Note: Descriptions are shown in the official language in which they were submitted.
5(~5
RD--4319--A
TI TLE
METHOD FOR PRO~)UCING STAIN RESISTANT
POLYAMI DE F I E~EP~S
3ACRGROUND OF T}IE INVESNTION
S -- ~
Various ~ethods have be~n tried in the textlle
industry to provide 50il and/or ~tain resistant f$bers
or fabrics, upholstery, and carpets. These ~ethod~
include treating of the fiber~ wi~h fluorochemical
1~ compound~, ~ilicon compound~, or acrylic compound~. It
is also known that resi~tance ~o undesired dyeing can be
imparted to ~ f~ber by applying a dye-r~sist agent to a
previously dyed or undyed fiber. Many dye-re~ist ayents
including 6ulfonated naphthol- or sulfonDted phenol-
formaldehyde condensation products which work well onpolya~ide 6ubstrates are ~vailable. These condencation
products, however, have been found to have a disadvan-
tage in that ~hey yellow on a fiber substrate when
expo~ed to environmental conditions such as the presence
of N02. This problem is e6pecially noticeable in light
dye shade textile articles.
SUMMARY OF THE INVENTION
In a process for applying sulfonated naphthol-
or sulfonated phenol-form~ldehyde condens~tion products
to polyamide ~extile articles to render them ~tain
resi6tant, the improve~ent comprising applying the
condensation products ~t ~ p~ of between 1.5 and 2.5
whereby yellowing of the treated articles due to
exposure to N02 in the atmosphere is reduc~d.
DET~ILED DESCRIPTION OF THE INV~NTION
~ he present invention provides for a dra~atic
reduotion in the undesired yellowing of polyamide
t~xtile article~ containing ~ulfonated napthol- or
sulfonated phenol-formaldehyde condensation products
Ireferred to herein as "condensation products~ or
"stain-resist agents"), the yellowinq being due to
D~4319-~ exposure of the treated articles to environmen~al
S~S
conditions such as the presence of N02 in the
atm~phere.
Advantageously, when these condensation
products ~re ~pplied to dyed textile 6ubstrates they act
as resi~t agents against ~ubsequent staining by
accidental ~pills of certain foodstuffs ~uch as coffee,
red wine, and ~oft drink~. The latter often contain
dyes, such ~ Food Drug & Cosmetic (FD&C~ Red Dye No. 40.
For example, when a liquid containing FD&C Red Dye No.
0 40 i6 6pilled OfltO a polyamide 6ubstrate, it color5
(i.e., 6t~ins) the ~ub~trate to a ~ignific~nt degree;
however~ if the ~ubstrate i~ ~ir~t treated with a
stain-resist agent, then the spilled dye does not
permanently ~tain the carpet, as the undesired dye can
be rin6ed out.
Stain-resi~t agents effective with polya~ide
~ubstrate~, fro~ the class of sulfonated napthol- or
sulfonated phenol-formaldehyde conden6ation products are
described in U.S. Patent 4,501,591 and in other p~tent
and trade literature. Such stain-re~i6t agent~ are
typified by commercially availabl* products such as
Erionol~ NW ~Ciba-Geigyt, Intratex ~ N (Crompton ~
~nowles), and Mesitol~ NBS (Mob~y). These product6 are
601d in the textile trade for use a6 dye-resist agents
or as ~gent~ to improve wetfastne~s in the bath
proce66ing of textile goods and ~re recommended for uee
at ~n acidic pH range of about 4 to 6.
Polyamide ~ubstrates which have been treated
with the aforementioned ~tain-re~ist agent~, although
3~ having excellent ~tain re&istance propertie~, demon-
~trate a di~tinct disadvantage in that they yellow upon
exposure to certain environmental condition~ ~uch a6 N02
which is commonly foun~ in the atmosphere a~d i 6
especially abundant in urban areas. ~hi~ yellowing can
be severe enough to prevent u~e of the ~tain-re~ist
agents on light dye shade textile articles, which are
s~s
th~se articles where a ~tain resistance feature would be
most desirable.
