Oxidative afterwash treatment for non-formaldehyde durable press finishing process

A method for preventing discoloration of durable press fabrics containing cellulosic fibers that have been previously finished using a non-formaldehyde finishing agent such as glyoxal in which the fabric is treated with an oxidative afterwash solution at elevated temperature followed by neutralization, rinsing and drying. The oxidative afterwash treatment may be performed in a continuous process as part of or immediately following the durable press finishing operation, or at a later time in a totally separate process.

BACKGROUND AND SUMMARY OF THE INVENTION 
The present invention relates to a finishing process for durable press 
("wash and wear") fabrics and, more particularly, to an oxidative 
afterwash treatment for durable press fabrics containing cellulosic fibers 
which have been treated with a non-formaldehyde finishing agent. 
It is well known that untreated cellulosic fabrics, such as cotton, 
generally exhibit poor resilience in that they crease or wrinkle easily 
when crushed. They also have poor dimensional stability and relatively low 
resistance to shrinkage. In order to overcome those shortcomings, the 
textile industry has developed various finishing processes to improve the 
stability and resilience of fabrics containing cellulosic fibers. 
A known conventional method for durable press fabrics treats the fabric 
with a chemical agent that cross-links the cellulose molecules. The 
chemical reaction is carried out by heating to elevated temperatures to 
effect the "curing" or cross-linking of the finishing agent and thereby 
impart crease-resistant properties to the fabric. Many of the 
commercially-available processes employ, for example, a reactive resin 
based on formaldehyde such as dimethyloldihydroxyethyleneurea (DMDHEU), a 
formaldehyde-based resin formed from formaldehyde, glyoxal and urea. Other 
agents employing nitrogenous cellulose cross-liking agents such as 
N-methylolamides, are also used in conventional "formaldehyde-based" 
finishing operations. 
In recent years, the concern over the safety of exposure of humans to 
formaldehyde vapors has resulted in the development of certain 
non-formaldehyde finishing agents for durable press fabrics such as 
glyoxal (C.sub.2 H.sub.2 O.sub.2) and non-formaldehyde polymers based on 
glyoxal such as Sun Chemical's Permafresh ZF, and 
1,3-dimethyl-4,5-dimethoxyethyleneurea. Recent studies have shown, for 
example, that glyoxal is one of the few readily available non-nitrogenous 
cellulose cross-linking agents that exhibit the high reaction rates 
required for durable press finishing of cotton. As such, glyoxal offers an 
attractive alternative to the use of N-methylolamides which liberate 
formaldehyde vapors during fabric treatment, garment fabrication and 
apparel use. See Welch, "Glyoxal as a Formaldehyde-Free Durable Press 
Reagent for Mild Curing Applications", Textile Research Journal, March 
1983. However, the use of glyoxal on cellulose containing fabrics in the 
presence of a catalyst such as aluminum sulfate tends to cause appreciable 
fabric yellowing and high strength losses. The yellowing can be 
suppressed, but only to a limited extent, by adding ethylene glycol to the 
treating formulation to thereby reduce the presence of unreacted aldehyde 
or hemiacetal groups in the treated fabric. The addition of ethylene 
glycol also raises the durable press appearance rating of the treated 
fabric, and increases the resistance of the fabric to laundering abrasion. 
Although the use of glyoxal or glyoxal-based polymer finishing agents would 
reduce the release of formaldehyde vapors during fabric treatment and use, 
it has been found that the use of such finishes causes moderate to severe 
yellowing of finished fabrics, particularly upon prolonged storage. That 
is, fabrics treated with glyoxal will discolor with age and/or exposure to 
atmospheric contaminants upon storage. A probable explanation for the 
discoloration is that residual aldehyde and hemiacetal groups interact in 
the presence of sulfur dioxide, oxygen, ozone, oxides of nitrogen, etc. to 
produce the undesired yellowing over an extended period of time. Thus, the 
oxidation of the residual aldehydes to carboxylic acids and cleavage of 
the hemiacetals may effectively prohibit the formation of color in the 
fabric. 
It has now been found that the discoloration resulting from the use of 
non-formaldehyde permanent press finishing agents such as glyoxal, 
polymers of glyoxal and higher aldehydes, particularly the problem of 
fabric yellowing upon storage over long periods of time, may be eliminated 
through the use of an oxidative treatment of the treated fabric either 
simultaneously with or following the durable press finishing operation. 
The oxidative treatment according to the present invention restores fabric 
shade and eliminates yellowing during storage in that it exposes a moist 
finished fabric to an oxidation solution at an elevated temperature, 
followed by neutralization, rinsing, and drying operations. The oxidation 
bath is thought to react with color forming sites in the fabric, thereby 
eliminating yellowing caused by further reaction at those sites. The 
oxidative treatment may be performed either during or immediately after 
curing of the finished fabric in a continuous process, or at a later time 
as a totally separate process. The equipment necessary to carry out the 
oxidation can include various combinations of conventional washboxes, 
steamers and recouperators, so long as the fabric dwell time, oxidant 
concentration and chemical reaction are adequate to eliminate the 
undesired yellowing and tendency to discolor upon storage. 
