbon atoms, preferably the lower
alkyl diamines, where the lower alkyl radical contains
1-6 carbon atoms, can be used.
The polyepoxy compounds can be prepared ~y the
method taught in British 793,913, Example I. The
other classes of compounds can be similarly prepared,
as in Example 10 in U.S. 3,009,884.
Typical of the acids and their esters to provide
the chain-extending difunctional radical are the dialkyl
phthalic, isophthalic or terephthalic esters, such as
dimethyl terephthalate and adipic, phthalic, terephthalic
sebacic, glutaric, pimelic, isocinchomeronic acids and
their esters.
Typical of the polyepoxy compounds which provide -
the difunctional or divalent compounds, used to chain
extend the tetrols based on diamines, are those polyepoxy
compounds described in British specification 793,915 -
to Union Carbide on page 2, line 48 to line 121.
Also useful to form chain-extending divalent
radicals are the aromatic or aliphatic diisocyanates,
having a structure OCN-R'-NCO, where Rt is defined
as above.
The antistatic fiber of this invention may also
contain conventional fiber additives such as antioxidants,
stabilizers, delusterants, dyeing assists, and colorants.
A
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819
DESCRIPTION OF THE PREFERRED EMBODIMENTS
.
The invention will now be further described in
the following specific examples which are to be
regarded sole~ as illustrative and not as restricting
the scope of the invention. Parts are by weight.
EXAMPLE 1
This example shows a method of preparing a
preferred antistatic additive. The instant chain-extended
polymer is pxepared from a tetrol compound covered by
U.S. Patent 2,9~9,528 to Lundsted, and sold commercially
as Tetronic 1504.
Three hundred grams of Tetronic 1504 (molecular
weight 12,500) ~as placed in a three-neck flask fitted
with a thermometer, stirrer, and addition funnel.
The Tetronic 1504 was stirred and heated to 100C.,
and 5.24 grams of 4,4' methylene bis (cyclohexyl) isocyanate,
~ ~ 2
OCN-C \ ~H-NCO
2 2
(molecular weight 262.4) was added dropwise to the material
in the flask. Agitation was continued for one hour at
100-105C. after the addition was completed. Then the ;
product was cooled to room temperature. It was a soft
solid having a melt viscosity of 8,300 centipoises at
100C. measured with the Brookfield viscometer. The
viscosity of the original Tetronic 1504 was 200 centipoises
at 100C.
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ExAI~qPLE ?
~ g]ass reactor e~uipped'with a heater and stirrer
'' was charged with a mixture of 1,520 grams of e-caprolactam
and 80 grams of aminocaproic acid. The mixture was
then flushed with nitrogen and was stirred and heated
to 255C. over a 1 hour period at atmospheric pressure
to produce a polymerization reaction. The heating and
stirring was continued at atmospheric pressure under
a nitrogen sweep for an additional 4 hours in order to
complete the polymerization. During the last 30 minutes
! of the polymeri~ation, 1.7 grams of 4,4'-butylidene-bis-
~6-tert. butyl m-cresol) and 48 grams of the antistatic
compound of Example 1, were added to the po~ycaproamide
and stirring was continued to thoroughly mix the additives '
throughout the polymer. Nitrogen was then admitted to
the glass reactor and a small pressure was maintained
; while the polymer was extruded from the glass reactor
in the form of a polymer ribbon. The polymer ribbon
was subsequently cooled, pelletized, washed and then
dried. The polymer was a white solid having a relative -
viscosity of about 55 to 60 as determined by a
concentration of 11 grams of polymer in 100 milliliters -'-
; of 90 percent formic acid at 25C. tASTMD-789-62T). ~ -~
' l'he polycaproamide pellets containing the
antistatic agent and phenol additive were melted at
about 285C. and then melt-extruded under a pressure
of about 1500 psig through a 16-orifi,ce spinnerette,
each of the orifices having a diameter of 0.014 inch,
to produce a 250-denier fiber. The ~iber was then
collected at about 1,000 feet ~er mi~ute and was drawn
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about 3.5 times its extruded length to produce a
70-denier yarn. For conv~nience, this yarn hereinafter
will be called Yarn A. A control yarn containing
the anti~tatic agent but no additional additive
was produced in the same manner as described above.