The present process provide~ a method for
applying stain-resist agents to polyamide substrates so
that yellowing of these substrates is minimized. lt
inv~lves the application of the stain-re~ist ag~nt to a
polyamide textile ~ubstrate at a pH of between 1.5 and
2.5 r~ther than ~t pH value6 of 4 to 6. A~ shown by
Example 5 by applying the tain-resist agents in this
manner, the textile 6ubstrate~ are ~ignificantly m~re
protected again~t subsequent yellowinq due to exposure
to N02 in the atmosphere. In addition, the application
of the stain-resist agent~ at pH below about 2.5 re~ults
in greater ad~orption of the agent6 onto the polyamide
than occurs at higher pH ranges. Therefore, not only i~
yellowing reduced by the method of this propos~l, but
also there i6 realized an additional advantage in that
the 6tain-re6ist ~gent~ can be applied in a ~ore
efficient and cost-effective manner due to the greater
adsorption of the agents at lower pH values.
In a preferred embodiment of this invention, a
textils article (e.g., a carpet) would fir~t be dyed to
the de~ired ~hade, rinsed, and then 6aturated for a
pçriod of time (20 minute~) with a 601ution tliqu~d
ratio o~ 30:1) cont~lning ~ sulfonated naptho}- or
phenol-formaldehyde condens~tion product (to give a
final concentration of 0.3-1.0% by weight on the
article) where the solution pH is ~ and the temperature
is 170C. The article would then be rinsed and further
proces6ed as nece sary.
This invention i applicable to any polyamide
textil2 substrate. These 6ubstrates include fabric~,
upholstery and carpetsc In practice, the substrate is
treated with the stain-resi6~ agent in a bath of pH of
between 1.5 and 205. Any acid may be used to lower the
pH of the bath, however, noncorrosive acids ~uch a6
5~
6ulfamic, phosphoric, or ~itric acid are preferred. It
i5 al60 preferred that the textile articles be dyed or
pigmented prior to treatment with the stain-resist
agents. The concentration of stain-resist agent in the
treating bath and the temperature of treatment ~re not
critical. Additional fiber treat~ent compounds may be
pre~ent in the bath.
TEST METHODS
STAIN TEST
A liquid solution for staining carpets is
prepared by dis~olving FD&C Red Dye No. 40 in water at a
concentration of 0.1 g/liter~ Alternatively, a co~mer-
cially available cherry flavored ~ugar sweetencd
beverage powder containing FD&C Red Dye No. 40 i6
dissolved in water to provide a solution containing 0.1
g/liter FD&C Red Dye No. 40. A 30 ~1 a~ount of the
~taining ~olution is pl~ced in a 3" X 4" aluminum pan.
A carpet constructed from polyamide fiber is used in
this test, however, any textile ~aterial containing
polyamide fiber could be used. A 2-1/2" X 3-1/2" piece
of carpet t~ be tested i6 fully immersed face (tuft~)
down into the stai~ing solution for one hour. The
carpet ~mple i~ then removed from the staining
solution, rin6ed thorough~y with tap water, ~nd drled in
an ov~n for lS ~inutes at 212nF. ~he 6tain resi~tance
of the carpet i~ visually deter~ined by the amount of
red color imparted to the carpet by the staining
solution. ~ carpet rated as stain resis~ant has no red
color or only a slight trace of color after &t~ining and
rinsing. ~ carpet rated a~ not ~tain resistan~ has a
deep red color after 6taining and rinsing.
N02 YELLOWING T~:ST
The ~ample to be tested is exposed to 2 ppm N02
at ~ relative humidity of R3 + 5% and 104 + 9F for
24 hours (1 cycle) in a gas exposure cabinet (Model
GE-15, Atlas Devices Company, Chicago, Illinois). Color
45~
s
change i~ measured on a Macbeth~ 1500 Colorimeter
utilizing Illuminant C. The NO2 exposed sample i~
compared to an unexposed ~ample and the result i~
reported as ~b+ (yellowness) with increasinq positive
values of b corresponding to increased values of
yellowing. Carpet ~ample~ to be te~ted are placed into
a round sample holder (7/8" diameter) with the tufts
facing a glass coYer. A weight of 10 pounds i6 ~pplied
to the carpet sa~ple in the holder, pressing the tuft~
against the glass cover. The weight is conveniently
applied to the ~ample by using an AATCC Perspiration
Tester apparatus (~ee ~ATCC Test Method 15-1979) in
combination with a cylindrical piston which fit6 within
the ~ample holder. The ab+ value of the compressed
sample i5 read through the glass cover of the sampl2
holder.
AD~;ORPTION OF THE STAIN-RESIST AGENT ONTO FI~ER
Exhaustion o~ the ~tain-resist agent from the
treatment bath onto the polyamide fiber substrate is
reported as % exhaustion and determined by mea~uring the
light absorbance at a wavelength of 293 nm of the bath
before and after treat~ent.