A typical oxidation solution according to the invention consists of an 
oxidant, a stabilizer to retard degradation of the oxidant, a base to 
control the pH of the oxidative solution, a nonionic surfactant (acting as 
a wetting agent) and a chelating agent, if desired. The stabilizer and/or 
base may be optional depending on the choice of the oxidant. Specific but 
non-limiting examples of oxidants include sodium perborate, sodium 
percarbonate, sodium peroxide, hydrogen peroxide, sodium perchlorate, 
peroxyphosphates, persulfates, potassium periodate, and organic per-acids 
such as peracetic acid. The stabilizer may be any of those known to 
stabilize bleach baths such as sodium silicate, phosphates, phosphate 
esters, magnesium salts, phenols, amines, amides, free-radical scavengers 
or combinations thereof. Likewise, the base, surfactant, and chelating 
agent may be any of those commonly used in textile bleaching operations. 
A typical formulation for an aqueous oxidative afterwash solution according 
to the present invention is as follows: 
sodium percarbonate: 3-4% (by weight of entire bath) 
sodium silicate: 0.5-1% 
surfactant: 0.1% 
The fabric is exposed to the oxidation solution at a temperature between 
40.degree. and 200.degree. F. for a period of 5 seconds up to 5 minutes, 
depending on the strength (concentration) of the oxidation bath. In the 
preferred embodiment of the invention, the temperature range is between 
120.degree. to 160.degree. F. for a period of between 5 and 90 seconds. 
The fabric is then neutralized with a dilute organic acid (such as dilute 
acetic acid) rinsed in an aqueous bath, and dried. 
The process according to the invention offers a clear advantage over 
conventional durable press finishing operations in that it provides an 
efficient and safe method of obtaining a non-formaldehyde durable press 
fabric which is not discolored after finishing and which will not yellow 
or become discolored even after extended storage. 
Thus, it is an object of the present invention to provide for an efficient 
and environmentally safe method to eliminate the discoloration resulting 
from the use of non-formaldehyde durable press finishing agents on 
cellulosic fibers, particularly the yellowing which occurs upon prolonged 
storage. 
It is a further object of the present invention to provide an afterwash 
treatment which will eliminate discoloring but not effect the stability, 
resilience, durability or strength characteristics of the treated fabric. 
It is still a further object of the present invention to provide for a 
continuous oxidative afterwash treatment simultaneously with the durable 
press finishing which will eliminate discoloring and the tendency to 
discolor. 
Other features, objects and advantages of the invention will appear more 
fully from the following description of illustrated embodiments taken in 
conjunction with the appended drawings.

DETAILED DESCRIPTION OF THE DRAWINGS 
Referring to FIG. 1, fabric 10 containing cellulosic fibers has been 
previously finished with a non-formaldehyde durable press finishing agent 
such as glyoxal. The fabric may be treated in accordance with the present 
invention as follows: 
Fabric 10 (which has already been dipped in glyoxal, squeezed and predried) 
first proceeds through tentering frame 11. Upon exiting the tentering 
frame, it passes through fabric saturator 12 containing fabric rollers 12a 
into three counter-flowed washboxes, 13, 14 and 15, respectively, charged 
with an oxidative afterwash formulation in accordance with the present 
invention. The afterwash formula is mixed in saturator 12 and washboxes 
13, 14 and 15 with the necessary amounts of nonionic stabilizer and base 
(such as caustic) being added first to the nearly full washers. The 
necessary mixing may be accomplished by conventional means such as by way 
of a pipe connected to a compressed air line. The alkali concentration of 
the oxidative solution may also be checked by titration at this point and 
adjusted if necessary. In this regard, it has been found that the optimum 
pH level during the oxidative afterwash treatment in washboxes 13, 14 and 
15 should remain between 10.5 and 11.4. If the pH is above or below this 
range, the stability of the peroxide and efficiency of the process will be 
reduced. 
The required amount of oxidant (such as hydrogen peroxide) is added as 
shown generally at 16 and the entire oxidative bath is mixed to ensure a 
uniform bath concentration and temperature. Titrations may also be made 
after oxidant addition in order to monitor and adjust its concentration. 
The nonionic surfactant is added as shown at 17. Concurrently, two head 
tanks, 18 and 19, are prepared on a level above the washboxes to feed 
directly to saturator 12 to maintain a liquid level and concentration 
sufficient to complete the oxidative reaction. 
Because the oxidative reaction occurs at an elevated temperature, the 
washboxes are heated via steam jacket 20 immediately prior to running. 
Also, in order to maintain the required oxidant concentration in the 
washboxes, an electrically driven pump 21 feeds concentrated oxidant (such 
as 50% hydrogen peroxide) through a distribution manifold 22 into the 
washboxes. After exiting the last washbox, fabric 10 passes through a weft 
straightener 25 to neutralization saturator 40 to complete the oxidative 
afterwash step in accordance with the invention. 