For convenience, this yarn hereinafter will be
called Yarn B. A second control y~rn containing no
antistatic compound and no phenol compound was
produced in the same manner as described above; for
convenience this yarn hereinafter will be called Yarn C.
Yarn A, Yarn B and Yarn C were woven into conventional
plain weave fabrics. The fabrics were cut into fabric
~ test samples having a width of 3 inches and a length
; of 9 inches. The fabric samples were tested for
their antistatic property in accordance with the -- -
general procedure described in the Technical Manual
of the American Association of Textile Ch~mists and
Colorists, 1969 edition, Volume 45, at pages 206-207.
This test procedure is entitled "~lectrostatic Clinging - -
of Fabrics: Fabric-to-Metal Test" and is numbered
AATCC 115-1969. In accordance with this test, Yarn C
showed poor antistatic properties, i.e., the average
time for fabric samples to decling from metal completely -
on their own was over 300 seconds after 5 to 25 wash
cycles. In contrast, Yarn A and Yarn B both showed
excellent antistatic properties, for example, average
- time for fabric samples to decling from metal completely
on their own was about 120 seconds after 25 wash cycles.
Yarn A, Yarn B and Yarn C were also tested for the
number of nubs per pound as shown in Example 3.
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EXAMPLE 3
This example outlines the method used for
locating, identifying and calculating the nubs per
pound in Yarn A, Yarn B and Yarn C as prepared in
Example 2. In this method a nub is defined as an
enlarged place in a filament which is no more than several
filament diameters in length. This method may be
used for either monofilament or multifilament yarns;
however, it is not applicable to most types of
crimped yarn.
In accordance with the test, the 70-denier yarn
is drawn directly from the package by means of an air ;
aspirator and is passed through an opening of known -~ -
width, specifically, 0.0030 inch in width. Such an
opening is conveniently provided by use of a ceramic
cleaner gap, which is well-known in the art. The
presence of a nub is detected when it stops the yarn
passage through the opening. The filaments are separated
and the cause of the yarn stopping identified as a nub
or as the twisted end of a broken filament. For
representative results, about 75 grams of yarn is passed
through the gap and the number of nubs counted. Table I -
below shows the results of testing on Yarn A, Yarn B
and Yarn C.
TABLE I
Determination of Nubs Per Pound
YarnNub Count Per
SamPlePound of Yarn
Yarn A 3,500
Yarn B 17,850
Yarn C 2,300
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It will be noted that polyamide yarn made without
additives had a relatively low nub count of 2,300 nubs
per pound of yarn. Addition of the antistatic compound
to the p~lyamide caused the nub count to increase to
17,850 per pound of yarn. However, the addition of the
antistatic compound plus the phenol compound of the
invention reduced the nub count to-3,500 nubs per pound
of yarn.
EXAMP~E 4
The procedure of Example 2 (Yarn A) was followed
except that the various additives were charged with the
caprolactam initially. The antistatic fiber nub count
was only 3,200 per pound of yarn.
EXAMPLE 5
The procedure of Example 2 (Yarn A) was followed
except that the antistatic additive was charged with
the caprolactam but no phenol compound was added.
The antistatic fiber had a high nub count of 16,700
nubs per pound of yarn.
EXAMPLE 6
The procedure of Example 2 (Yarn A) was followed
except that the antistatic additive was obtained from
the reaction product of Tetronic 1504 and dimethyl
terephthalate in a 1 to 0.7 mol ratio. The additive
has a melt viscosity of 1,600 centipoises at 100C.
