Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITLE
AROMATIC POLYAMIDE FI~ERS AND PROCESSES
FOR MA~ING SUCH FIBERS
l~ACKGROUND OF THE INVENTION
F I ELD OF TH_ I NVEN~ I ON
~he field of art to which this invention
pertain6 16 aromatic polyamide fiber~ and, ~ore
particularly, it is directed to proce6ses for making
6uch fibers.
Specifically, such invention i6 a proces6 for
dyelng a fiber 6tructure of poly(meta-phenylene
isophthalamide) fiber~ with a water-soluble dye by
heating the amorphous, water-~wollen fiber6, as 6pun
and prior to drying, with steam at a temperature from
about 110C to 140C, and preferably at about 120C,
for a ti~e ~ufficient to diffuse 6ubstantially all of
the dye into the minute pore~ in the fibers, throughout
the fiber 6tructure.
An organic water-insoluble material, ~uch a~
; 25 an ultraviolet light Ecreener, may al~o be mixed with
the watec-601uble dye and padded onto the water-~wollen
fiber6 prior to heating. While the dye i6 effectively
diffu6ed into the fiber 6tructure at temperatures
between 110C and lqOC, 6uch 6tructure must also be
heatcd with 6team at a 6ublimation temper~ture below
the gla6~ tran6ition temperature of the fiber~ in order
to 6ublime the 6creener into the pore6 of the fiber6.
The fiber6 are then, preferably, further heated with
tea~ at about 165C for a time 6ufficient to collap6e
HT-2620-B
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the pores in the fibers and lock the dye therein. At
this temperature the fibers also will crystallize and
the fiber structure is thereby stabilized against
progressive laundry shrinkage.
Various water-insoluble materials, including
disperse dyes, may be driven into the fibers in this
manner (e.~., by contacting the water-swollen,
never-dried fibers with a dispersion containing the dye
and heating with steam to 165C). Preferably thi6
sublimation step follows the diffusion step previously
described.
Description of the Related Art
Aromatic polyamide fibers are well known to
the ~rt. They have high tensile strength, are flame and
heat resistant, possess good flex life, and have very
high melting points, etc. which make them particularly
suited to be formed into fabrics usable as protective
clothing, and for many other uses.
It further is known that while aro~atic
polyamide fibers possess many desired properties as
manufactured they also require, for given uses, that
various fiteps be taken to improve a property or
properties of the fibers to meet a specific end use.
As an example, various additives such as dyes,
ultraviolet light screeners, flame retardants,
antistatic agents or water repellents, may be
incorporated into the fibers during basic manufacture
or in subsequent processing steps to improve their
performance levels.
This invention is specifically directed to
aromatic polyamide fibers of a poly(meta-phenylene
isophthalamide) polymer, hereinafter referred to as
"MPD-I fibersn. Such fibers, which are described in
greater detail in U. S. Patent 3,287,324 to Sweeny,
for example, possess many useful properties. It is
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well known to the art, however, that these fibers are
very difficult to dye.
variou~ techniques have evolved to solve this
dyeing problem. A typical solution, well known to the
art and widely practiced, dyes the fibers in an aqueous
bath in the presence of a carrier, such as
acetophenone. While this is an acceptable method for
dyeing such fibers, the carrier is expensive and must
be disposed of.
Another solùtion i5 shown in sriti~h Patent
1,438,067 to Moùlds and vance which teaches imbibing a
polyoxyethylene laurate impregnant into never-dried
MPD-I fibers by passing such fibers through an aqueous
bath, prior to dyeing. The impregnant serves as a
"structure prop" which prevents collapse of the
water-6wollen fibers on drying. The dried impregnated
fibers may subsequently readily be tinted in an
aqueous dye bath while corresponding fibers dried
without the impregnant may be tinted only under much
more vigorous conditions, including necessarily the use
of dye carrier6, such as acetophenone, as mentioned
hereinabove.
This invention solves these and other
problem6 found in the prior art by 6urprisingly finding
that by heating a6-6pun, never-dried, water-swollen
MPD-I fiber6 with 6team, heated within ccrtain
temperature ranges, it is po66ible effectively to dye
the fibers. Specifically, it has been found that 6uch
fiber6 may be dyed, using a water-601uble dye, by
heating the fibers with steam heated at a te~perature
from about 110C to 140C for a time ~ufficient to
diffuse the dye into the pore6 of the fibers.
It further has been found that after this
diffusion 6tep ha6 taken place that such fibers ~ay be
6ubsequently heated, again with steam, at a
temperature of about 165C to collapse the fibers and
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lock the dye in place. This latter step will al~o, it
has been found, crystallize the fibers and stabilize
them against progressive laundry shrinkage.