The neutralization, rinsing and drying operations according to the 
invention are depicted in FIG. 2. Fabric 10 proceeds through a 
neutralization saturator 40 and four counter-flowed shallow washers, 41, 
42, 43 and 44, respectively. Saturator 40 is maintained at a constant 
liquid level and pH with, for example, a 2.0% acetic acid solution which 
is fed from head tank 50. The neutralization reduces the pH down to a 
level of approximately 5.0 and is done at a "cold" temperature, i.e. in 
the range of 70.degree. F. Preferably, fabric 10 is subjected to two 
consecutive dips in neutralization saturator 40. 
Following neutralization, the fabric is rinsed by passing it through the 
four counter-flowed washers, 41, 42, 43 and 44, receiving a total of 12 
dips. It then proceeds over a series of predrying cans (shown collectively 
as 60), a weft straightener 62, and onto tentering frame 63 for final 
drying. The dried, afterwashed and bleached fabric is then batched in a 
conventional manner. 
As those skilled in the art will appreciate, the processing equipment 
depicted in FIGS. 1 and 2 are not intended to be limiting but is merely 
illustrative of the basic process steps according to the invention. 
EXAMPLE I 
A trial was conducted using the processing equipment depicted in FIG. 1 to 
evaluate the feasibility of oxidative afterwashing on a typical 
non-formaldehyde finished fabric containing cellulosic fibers (65 percent 
polyester/35 percent cotton shirting). The fabric was then batched wet and 
run through an acetic acid neutralization, rinsed, and immediately dried 
on a tentering frame as depicted in FIG. 2. The fabric was, therefore, 
processed in separate operations--first, oxidative afterwashing, followed 
by neutralization, rinsing and drying. As those skilled in the art will 
appreciate, however, the process steps according to the invention may be 
carried out on a continuous basis without any interruption between the 
oxidation, neutralization, rinsing or drying steps. 
The oxidative afterwashing used the following formulation: 
1% sodium silicate* 
1% of 50% sodium hydroxide (caustic) 
3% of 50% hydrogen peroxide 
0.1% of Springscour 155 (a nonionic surfactant) 
FNT *All percentages are based on the weight of the bath ("% OWB"). 
Approximately 1300 yards of a fabric containing cellulosic fibers (65% 
polyester/35% cotton) and finished with a non-formaldehyde glyoxal finish 
formulation in a previous trial, was subjected to the following oxidative 
afterwash treatment. The finished fabric proceeded through a tentering 
frame at 60 ypm in which the drying oven temperature was approximately 
250.degree. F. at the beginning of the trial. 
After exiting the tentering frame, the fabric passed through a 197 gallon 
saturator followed by three counterflowed 353 gallon washboxes charged 
with the above afterwash formulation. At the 60 ypm speed, the residence 
time in the afterwash bath was approximately 21 seconds. The afterwash 
formula was mixed directly in the saturator and washers with necessary 
amounts of sodium silicate and caustic added to nearly full washers. The 
mixing was accomplished by using a 3/8-inch diameter, 60-inch pipe 
connected to a compressed air line. The alkali concentration was titrated 
and adjusted to a pH level between 10.5 and 11.1. The required amount of 
50% hydrogen peroxide was then added and the bath was again mixed. A 
second titration was made to determine the peroxide level and the 
concentration adjusted to comply with the desired formulation. The 
nonionic surfactant was then added to the final afterwash solution. 
As part of the after wash treatment, two 250-gallon head tanks were 
prepared on the mezzanine level above the washboxes for purposes of 
feeding directly to the saturator to maintain the necessary liquid level 
and oxidant concentration. The washers themselves were heated via a steam 
jacket to 160.degree. F. immediately prior to running the trial. In order 
to maintain the required peroxide concentration in the washers due to 
decomposition of the peroxide at elevated temperatures, an electrically 
driven pump was used to feed 50% hydrogen peroxide through a distribution 
manifold into the washers. The pump output volume was governed by a variac 
transformer and could be varied from 0.4 to 1.7 gallons per minute. 
After exiting the last washer, the fabric was batched wet to await 
neutralization, rinsing and drying. 
The neutralization, rinsing and drying steps were carried out as generally 
illustrated in FIG. 2. The batch wet fabric was passed through a saturator 
and four counterflowed shallow washers with the saturator being maintained 
at 71.degree. F. and a constant liquid level with a 2.0% acetic acid 
solution fed from a head tank. The fabric was subjected to two dips in the 
saturator with a total residence time of approximately 4 seconds at a 70 
ypm range speed. The fabric then passed through four counter-flowed 
washers receiving a total of 12 dips with a residence time through the 
washing of approximately 26 seconds. The washer temperature was maintained 
at 165.degree. F. using steam-heated plate heaters located in the washer 
walls. A patch of fabric was taken using a sampling gun following the last 
washer and tested for pH and sodium acetate concentration. No sodium 
acetate was present and the fabric pH was found to be between 6.0 and 6.5. 