Sixty grams of the antistatic compound was added
together with 1.13 grams of 4,4'-butylidene bis-(6-
tert. amyl m-cresol) and 6.4 grams of 50% aqueous TiO
dispersion. The fiber nub count was 3,160 per pound
of yarn.
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EXAMPLE 7
The procedure o~ Example 2 (Yarn A) was followed
except tha~ 90 grams o~ the antistat.ic additive of
Example 6~ was used together with 1 gram of 4,4'-heptylidene
bis-(6-tert. butyl m-cresol). The fiber produced had
a low nub count of 3,245 nubs per pound of yarn.
EXAMPLE 8
Polymer pellets were prepared in accordance with
Example 2 which contained 90 gr~ms antistatic agent
of Example 1 together with 2.7 grams of 4,4'-butylidene
bis-(6-tert.butyl-m-cresol), were melted at about 285C.
and then melt extruded under pressure of 1,500 psig
to a 70-orifice spinnerette, each of the orifices having
a diameter of 0.018 inch to produce a fiber having
about 4,500 denier. The fiber was collected at about
1,-000 feet per minute and was drawn at about 4 times
- the extruded length to produce yarn having a denier of
about 1125. This yarn will hereinafter be called
Yarn D. A control yarn containing no antistatic
agent or phenol additive was prepared in the same manner
as described above. This yarn will hereinafter be
called Yarn E.
The yarns were textured using a steam ~et and - -
. .
then two-plied by twisting two ends together with a
1-1/2 "S" twist. The yarns were tufted into a level
loop 20 oz. carpet at about 6.5 stitch rate, about -~
9/32 to 10/32 inch pile height, dyed and latexed.
Static buildup of the carpet was tested by measuring
the electrostatic ~oltage buildup on a person walking
with a series of steps on a piece of carpet according
'
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10~81g
to the st~ndard CRI Walk Test for static propensity
in carpets, also labeled AATCC 134-1969. Carpet was
conditioned at 70F. at 20 percent relative humidity.
Results are shown in the following Table.
Static Walk
CarPet Test
Made with Yarn D 4.9 KV
Made with Yarn E 14.1 KV ~-
The untextured yarn was also tested for nubs using
the nub count procedure of Example 3 except that the
ceramic cleaner gap used had an openlng of 0.006 inch.
The nub count of Yarn D was 108 nubs per pound while
that of Yarn E was 250 nubs per pound.
EXAMPLE 9
Ninety-four parts of polyhexamethylene adipamide
and six parts of the antistatic material of structure
of Example 1 and 0.18 parts of 4,4'-butylidene-bis-
(6-tert.butyl-m-cresolj are melt blended by mixing
the additive with the molten polyamide at about 285C.
- 20, The melt is extruded from a spinneret and the fibers
are drawn as described in Example 8. Carpet samples
prepared from this fiber ar.d tested in accordance --
with Example 8 showed a static build-up of 5.2 KV.
Discussion `~-
In additional tests it was determined that the
` molecular weight of the tetrol compound used to prepare -
- . -
the chair.-extended a~tistatic compound is preferably
between about 4,000 and about 50,000, the ethylene
oxide moieties making up about 10% to about 90% of the
30. molecular weight of said compound. Preferably, the
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1~4(~819
antistatic fiber contains from about 2~ to about 8% of
the chain-extended antistatic compound. Normally, the
chain-extended antistatic compound has a melt viscosity
of 800 to 50,000 centipoises at 100C.
By "antistatic" fiber is meant fibers that will
` pass the cling test and the shuffle test as described
in U.S. Patent 3,657,386. By "fibe.~" is meant multi-
filament yarn, monofilament, and all the known physical
forms of synthetic fibers. By ''polyamide" is meant
the polymers made by condensation of diamines with
dibasic acids or by polymerization of lactams or amino
acids, resulti~g in a synthetic resin characterized by
the recurring group -CONH-. By "ethylene oxide moiety"
is meant the portion of the hemical molecule -(C82C~O~-.
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., ' . . .
.
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