In addition, various organic water-insoluble
materials, such as ultraviolet light screeners, may be
mixed with the water-soluble dye and driven, by a
sublimation heating step, into the fiber pores.
Again, heating is accomplished with steam, while the
pores remain open and sublimation temperatures from
about 110C to 150C are required to subli~e the
water-insoluble materials into the open pores.
Accordingly, this invention provides improved
processes for making aromatic polyamide fibers, using
steam in all cases as a key step, to dye a
water-swollen fiber structure of poly(meta-phenylene
lS isophthalamide) fibers with a water-soluble dye,
before they are dried, or to add an organic
water-insoluble material to the fibers, either mixed
with the dye or alone, and to lock the dye and/or
other impregnant into the pores of the fibers. This
is accomplished by using critical steam temperatures
(e.g., 110C to 140C) to diffuse the dye into the
fiber pores and up to 165C to sublime the
water-insoluble material into such pores. At this
latter temperature the dye is also locked into the
fibers, while stabilizing such fiber~ against
proqressive laundry shrinkage. These processes give to
the fiber-making and dyeing arts a highly sought
capability, and a practical means of solving a number
of problems long challenging such arts.
Summary of the Invention
Briefly described, this invention is a
process for making synthetic fibers including the steps
of:
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extruding a solution of poly(meta-phenylene
isophthalamide) and a solvent through orifices in a
spinneret to form amorphous fibers which together
define a fiber structure, such fibers having minute
pores therein,
moving such amorphous fibers into contact
with an aqueous extraction bath to remove the solvent
during which such fibers become water-~wollen,
contacting such water-swollen fibers with an
aqueous solution containing a water-soluble material
and
heating the water-swollen fibers with steam
at a temperature from about 110C to 140C for a time
sufficient to diffuse substantially all of the
water-soluble material into the pores of the fibers
throughout such fiber structure.
Preferably the water-swollen fibers are
heated with steam at a temperature of about 120C for a
time sufficient to diffuse substantially all of the
water-soluble material into the pores of the fibers
throughout such fiber structure.
The water-soluble material diffused into the
fibers preferably is a dye. It may also be a
surfactant, for example, in which case the fiber
structure is dried after diffusion. Other
water-soluble organic or inorganic salts may be used.
Water-~oluble nonionic organic compounds or
water-soluble resins may also be diffused into the
fibers.
In a preferred embodiment, when the material
is dyed, the water-swollen, dye-containinq fibers are
then further heated with steam at a temperature above
the glass transition temperature of the fibers for a
time sufficient to collapse the pores and irreversibly
lock the dye within the fibers and to crystallize such
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fibers and stabilize them against progressive laundry
shrinkage.
In the step of locking the water-soluble
material or dye into the fibers, the fibers ~ay be
heated with steam at a temperature from about 150c to
165C and preferably are heated with steam at a
temperature of about 165C.
In another embodiment, this invention is a
process for making synthetic fibers including the
following steps:
extruding a solution of poly(meta-phenylene
isophthalamide) and a solvent throuqh orifices in a
spinneret to form amorphous fibers which together
define a fiber structure, such fibers having minute
pores therein,
moving such amorphous fibers into contact
with an aqueous extraction bath to remove the solvent
during which such fibers become water-swollen,
contacting such water-swollen fibers with an
aqueous mixture containing a water-soluble dye and an
organic water-insoluble material which sublimes in
~team at a temperature below the glass transition
temperature of the fibers,
heating the water-swollen fibers with steam
at a temperature from about 110C to 140C for a time
sufficient to diffuse substantially all of the
water-soluble dye into the pores of such fibers
throughout the fiber structure,
heating the water-swollen fibers with steam
at a sublimation temperature below the glass transition
temperature of the fibers for a time sufficient to
sublime the water-insoluble material into the pores of
such fibers throughout the fiber structure, and
thereafter,
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heating the water-swollen fibers with 6team
at a temperature above the glass transition temperature
of the fibers for a time sufficient to collapse the
pores and irreversibly loc~ the dye within the fibers
and to stabilize the fibers against progressive laundry
shrinkage.
Preferably, in this process, the
water-swollen fibers are heated with steam at a
sublimation temperature from about 110C to 150C.
In this process the water-insoluble material
may be an ultraviolet light screener or a disperse dye,
for example. After the screener or disperse dye has
been sublimed into the open pores of the water-swollen
fibers, such fibers preferably are heated with steam
at a temperature of about 165C. to close the pores
and lock the dye therein.