The fabric was then passed through a weft straightener and onto a 
tentering frame. The frame temperature was initially 300.degree. F., but 
dropped to 250.degree. F. at the end of the run. After drying, the fabric 
was batched and tested for whiteness, shrinkage, accelerator weight loss, 
strength and durable press and then compared with a resin "control" fabric 
as set forth in Table 2 below. 
TABLE 2 
______________________________________ 
Sam- DP.sup.1 Shrinkage.sup.2 
Description 
ple 1W 5W 1W 5W.sup.4 
______________________________________ 
Glyoxal 1 3.25 3.25 .75 .times. .56 
.94 .times. .94 
2 3.50 3.25 .56 .times. .56 
1.11 .times. .94 
3 3.25 3.25 .56 .times. .56 
.94 .times. .94 
4 3.25 3.25 .83 .times. .75 
1.11 .times. .75 
5 3.50 3.33 .56 .times. .56 
.94 .times. .56 
Resin 6 3.25 3.25 .75 .times. .56+ 
.94 .times. .56+ 
Control.sup.3 
Avg. Glyoxal 
(1-5) 3.35 3.26 .65 .times. .59 
1.00 .times. .83 
______________________________________ 
Notes: 
.sup.1 Durable press rating based on average of three samples (max. = 5.0 
using test procedures adopted by the American Assn. of Textile Chemists 
and Colorists, "Appearance of Durable Press Fabrics After repeated Home 
Launderings", AATCC 124-1978. 
.sup.2 Percent shrinkage after 1 wash and 5 washings in warp and weft 
directions, respectively (acceptable ratings less than 1.0), Dimensional 
Changes in Automatic Home Laundering of Woven and Knit Fabrics, 1351978. 
.sup.3 Dimethyloldihydroxyethyleneurea (DMHEU). 
.sup.4 Number of home launderings prior to rating of property. 
Sam- AWL.sup.5 
Tensile.sup.6 
Description 
ple Whiteness.sup.4 
% (lbs) Tear (g).sup.7 
______________________________________ 
Glyoxal 1 171.12 5.89 90 .times. 51 
1800 .times. 1300 
2 175.51 6.09 91 .times. 50 
1750 .times. 1300 
3 174.14 5.52 92 .times. 48 
1750 .times. 1250 
4 176.96 6.70 92 .times. 49 
1800 .times. 1350 
5 174.89 6.04 91 .times. 50 
1850 .times. 1250 
Resin 6 184.74 3.59 82 .times. 43 
1300 .times. 850 
Control.sup.3 
Avg. Glyoxal 
(1-5) 174.52 6.05 91 .times. 50 
1790 .times. 1290 
______________________________________ 
Notes: 
.sup.4 Whiteness measured using reflectance spectrophotometer. Higher 
values represent greater whiteness. The Whitness Index value is determine 
from C.I.E. Tristimulus values were the Whiteness Index = 4Z - 3Y. 
.sup.5 Accelerator weight loss based on ASTM guidelines, "Accelerator 
Method", AATCC 931978. (an approximation of abrasion resistance of fabric 
measured before and after "tumbling" against sandpaper) 
.sup.6 Tensile strength of fabric in the warp and weft directions, 
respectively, using Instron tensile tester, "Breaking Load and Elongation 
of Fabrics", ASTM D 1962. 
.sup.7 Tear strength of fabric in grams in the warp and weft directions, 
respectively, based on Instron testing, "Tear Resistance of Woven Fabrics 
by Falling Pendulum (Elmendorf) Apparatus", ASTM D 1424. 
The results achieved during the trial in Example I also indicate that the 
afterwash formulation used in accordance with the present invention is 
heat-sensitive. For example, at the recommended operating temperature of 
160.degree. F., the hydrogen peroxide loss was found to be approximately 
1.0% per minute. FIG. 3 of the drawings shows the decomposition of 
peroxide at 160.degree. F. over time. 
Because rapid decomposition of the oxidant occurs at higher temperatures in 
a continuous process, means for providing continuous makeup of peroxide to 
the afterwash bath are necessary to maintain the required concentration 
level. In this connection, the following temperature measurements and 
chemical concentrations were recorded during Example I. 
______________________________________ 
Wash Boxes 
Time Saturator 
W.sub.1 W.sub.2 
W.sub.3 
______________________________________ 
1:30 (Time = 0).sup.1 
Temp. .degree.F. 
146 162 163 163 
Alkali %.sup.2 
1.29 -- 0.99 -- 
Peroxide % 2.97 -- 2.14 -- 
of 50% 
1:50 (20 min.) 
Temp. .degree.F. 
180 178 170 170 
Alkali, % -- -- 0.97 -- 
Peroxide % -- -- 2.48 -- 
of 50% 
2:15 (35 min.) 
Temp. .degree.F. 
173 170 169 169 
Alkali, % -- -- 0.91 -- 
Peroxide % -- -- 2.76 -- 
of 50% 
2:17 (37 min.) 