EXAMPLE 1
A 6B filament, trilobal cro~s-~ection (1140
total denier) drawn and bulked continuous filament nylon
6,6 yarn wa~ produced by a conventional proce s. Two of
the~e yarns were plied and twisted to provide a yarn
having a balanced twist of 3.5 turn~ per inch (tpi).
~he resulting yarn was then heatset in a Superba
heatset appar~us (270F). A cut pile tufted carpet was
csnstructed from the heatset yarn to the following
~pecifications: 37 oz./6q. yd., 3/4" pile height, 3/16
gauge, 44 ~titches/4 inches. This carpet was dyed to a
light blue shade u6ing a conventional batch dye process
and dye auxiliaries (color formu}a was the follow;ng and
~2~;~50~
based on weight of carpet: 0.0022% C.I. Acid Yellow
219, 0.0021% C.I. Acid Red 361, 0.0219% C.I. Acid slue
277; pH - 6.0). After dyeing the carpet was rinsed and
then treated in a bath containing the stain-resi~t
agent, Intr~tex~ N liquid. This bath was prepared by
diluting the ~tain-resi~tant agent with water. An
amount of Intratex~ N liquid equal to 2~ of the weight
of carpet to be treated was employed and the bath
~djus~ed to a pH of Z using ~ulfamic acid (about 0.5-1.0
g/liter). The carpet was placed in the bath at a liquor
ratio of 30:1 for 20 minutes at 170~F and then rinsed.
The carpet wa~ removed rom the bath and dried at 250F.
The ~ exhaustion of the stain-resist ~gent from the bath
was ~easured to be 79%. The carpet was testsd for ~tain
re6istance by the ~ethod de~cribed ~bove and found to be
~tain resistant. Yellowing to NO2 was tested by the
method described above. The ~b+ value was 3.39.
Elimination of the stain-resi~t t~eatment resulted in a
~b+ value of 0.B5.
EXAMPLE 2 (CONTROB)
A carpet wa& prepared and treated as in Example
1, except that the pH of the treating ~ath was adjusted
to pH - 5 u~ing an ~cetic acid/sodium acetate buffer.
~he % exhau~tion was determined to be only 67%. This
wa~ ~ lower exhau~tion rate than that mea6ured when
u~ing a bath at pH ~ 2. ~he carpet was treated ~or and
found to be 6tain resistant. In the NO2 expo6ure test,
the carpet yellowed more than that of Example 1, having
a ~b+ value of 4.05.
EXAMPLE 3
A carpet was prepared and treated as in ~xample
1, except that the 6tain-re~ist agent u~ed wa~ Me~itol~
NBS powder. The treating solution wa~ prepared by
dis601ving the ~tain-resi~t agent in water to provide a
concenkration of 0.56% of the Mesitol~ NBS powder based
on weight of the carpet to be treated. The pH of the
5(~5
bath was then adjusted to pH ~ 2 with ~ulfamic acid.
The % exhaustion was measured to be 72%. The carpet was
tested for and found to be resistant to staining and
also the ~b+ value was 2.83.
I~X~MPLE q ( CONTROL )
A carpet was prepared and treated as in ~xample
3, except that the pB of the stain-resist treating
~olution was adjusted ~o pH ~ 5 using an acetic
acid/60dium acetate buffer. The % exhaustion wa~ found
to be only 61%. The carpet was treated for and found to
be stain resistant. In the No2 exposure te~t, the
carpet yellowed ~ore than that of Example 3, having a
Qb~ value of 4.17.
EXAMPLE 5
A carpet of the same construction as that of
Example 1 was put through a mock-dye bath procedure in
which the dye process wa carried out without a dye
present. Six carpet samples were then treated with
Mesitol~ ~BS by the 6ame procedure as in Example 1,
except that the pH of the treatment solutions was varied
over the range p~ ~ 2 to pH - 5. The carpet samples
were tested for their resistance to N02 yellowing by the
procedure described e3rlier, except that the 6amples
wer~ exposed for 2 cycles. The results of the N02
yellowing test were 6ummarized in Table 1 and Figure 1.
A significant lowering of the ~b+ value is seen when the
stain-resist agent is applied at pH 2.5 vs. 3Ø
4~505
TABLE 1
-
~b+ Value
P~
2.0 7-7
2.5 ~ 57
10 27
3.5 10.~5
10 67
5.0
~0