This invention offers improvements over the
prior art by providing processes for diffusing and
subliming watèr-soluble and water-insoluble materials,
such as dyes, into never-dried, water-swollen aromatic
polyamide fibers, using steam heated within critical
temperature ranges. These fibers are typically dyed
after drying. This invention gives to the art a novel
process for dyeing, or incorporating both
water-soluble or water-insoluble materials into these
fibers, prior to drying, using only pressurized steam
as the tran~fer means. In so doing, it provides the
art an easy-to-use, effective method of accomplishing
this objective.
Description of the Preferred Embodiments
This invention is an improved process for
making aromatic polyamide fibers.
More specifically, in the processes of this
invention, a water-soluble material, and, if desired, a
water-insoluble material are diffused or sublimed into
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a fiber ctructure of MPD-~ amorphouc synthetic fiberc
to improve their properties. During the diffucion and
sublimation step6, the fibers are water-swollen, with
open pores. Steam, at critical temperatures, i~ uced
to perfect the process.
Briefly, tbe fibers of this invention ~re
prepared from aromatic polyamide polymers such a8 are
disclosed in U.S. Patent 3,063,966 to Rwolek, Morgan
and Sorenson; 3,094,511 to Hill, ~wolek and Sweeny; and
3,287,324 to Sweeny, for example.
In the present invention, the term ~aromatic
polyamide~ ~ean6 a cynthetic polymeric ~ateri~l of
sufficiently high ~olecul~r weight to be
fiber-forming, and choracterized predominantly by the
recurring 6tructural unit
R Rl O
Il I .. ..
- N - Arl- N - C - A'2 - C -
wherein each Rl independently is hydrogen or lower
alkyl ~nd wherein Arl and ~r2 ~ay be the sa~e or
different ~nd ~ay be an unsubstituted divalent
aromatic radical or a sub6tituted divalent aro~atic
radical, the chain-extending bond6 of these divalent
aro~atic radical6 being oriented predominantly eta to
one ~nother ~nd ~he cubstituentc attached to any
aromatic nucleuc being one or ore or a Dixture of
lower alkyl, lower alkoxy, halogen, nitro, lower
carbalkoxy, or other group which do not for~ a
polya~ide during poly~erization. These poly~ers oay
be prepared by following the teachingc of U.S. ~atents
3,094,511; 3,2B7,324 or 3,063,966 ~entioned above.
A preferred aro~atic polya~ide is
poly(-etaphenylene isophthal~ide).
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In preparing the basic untreatedwater-swollen MPD-I fibers forming a part of this
invention, aromatic polyamides which have been prepared
by procedures shown in the above-mentioned patents are
combined with various solvents such as
dimethylacetamide to form a spinning solution as shown,
for example, in U.S. Patent 3,063,966 and the fibers or
filaments are formed by extruding the spinning solution
through orifices in a spinneret. Such fibers may be
dry-spun or wet-spun to form a water-swollen fiber
structure. In either case, the fibers as spun are
substantially amorphous.
"Dry-spinning" refers to a process in which
the spinning solution is extruded in the form of thin
~treams into a heated cell wherein sufficient solvent
is caused to evaporate so that the streams are
converted into individual filaments which are "dry"
enough even though still containing appreciable
quantities of residual solvent that they are
self-supporting. "Wet-spinning" involves a process
wherein the polymer spinning solution exits in the
form of thin streams which are generated within, or
are conducted into, a liquid coaqulating bath which
causes the polymer to precipitate in the form of
self-supporting filaments which may be conducted out
of the coagulating bath, and commonly also through
subsequent processing steps. Depending on the
composition of the coagulating bath, the temperature
and time of contact of the filaments with the bath,
the filaments may still retain an appreciable quantity
of the original polymer solvent at the time they exit
the bath.
As just stated the fibers whether dry-spun or
wet-spun contain a substantial amount of solvent after
having been solidified in a dry-spinning evaporation
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cell or coagulated in a wet-spinning precipitation
bath. ~o remove the solvent such fibers are brought
into contact with an aqueous extraction bath, as is
known in the art. As a result the fibers become
"water-swollen" with a water content of 35% or more.
The above-described steps of forming
amorphous water-swollen fibers of an aromatic polyamide
polymer are known to the art and these fibers are all
suitable for being further treated or processed in
accordance with the process of this invention.
Specifically, in a preferred process, these
water swollen fibers, which have not been dried, are
contacted with an a~ueous solution containing a
water-soluble material and heated with steam at a
temperature from about 110C to 140C for a time
sufficient to diffuse substantially all of the
water-soluble material into the pores of the fibers
throughout such fiber structure. The material
diffused into the fibers preferably is a dye. It may
also be a surfactant.