Temp. .degree.F. 
172 169 168 168 
Lot Ends Alkali, % -- -- 0.92 -- 
Peroxide % -- -- 3.42 -- 
of 50% 
______________________________________ 
Notes: 
.sup.1 Concentrations in Head Tank for Saturator at start of run: 1.41% 
Alkali, 3.66% Peroxide 
.sup.2 Percentages based on the weight of bath 
EXAMPLE II 
In order to determine whether a glyoxal-finished fabric could be 
oxidatively treated in a continuous process to yield a white, 
non-formaldehyde fabric with good durable-press properties, oxidative 
afterwash trials were also run using a wet-bottom steamer (recouperator). 
Referring to the figures, saturator 12 in FIG. 1 could, for example, be 
replaced by a wet bottom steamer. Following oxidation the fabric proceeds 
straight to the neutralization equipment (rather than to wash boxes 13, 14 
and 15) as shown in FIG. 2. In this Example, the fabrics were exposed to 
the oxidation bath in the steamer for either 30, 60, or 90 seconds at 
160.degree. F. Following oxidation, the fabrics were rinsed, neutralized, 
rinsed, dried again, and then examined for whiteness and resilience. As 
the following tables indicate, exposure times over 90 seconds have a 
detrimental effect on the durable-press properties. The specific oxidation 
conditions and physical properties of the tested fabrics are as follows. 
TABLE 3 
______________________________________ 
Oxidative Afterwash Formula 
For Example II Fabrics 
Chemical % OWB 
______________________________________ 
Silicate 1% 
Caustic 1% 
Chelating Agent.sup.1 
1% 
Hydrogen Peroxide 3% 
Operating Temperature: 
160.degree. F. 
Procedure: 
Oxidize, rinse on jig, sour with acetic acid, 
rinse, dry (250.degree. F./1 min.) 
______________________________________ 
Notes: 
.sup.1 Plexene D 
TABLE 4 
______________________________________ 
DP Shrinkage White- 
Sample 1W 5W 1W 5W % AWL ness 
______________________________________ 
Resin Control 
3.4 3.4 .0 .times. .0 
.3 .times. .0 
3.39 188 
Glyoxal 40LF.sup.1 
3.5 3.4 .0 .times. .0 
.3 .times. .0 
12.81 159 
(not oxidized) 
Glyoxal 40LF 
3.5 3.3 .6 .times. .6 
.8 .times. .6 
-- 177 
(30 sec. ox.) 
Glyoxal 40LF 
3.4 3.3 .3 .times. .4 
.6 .times. .4 
5.81 182 
(60 sec. ox.) 
Glyoxal 40LF 
3.3 3.3 .6 .times. .3 
.6 .times. .6 
5.35 178 
(90 sec. ox.) 
______________________________________ 
Notes: 
.sup.1 Commercially available glyoxalbased formula manufactured by 
American Cyanamid. 
The foregoing tables in Example II demonstrate that a glyoxal-treated 
durable-press fabric known to give good durable-press performance can be 
whitened by an afterwash in accordance with the present invention and 
still retain desirable physical properties such as low shrinkage and high 
durable press ratings. In particular, oxidative afterwashing using a 
wet-bottom steamer (recouperator) afforded a white non-formaldehyde 
finished fabric with commercially acceptable durable-press properties. In 
addition, the accelerotor weight loss was reduced by the afterwash 
treatment. 
EXAMPLE III 
Additional afterwashing trials were performed on a cellulosic fabric which 
had previously been finished with Glyoxal 40LF. Three afterwashing 
parameters were studied--temperature, time, and concentration (expressed 
as a percent of the oxidation formula). The procedure involved exposing 
fabrics to the oxidation solution for the appropriate time and 
temperature, rinsing in hot water (1 minute), souring with 2% acetic acid, 
rinsing in hot water (1 minute), and drying (250.degree. F./30 sec.). 
The afterwash formulations used and testing results are shown in Tables 5 
and 6 below. 
TABLE 5 
______________________________________ 
Chemical % OWB 
______________________________________ 
A. FINISH FORMULA 
glyoxal (40%) 12.0 
Polydimethyl siloxane 
1.5 
fluid emulsion 
Catalyst.sup.1 4.0 
Springswet 300.sup.2 
0.1 
Dry temp/time 250.degree. F./min. 
Cure temp/time 400.degree. F./20 sec. 
B. OXIDATION FORMULA 
Silicate 1.0 
Caustic 1.0 
Hydrogen Peroxide 3.0 
Springscour 155.sup.3 
0.1 
______________________________________ 
Notes: 
.sup.1 Magnesium sulfate/aluminum sulfate blend 
.sup.2 Blend of anionic and nonionic surfactants 
.sup.3 Blend of alcohol and phenol ethoxylates 
TABLE 6 
__________________________________________________________________________ 
Afterwash Conditions DP Shrinkage 
Sample 
Concentration.sup.1 
Temperature (.degree.F.) 
Time (Min) 
1 Wash 
5 Washes 
1 Wash 5 Washes 
Whiteness 
__________________________________________________________________________ 
1 Original 
(No afterwash) 3.5 3.5 .28 .times. 0 
.56 .times. 0 
135.84 
2 1 160 30 3.0+ 
3.0+ .28 .times. 0 
.56 .times. 0 
172.90 
3 1 160 15 3.0+ 
3.0+ .28 .times. 0 
.28 .times. 0 
171.44 
4 1 160 10 3.0+ 
3.0+ .28 .times. 0 
.56 .times. 0 
173.08 
5 1 160 0.5 3.5 3.5 .28 .times. 0 
.56 .times. .28 
149.48 
6 4/3 160 30 3.0+ 
3.0+ .28 .times. 0 
.28 .times. 0 
173.92 
7 4/3 160 10 3.0+ 
3.0+ .28 .times. 0 
.28 .times. 0 
172.75 
8 2/3 160 30 3.0+ 
3.0+ .56 .times. 0 
.75 .times. 0 
171.34 
9 2/3 160 10 3.0+ 
3.0+ .56 .times. 0 
.75 .times. 0 
169.43 
10 1/3 160 30 3.0+ 
3.0+ .56 .times. .28 
.56 .times. .28 
172.18 
11 1/3 160 10 3.5 3.5 .28 .times. 0 
.56 .times. 0 
165.31 
12 1 140 30 3.5 3.5 .56 .times. 0 
.75 .times. 0 
176.84 
13 1 140 10 3.5 3.5 .0 .times. 0 
.0 .times. 0 
174.10 
14 4/3 140 30 3.0+ 
3.0+ .56 .times. 0 
.75 .times. 0 
176.86 
15 4/3 140 10 3.0+ 
3.0+ .56 .times. 0 
.75 .times. 0 
175.71 
16 2/3 140 30 3.5 3.5 .56 .times. 0 
.75 .times. 0 
175.52 
17 2/3 140 10 3.0+ 
3.0+ .56 .times. 0 
.83 .times. 0 
168.45 
18 1/3 140 30 3.0+ 
3.0+ .28 .times. 0 
.56 .times. 0 
169.56 
19 1/3 140 10 3.5 3.5 .28 .times. 0 
.28 .times. 0 
162.11 
20 4/3 100 30 3.5 3.5 .28 .times. 0 
.56 .times. 0 
173.28 
21 4/3 100 10 3.0+ 
3.0+ .28 .times. 0 
.56 .times. 0 
168.93 
22 2/3 100 30 3.0+ 
3.0+ .28 .times. 0 
.56 .times. 0 
172.65 
23 2/3 100 10 3.5 3.5 .28 .times. 0 
.56 .times. 0 
167.16 
24 1/3 100 30 3.5 3.5 .28 .times. 0 
.56 .times. 0 
164.81 
25 1/3 100 10 3.5 3.5 .28 .times. 0 
.28 .times. 0 
157.20 
26 1 100 30 3.0+ 
3.0+ .56 .times. 0 
.56 .times. 0 
173.46 
27 1 100 15 3.0+ 
3.0+ .28 .times. 0 
.56 .times. 0 
171.15 
28 1 100 10 3.0+ 
3.0+ .28 .times. .28 
.28 .times. .28 
166.82 
29 1 100 5 3.0+ 
3.0+ .28 .times. 0 
.56 .times. 0 
161.08 
30 1 100 0.5 3.5 3.0+ .0 .times. 0 
.28 .times. 0 
143.18 
31 Unfinished 2.5 2.5 1.94 .times. 1.11 + 2.22 .times. 
1.11+ 178.70 
32 Resin Control.sup.2 3.0+ 
3.0+ 
.28 .times. .56 
.56 .times. .56 
175.79 
__________________________________________________________________________ 
Notes: 
.sup.1 Expressed as fraction of the given oxidation formula 
.sup.2 DMDHEU 
From the foregoing, it is clear that longer dwell times, higher 
concentrations, and higher temperatures afford whiter fabrics. Also, 
durable press results matched or exceeded those obtained on the resin 
control. 
EXAMPLE IV 
A two-part study was conducted to determine the effectiveness of batch 
afterwashing on non-formaldehyde durable press fabrics finished with 
glyoxal (40%). The first part consisted of a simulation of plant 
processing conditions where the glyoxal (40%) fabric was finished using a 
vacuum slot extraction apparatus and then afterwashed in a batch process 
using a Burlington Beck apparatus. Three fabric styles were studied 
(identifed as "S/411", "S/638", and "S/520"). The glyoxal (40%) samples 
were subjected to two sets of curing conditions (see Table 8) and then 
afterwashed according to the formula and conditions shown in Tables 7 and 
8, respectively. The test results shown in Table 9 indicate that good 
physical properties and whiteness were obtained on the afterwashed samples 
when compared to the resin control. 