In another preferred embodiment, when the
material is dyed, the water-swollen, dye-containing
fibers are then further heated with steam at a
temperature above the glass transition temperature of
the fibers for a time sufficient to collapse the pores
and irreversibly lock the dye within the fibers and to
crystallize such fibers and stabilize them against
progressive laundry shrinkage. Temperatures in the
range from 150C to 165C will accomplish these
objectives.
In still another embodiment, never-dried,
amorphous MPD-I fibers of the type described are
contacted with an aqueous mixture containing both a
water-soluble material, such as a dye, and an organic
water-insoluble material which sublimes in steam at a
1 1
temperature below the glass transition temperaturo o~
the fibers. The water-swollen fibers are then heated
with steam at a temperature from about 110C to 140c
for a time suficient to diffuse substantially all
of the water-soluble dye into the pores of such fibers
and at a sublimation temperature below the gla6s
transition temperature of the fibers to 6ublime the
water-insoluble material into the open pores of such
fibers. The term "organic water-insoluble material
which subli~es in steam~, as used herein, refers to a
member of the class of water-insoluble organic
materials which are activated by steam to migrate from
the surface of the fibers into the pores of the fibers,
and the term ~sublimation temperature" refers to the
temperature at which the material is so activated to
migrate. After the diffusion and sublimation 6teps
have been completed, the fibers may be further heated
with steam at a temperature above the glass transition
temperature of the fibers for a time sufficient to
collapse the pores and irreversibly lock the material
within the fibers and to stabilize the fibers against
progre6sive laundry shrinkage.
Briefly described, the glass transition
temperature (Tg) of a polymeric fiber is a
characteri6tic of the amorphous phase of the polymer of
which the fiber i6 made. ~elow the glas6 transition
temperature, which is a relatively narrow te-perature
range rather than a sharply defined temperature, the
fiber tend6 to remain in the 6ame structural
configuration in which it was originally formed. Above
the gla6s transition temperature, the fiber readily
undergoe6 ~uch changes in 6tructure a6 relaxation of
6tresses, collap6e of pores within the fiber, and
cry6tallization of the polymer of which the fiber is
made. For poly(meta-phenylene isophthalamide) in
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12
saturated steam, the glass transition temperature is
about 150C. When a surfactant is diffused into a
fiber of poly(meta-phenylene isophthalamide), the glass
transition temperature of the fiber is affected.
The term "fiber", as used herein, includes
both staple fibers and continuous filaments. The
continuous filaments may be in the form of a tow
containing a large number of filaments or in the form
of a yarn.
The drawing is a schematic view showing key
components of an apparatus suitable for practicing the
process of this invention, which now will be described
iQ greater detail.
Referring to the drawing, a fiber structure
of never-dried, water-swollen fibers, as spun, in large
bundles called tow, as indicated by the reference
numeral 1, is supplied from a supply source 2 and
passed over guide rolls 3 to nip rolls 4 and 4~.
An aqueous bath 5 of constant level is
maintained at the entrance to the nip rolls. ~he tow 1
of water-6wollen fibers is brought into contact with
the bath S which contains the material ~e.g., a
water-soluble dye, or surfactant, or ultraviolet light
screener, for example) to be diffused or sublimed into
the fibrous tow. The pick-up of material on the
never-dried tow may be adjusted by suitably
controlling the speed of the tow and the pressure
applied between the nip rolls.
The tow 1 coated with the desired amount of
material is deposited on a belt 6, moving at a speed
~lower than the speed of the tow passing between the
nip roll6 4 and 4'. The tow is then withdrawn from the
moving belt 6, moved over a guide roll 7, and passed
into a steam chamber 8, which is suitably an elongated
cylindrical tube having two or more heating zones 9
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and 10 within which steam heated at different
temperatures and under appropriate pressure can be
supplied. The entrance and exit of the steam chamber
8 are suitably sealed to prevent escape of steam,
e.g., by supplying the tow to the steam cha~ber in
S folds which effectively prevents escape of the steam
from the chamber; likewise, passage of the steam at
different temperatures and pressures between zones 9
and 10 is prevented by suitable means, e.g., by
passing the tow through the chamber in folds.
The tow is heated in these zones 9 and 10 at
the required critical temperatures to diffuse the
water-soluble material and to sublime the insoluble
material into the fibers, after which such fibers may
be further heated to stablize the fiber structure
against progressive laundry shrinkage.
The processed tow is then withdrawn from the
chamber ~ by rolls 11 and 11 or other suitable means
and deposited in a container 12. The selective steam
treatment of the tow provides an MPD-I fiber having
the propertles sought in the treatment.
The following examples will further
illustrate this invention.