The second portion of the study used different concentrations of oxidants 
to determine the required minimum level for acceptable whiteness. The 
formulations and results shown in Table 10 and the graphical 
representation of FIG. 4 indicate that whiteness values decrease sharply 
if the oxidant concentration falls below approximately 1% peroxide owb. 
TABLE 7 
______________________________________ 
Chemical % OWB 
______________________________________ 
A. FINISH FORMULATIONS 
1. Non-Formaldehyde 
Glyoxal 40LF 25.0 
polydimethylsiloxane emulsion 
3.0 
Catalyst.sup.1 8.3 
Springswet 300 0.2 
2. Resin Control 
Aerotex 901 15.0 
Softener 1442J.sup.2 
2.0 
Catalyst 135B.sup.3 
3.8 
Springswet 300 0.2 
B. AFTERWASH FORMULATION.sup.4 
(NON-FORMALDEHYDE FINISH ONLY) 
Silicate 0.2 
Caustic (50%) 0.2 
C. FABRIC DESCRIPTIONS 
S/411 - 65/35 polyester/cotton broad- 
cloth, 110 .times. 76, 45's warp end 
filling, 3.1 oz/yd.sup.2 
S/520 - 65/35 polyester/cotton 
gabardine, 108 .times. 60, 22's 
warp, 17's filling, 6.0 oz/yd.sup.2 
S/638 - 65/35 polyester/cotton broad- 
cloth, 128 .times. 72, 50's warp end 
filling, 3.0 oz/yd.sup.2 
Hydrogen Peroxide (50%) 
0.6 
Springscour 155 0.05 
______________________________________ 
Notes: 
.sup.1 Blend of magnesium sulfate and aluminum sulfate. 
.sup.2 Blend of fatty acid ethoxylates 
.sup.3 Magnesium chloride 
.sup.4 Liquor/goods weight ratio = 20:1 
TABLE 8 
______________________________________ 
Processing Parameters 
______________________________________ 
A. FINISHING: 
Speed: 50 YPM 
WPU.sup.1 : Vacuum Slot 
S/411 = 25.4% 
S/638 = 30.6% 
S/520 = 35.5% 
Drying On Cans 
Cure.sup.2 : 1 Non-Formaldehyde 
400.degree. F./20 sec. 
or 380.degree. F./40 sec. 
2. Resin Control 
400.degree. F./20 sec. 
B. AFTERWASHING (NON-FORMALDEHYDE 
ONLY USING BURLINGTON BECK) 
Oxidation: 30 minutes at 160.degree. F. 
Rinse: 5 minutes at 160.degree. F. 
Neutralization: 5 minutes at ambient 
temperature with 0.08% acetic 
acid (or until fabric is just 
acid) 
Rinse: 5 minutes at 160.degree. F. 
Dry: 250.degree. F./1 minute on frame at 44- 
45" 
______________________________________ 
Notes: 
.sup.1 Wet pickup or calculated as percent of dry fabric weight 
.sup.2 Fabric is cured in a tentering oven at 420.degree. F. for 20 
seconds to effect the crosslinking reaction 
TABLE 9 
______________________________________ 
DP.sup.1 
Shrinkage 
Style Sample 1W 5W 1W 5W 
______________________________________ 
S/411 GLY(400) 3.33 3.50 .28 .times. .28 
.56 .times. .56 
GLY(380) 3.50 3.50 .28 .times. .56 
.28 .times. .56 
GLY(400) 2 3.50 3.50 .28 .times. .28 
.56 .times. .56 
AW.sup.2 
GLY(380)AW 3.33 3.33 .28 .times. .56 
.28 .times. .56 
Resin Control 
3.25 3.25 .28 .times. .83 
.56 .times. .83 
Unfinished 2.50 2.50 1.67 .times. .0 
1.89 .times. .0 
S/638 GLY(400) 3.33 3.33 .28 .times. .28 
.56 .times. .28 
GLY(380) 3.25 3.25 .28 .times. .28 
.28 .times. .56 
GLY(400)AW 3.17 3.25 .28 .times. .28 
.56 .times. .28 
GLY(380)AW 3.25 3.25 .28 .times. .28 
.56 .times. .56 
Resin Control 
3.25 3.25 .56 .times. .28 
.56 .times. .56 
Unfinished 2.50 2.50 2.22 .times. 
2.78 .times. 