Example 1
A Preparation of Never-Dried Filaments of
Poly(metaphenvlene isophthalamide) (MPD-I). Filaments
of MPD-I having an inherent viscosity of 1.5 were dry
spun from a filtered solution containing 19% MPD-I,
70% dimethylacetamide (DMAc), 9% calcium chloride, and
2% water. On leaving the drying tower the as-spun
filaments were given a preliminary wash with water so
that they contained about 60% DMAc, 15% calcium
chloride, and 100-150% water, based on the weight of
dry polymer. The filaments were washed and drawn qX
at 90C. in a counter-current extraction-draw process
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in which the calcium chloride determined as chloride
content and DMAc content were reduced to about 0.1%
and 0.5%, respectively. The wet filaments were
gathered together to form a tow, a conventional
antistatic finish was applied to the tow, and the tow
was crimped in a stuffer box crimper at a temperature
of about B0C. in the presence of steam. The tow was
then collected, Ctill moist ~containing an amount of
water about equal to the weight of the dry tow), in a
plastic-lined cardboard box. The individual filaments
had a linear density of about 1.55 decitex (dtex) (1.7
dpf). The linear density of the never-dried filaments
here and elsewhere herein is based on the weight of dry
filaments.
s. Two 120-kilotex (1,100,000 denier) tows
of never-dried MPD-I filaments, prepared as de6cribed
in Part (A~ above, were creeled through the guides of a
continuous tow dyeing apparatus equipped for expo6ing
the tow to steam at selected temperatures for selected
exposure times. The tows were first fed between nip
rolls at the entrance of a 6team chamber at a rate of
20 m/min under a pressure of 203 kPa (two
atmosphere6), wherein an aqueous dye solution was
padded onto the tow 80 that the individual filaments in
the tow were coated with the 601ution. The 601ution
contained 70 g/l of C. I. (Colour Index) No. Acid ~lack
58 dye (a water-soluble dye), 100 g/l of C. I. No. Acid
~lack 218 dye (a water-soluble dye), B g/l of
cellulosic thickener, and 5 g/l of anionic surfactant,
adju6ted to a pH of 7 (adding acetic acid or caustic
60da a6 needed until the desired pH was obtained). The
pick-up of the dye 601ution on the tow was 30 wt. %.
The tow6 were then packed into the rectangular 6haped
~team chamber and carried through the chamber by a
chain moving at about 1 m/min, one tow on each side of
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the chain. The filaments coated with the solution were
exposed to steam at 120C in a first zone in the steam
chamber for two minutes and then to steam in a ~econd
zone at 165C for 5 minutes. Upon leaving the tow
chamber, the tows were washed with water. It was
observed that very good exhaustion of the dye into the
filaments was obtained, so that there was very little
dye remaininq on the surface of the filaments to be
removed in the washing step. After the tows were
washed, they were fed into a forced air dryer, wherein
their moisture level was reduced to 7% moisture.
Finish was applied to the tows at the exit of the
dryer. The tows were dyed a deep shade of gray.
The shrinkage of the tow was measured and
determined to be 2.4%.
Example 2
(A) Dye Padded on Tow; No Steam Treatment
A 120-kilotex (1,100,000 denier) tow of
never-dried MPD-I filaments, prepared as described in
part (A) of Example 1 above, was passed through the nip
rolls of a tow dyeing apparatus as in part (B) of
Example 1, wherein an aqueous dye solution was padded
onto the tow. ~he solution contained 394.4 9 (6.26
wt. %), of C. I. No. Acid Black 58 dye (a water-soluble
dye) and 5902 9 (93.74 wt. ~) water. A sample of the
tow with the dye padded on it was collected and
immediately washed with water, without any steam
treatment of the tow. It was observed that the tow was
somewhat stained by the dye, but that the tow remained
substantially undyed.
(B) Dye Padded on Tow; Tow Treated with 100C
Steam
A tow of never-dried filaments was padded
with a 6.26% agueous solution of Acid Black 58 dye as
bin part (A) of this example, after which the tow was
322~3
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passed into the steam chamber and exposed to ~team at
100C for 2 minutes. The tow was then passed out of
the steam chamber and was immediately washed with
water. It was observed that the tow was tinted by the
dye, but the shade of color was so light that the tow
remained substantially undyed.
(C) Dye Padded on Tow; Tow Treated with
110C Steam
Part (B) of this example was repeated,
except that the tow was exposed to steam at 110C for 2
minutes. When the tow was passed out of the steam
chamber and washed with water, it was observed that the
tow was dyed to a light shade of gray. In comparing
the effect of 110C steam in part (C) with the effect
of 100C steam in part (B), it was concluded that the
shade was beginning to build ac the temperature of the
steam was increased to 110C.
(D) Dye Padded on Tow; Tow Treated with
120C Steam
Part (~) of this example was repeatedl except
that the tow was exposed to steam at 120c for 2
minutes. When the tow was passed out of the steam
chamber and washed with water, it was observed that the
tow was dyed to a medium shade of gray. Also, there
was very good exhaustion of the dye into the filaments
of the tow, so that there was very little dye remaining
on the surface of the filaments to be removed in the
washing step.
(E) Dye Padded on Tow; Tow Treated with
140C Steam
Part (B) of this example was repeated, except
that the tow was exposed to steam at 140C for
2 minutes. When the tow was passed out of the steam
chamber and washed with water, it was observed that the
tow was dyed to a medium shade of gray, about the same
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17
as the shade observed in the tow prepared in part ~D)
above.
(F~ Dye Padded on Tow; Tow Treated with
165C Steam
Part (~) of this example was repeated, except
that the tow was exposed to steam at 165C for 2
minutes. When the tow was passed out of the steam
chamber and washed with water, it was observed that the
tow was dyed only to a very light shade of gray. The
exhaustion of the dye into the filaments of the tow was
poor, so that much of the dye remained on the surface
of the filaments of the tow and was removed in the
washing step.
(G) Dye Padded on Tow; Tow Treated with
120C Steam and then with 165C Steam
Part (~) of this example was repeated, except
that the tow was first exposed to steam at 120C for
2 minutes and then passed directly from the 120C steam
zone into another zone in which it was exposed to steam
at 165C for 5 minutes. When the tow was passed out of
the steam chamber and washed with water, it was
observed that the tow was dyed to a medium shade of
gray. Also, there was very good exhaustion of the dye
into the filaments of the tow, so that there was very
little dye remaining on the surface of the filaments
to be removed in the washing step.
(H) Shrinkage of the Steam-Treated Filaments
The shrinkage of filaments removed from the
steam-treated tows of the preceding parts of this
example was determined. The shrinkage values were as
follows:
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Filament of this steamAverage Shrinkage
example, part Temperature Value,
(~) 100C 5.4
(C~ 110 B.l
(D) 120 4 5
(E) 140 5.8
(F) 165 3.0
(G~ 120, then 165 1.9
Determination of filament shrinka~e. In
determining the shrinkage of the filaments in a dry
filamentary tow, at least five filaments are removed
from the tow and 50-cm ~20-in) lengths are cut from
each of the filaments removed. The exact length of
each of the cut filaments is measured while it i5 held
under very low tension, about 0.1 dtex. The cut
filaments are then heated in an oven at 285C in a
condition free to relax, after which they are allowed
to cool and their lengths are measured again while they
are held under the same low tension under which their
lengths were originally measured. The difference
between their oriqinal lengths and their final lengths,
divided by their original lengths, is multiplied by
100% to give the % shrinkage for each filament. The
result is reported as the average of the % shrinkages
of the filaments removed from the tow.
Example 3
Part (D) of Example 2 was repeated, except
that after the tow was exposed to 120C steam for 2
minutes and washed, the gray-colored tow was kept wet
and was passed again through the nip rolls of the tow
dyeing apparatus, wherein another aqueous dye solution
was padded onto the tow. The solution padded onto the
tow contained 420 g (6.20 wt. %) of C. I. No. Basic Red
29 dye (a water-soluble dye) and 635 g (93.8 wt. %) of
water. The tow with the dye padded on was passed
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into the steam chamber and exposed to steam at 120C
for 2 minutes. The tow was then passed out of the tow
dyeing apparatus and was immediately washed with
water. It was observed that the tow was dyed a medium
shade of reddish-qray, and that there was very good
exhaustion of the red dye into the filaments of the
tow, with very little of the red dye remaining on the
surface of the filaments to be washed off.
Part (G) of Example 2 was repeated, except
that after the tow was exposed to 120C steam and then
to 165C steam and washed, the gray-colored tow was
kept wet and was passed again through the nip rolls of
the tow dyeing apparatus, wherein another aqueous dye
solution was padded onto the tow. The solution was a
6.20 wt. % aqueous solution of C. I. Basic Red 29 dye,
the same aqueous dye solution used in the paragraph
just above. The tow with the aqueous dye solution
padded on was passed into the tow dyeing apparatus and
exposed to steam at 120C for 2 minutes. The tow was
then passed out of the steam chamber and was
immediately washed with water. It was observed that
the tow was still dyed a medium shade of gray, with
very little reddish shade visible in the tow. The
exhaustion of the red dye into the filaments of the
tow was very poor, with most of the red dye being
removed in the washing step.
Example 4
(A) 100C Steam Treatment of
Surfactant-Treated Tow
-
A 120-kilotex (1,100,000 denier) tow of
never-dried MPD-I filaments, prepared as described in
part (A) of Example 1 above, was passed through the nip
rolls of a tow dyeing apparatus as in part (B) of
Example 1 at the same tow speed and nip roll pressure,
wherein a 26 wt. ~ aqueous solution of
~8Z2~3
isopropylammonium dodecylbenzenesulfonate salt (mixture
of isomers), a water-soluble anionic surfactant, was
padded onto the tow. The pick-up of the anionic
surfactant solution on the tow was about 50 wt. %,
based on the dry weight of the tow. $he tow with the
5 anionic surfactant solution padded on was then passed
to the steam chamber of the tow dyeing apparatus,
wherein it was exposed to steam at 100C for 2 minutes.
The steam-treated tow was then dried in an air oven at
90-110 C. The dried tow contained about 16-17 wt. % of
the surfactant. Inspection of the tow, both as to its
tactility and as to its visual appearance, indicated
that much of the surfactant remained on the surface of
the filaments.
(B) 120C Steam Treatment of
Surfactant-Treated Tow
Part (A) of this example was repeated, except
that the tow was exposed to steam at 120C. for 2
minutes. Inspection of the tow, both as to its
tactility and as to its visual appearance, indicated
that substantially all of the surfactant had been
diffused into the filaments.
Example 5
Pre arin surfactant-containinq MPD-I staPle fibers
P 9
Two 120-kilotex (1,100,000 denier) tows of
never-dried MPD-I filaments, prepared as described in
part (A) of Example 1, were creeled through the guides
of the continuous tow dyeing apparatus described in
part (8) of Example 1, following the same general
procedure of the example, with the following
exceptions. The agueous bath contained in a pool above
the nip rolls was maintained at B0-95C and was
prepared by adding 128.4 kg (283 lbs) of a 93 wt.%
aqueous solution of isopropylammonium
dodecylbenzenesulfonate salt (mixture of isomers), a
- 1282213
21
water-soluble anionic surfactant, to 350 1 of hot
(90-95oc) water with only very mild agitation to
~inimize aeration of the solution. The calculated
concentration of the anionic surfactant was 25.4 wt.%.
~he tows were passed through the nip rolls at a cpeed
of 17 m/min and the nip roll pressue was maintained at
152 kPa (1.5 atmospheres), padding the anionic
surfactant solution onto the tow so that the individual
filaments in the tow were coated with the solution.
The tows were then packed into the rectangular shaped
steam chamber and carried through the chamber by a
chain moving at 1.3 m/min, one tow on each side of the
chain. Within the steam chamber the filaments coated
with the anionic surfactant solution were exposed to
steam at a temperature of 120C (gauge pressure about
one atmosphere) for an exposure time of approximately 6
minutes, the steam chamber being operated as a single
zone. Just prior to exiting the steam chamber, the
tows were exposed to cold water injected into the
chamber to wash off any excess surfactant. After
exiting the steam chamber the tows were continuously
transpoeted through a forced air dryer wherein the tows
were dried at 100-130C. Fiber samples taken from the
tows were analyzed for surfactant content by high
pres~ure liquid chromatography. It was determined that
the MPD-I fibers contained approximately 11.5-12.8 wt.%
of the anionic surfactant, based on the total weight of
the surfactant-containing fiber.
Forming a staple fiber blend, ~reparinq yarn, and
making fabric
A ~taple fiber blend was then prepared by
cuttinq the dried MPD-I tow, together with a dry tow of
poly(p-phenylene terephthalamide) (PPD-T) filaments to
form ~taple fibers having a cut length of 5 cm (2 in),
the proportion of MPD-I staple fibers to PPD-T staple
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~ibers being 95 to 5 by w~ight. ~he PPD-T filaments
were commercially available filaments having a modulus
of about 600,000 kg/cm2 ~about 9,000,000 p8i) and a
linear density o~ 1.65 dtex ~1.5 dpf), prepared as
described in u.s. Patent 3,767,756 to slades Savailable
as Type 29 "KevlarN*~ramid fiber from
E. I. du Pont de Nemours and company). A two-ply,
591-dtex ~20/Z cotton count~ spun yarn was then
prepared from the staple fiber blend on the cotton
system in the conventional manner. A 255 9/m2
~7.5 oz/yd2) plain weave fabric having a construction
of 18 ends/cm (45 ends/in) in the warp and 17 ends/cm
(42 ends/in) in the filling was then woven in
conventional manner from the spun yarn.
The fabric as woven, containing 9S wt.% MPD-I
fibers, was analyzed by the extraction technique. It
was determined that the MPD-I fibers contained
approximately 10.9% of the anionic surfactant.
Dyeing the fabric
The plain weave fabric was wetted out by
passing it through a 21C l700F) water bath in an open
width washer. A rope of the wet fabric was then placed
in a pressure beck, which was charged with 38C ~lC0F)
water, a nonionic polyether surfactant, and formic acid
to achieve a pH of 3.5. The temperature waC raised to
99C ~2100F) at about 1.7C/min (3or/min)~ held at 99C
(200F) for 20 minutes, and cooled to 80C (180F).
Six wt.~, based on fiber weight, of a cationic
comblnation black dye formulation (Astrazon Black R*-
New, available from Ciba-Geigy Corp.), was added to the
hot scour bath while the rope was ~aintained in motion
within the bath. The pH was read~usted to 3.5. The
bath was raised to 127C (260F) at 1.7C/min and was
held at 127C for 60 minutes. ~he bath was coolcd to
70C (160F). The dye bath was drained, and the fabric
22
* denotes trademark
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8;~i~;13
23
was rinsed with clean water for 10 ~inutes at 60C
~140F). The bath was drained, and the beck was
charged with water and 0.5 g/l acetic acid at 38c
(100F~. The temperature was raised to 70c (1600F) ~t
1.7C/min, and held at 70C for 20 minutes. The bath
was drained and the fabric was rinsed with cold water.
The fabric was dried on a tenter frame at 121C
(250F). The fabric was a deep black shade.
Example 6
Two 120-kilotex (1,100,000 denier) tows of
never-dried MPD-I filaments, prepared as described in
Part (A) of Example 1 above, were creeled through the
guides of a continuous tow dyeing apparatus equipped
for exposing the tow to steam at selected temperatures
for selected exposure ti~es. The tows were first fed
between nip rolls at the entrance of a steam chamber at
a rate of 12.5 m/min under a pressure of 203 kPa (two
atmospheres), wherein an aqueous dye mixture was padded
onto the tow so that the individual filaments in the
tow were coated with the mixture. The mixture contained
dyes, cellulosic thickener, and an anionic surfactant
in solution together with a dispersed water-insoluble
ultraviolet ( W ) light screener and had the following
composition: 86.4 g/l of C. I.(Colour Index) No. Acid
Green 60 dye (a water-soluble dye), 14.7 9/1 of C. I.
No. Acid Red 404 dye ~a water-601uble dye), ~.4 g/l of
C. I. No. Acid Orange 127 dye (a water-soluble dye), 6
g/l of ~ cellulosic thickener, 132 g/l of 40% active
2-(2'-hydroxy-S'-~ethylphenyl)benzotriazole paste
(Ciba-Geigy's "Tinuvinn*P paste, a water-insoluble Uv
light screener having a nelting point of about
129-134C), and 62.7 g/l of a water-soluble anionic
surfactant, adjusted to pH of 5 (adding acetic acid as
needed until the desired pH was obtained). The pick-up
of the dye solution on the tow was 30 wt. S. The
23
* denotes trademark
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~z8224~3
tows were then packed into the rectangular shaped steam
chamber and carried through the chamber by a chain
moving at about 1 m/min, one tow on each side of the
chain. The filaments coated with the aqueous dye
mixture were exposed to steam at 120C in a first zone
in the steam chamber for two minutes and then to steam
in a second zone at 165C for 5 minutes. Upon leaving
the tow chamber, the tows were washed with water. It
was observed that very good exhaustion of the dye into
the filaments was obtained, so that there was very
little dye remaining on the surface of the filaments to
be removed in the washing step. After the tow was
washed, it was fed into a forced air dryer, wherein its
moisture level was reduced to 7% moisture. Finish was
applied to the tow at the exit of the dryer. The tow
was dyed to a deep shade of a color desiqnated as stone
gray. This dyed fiber was designated as "Test Fibern.
The above procedure was repeated, except that
the water-insoluble UV light screener was omitted from
the aqueous dye mixture padded onto the tow. The tow
made by the cevised procedure was also dyed to the same
deep shade of stone gray color. The dyed tow made by
the revised procedure was designated as ~Control
Fiber" .
Carded staple pad samples of the Test Fiber
and the Control Fiber were exposed to W light in
accordance with the procedure described in AATCC Method
16E-1982, sub~ectively rating the samples against fixed
standards on the gray scale by assigning rating values
in half eteps in a range of 1 to 5, where the value of
5 represents no appreciable change and the value of
1 repre6ents the greatest change from the original
shade. The results were as follows:
Ratinq After Exposure Time Of:
Sample 10 20 30 qO (Hours)
Test Fiber 4 4-3 3 2
Control Fiber 4-3 3 2
24
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