1.39+ 1.67+ 
S/520 GLY(400) 3.50 3.50 .56 .times. .83 
1.11 .times. 1.11 
GLY(380) 3.83 4.00 .56 .times. .56 
.83 .times. .83 
GLY(400)AW 3.50 3.50 .75 .times. .56 
1.39 .times. .56 
GLY(380)AW 3.67 3.83 .83 .times. .83 
1.39 .times. .83 
Resin Control 
2.67 3.67 .56 .times. .83 
.83 .times. .94 
Unfinished 2.00 2.50 2.50 .times. .56+ 
3.33 .times. .56+ 
______________________________________ 
Style Sample AWL % Whiteness 
______________________________________ 
S/411 GLY(400) 14.60 142.09 
GLY(380) 14.53 141.35 
GLY(400)AW 8.98 161.74 
GLY(380)AW 7.74 173.06 
Resin Control 
2.53 163.52 
Unfinished 0.28 190.05 
S/638 GLY(400) 14.20 147.49 
GLY(380) 13.93 147.57 
GLY(400)AW 8.94 165.40 
GLY(380)AW 8.47 162.88 
Resin Control 
2.46 186.69 
Unfinished 0.89 192.99 
S/520 GLY(400) 13.82 123.31 
GLY(380) 14.47 123.55 
GLY(400)AW 9.41 168.81 
GLY(380)AW 8.40 167.40 
Resin Control 
4.74 181.81 
Unfinished 1.65 183.35 
______________________________________ 
Notes: 
.sup.1 Average of 3 samples 
.sup.2 GLY(400) AW is interpreted as glyoxal cured at 400.degree. F. and 
given the oxidative afterwash. 
TABLE 10 
______________________________________ 
A. FORMULATIONS: 160-180.degree. F. at 20:1 
Liquor to Goods for 30 min. 
Samples 
Chemicals (% OWB) 
1 2 3 4 5 
______________________________________ 
Silicate 1.0 .33 .17 .10 -- 
Caustic (50%) 1.0 .33 .17 .10 -- 
Hydrogen Peroxide (50%) 
3.0 1.0 .50 .30 -- 
SS 155 0.1 0.1 0.1 0.1 0.1 
______________________________________ 
B. RESULTS 
Sample Whiteness 
______________________________________ 
1 173.45 
2 170.00 
3 164.83 
4 153.61 
5 136.09 
Non-oxidize Control 
136.74 
______________________________________ 
The above data demonstrates that the durable press results were equivalent 
to or exceeded the resin control and that the non-formaldehyde fabric was 
rendered white by the oxidative afterwash. Further, the whiteness of 
afterwashed fabrics decreased sharply at a peroxide level below 1% owb at 
160.degree.-180.degree. F. in the washers. 
As indicated above, the oxidative treatment in accordance with the present 
invention may be carried out by adding the oxidant to the non-formaldehyde 
finishing formula itself. That is, the treatment may be conducted 
simultaneously with a durable press finishing operation using, for 
example, glyoxal. An example of such simultaneous operation without the 
necessity for a separate afterwashing treatment is set forth below. 
EXAMPLE V 
The following finish formulations were evaluated to determine the effects 
of oxidizing agents in the finish bath on the yellowing of fabrics treated 
with glyoxal. In each example, Springs 65/35 polyester/cotton Style 638 
was padded with a wet pickup to apprxoimately 60 percent. The samples were 
dried after padding in the laboratory oven at 250.degree. F. for 30 
seconds, then cured in the oven at 400.degree. F. for 20 seconds. 
______________________________________ 
Chemicals (Grams/500 ml) 
Mix 1 Mix 2 Mix 3 
______________________________________ 
Glyoxal 15 15 15 
Aluminum sulfate/ 
13 13 13 
magnesium sulfate catalyst 
Anionic wetting agent 
1 1 1 
Polydimethyl siloxane 
5 5 5 
fluid emulsion 
Sodium perborate -- 0.1 0.5 
______________________________________ 
The above treated fabrics were then evaluated for improvement in whiteness 
by measuring their reflectance on a Macbeth MC1010 Spectrocolormeter. The 
whiteness index was calculated from the C.I.E. Tristimulus Values by the 
formula W.I.=4Z-3Y, using standard illuminant C. A high whiteness index 
indicated a good white appearance. 
The following whiteness indexes were achieved: 
______________________________________ 
Sample Whiteness Index 
______________________________________ 
1 138.56 
2 152.36 
3 154.20 
______________________________________ 
The following durable press and shrinkage values were obtained. 
______________________________________ 
DP Shrinkage (W,F) 
Sample 1W 5W 1W 5W 
______________________________________ 
1 3.25 3.25 .28,0 .83,0 
2 3.25 3.25 .28,0 .83,0 
3 3.25 3.25 .28,0 .83,0 
______________________________________ 
These results indicate that the inclusion of sodium perborate in finishing 
mixes 2 and 3 increased the whiteness significantly without diminishing 
the durable press or shrinkage properties. 
Another study was conducted to evaluate the effect of changes in 
concentration of sodium perborate at higher glyoxal levels on the 
whiteness index, durable press, and shrinkage. The following mixes were 
prepared and evaluated on Springs 65/35 polyester/cotton Style 393. In 
each sample a wet pickup of approximately 60 percent was achieved after 
padding with the finish mix. The samples were then dried and cured as 
before at 250.degree. F. for 30 seconds and 400.degree. F. for 20 seconds 
respectively. 
______________________________________ 
Chemicals 
(Grams/Liter) 
Mix 1 Mix 2 Mix 3 Mix 4 
______________________________________ 
Glyoxal 40 50 50 50 50 
Polydimethyl 10 10 10 10 
siloxane 
fluid emulsion 
Magnesium sulfate/ 
20 20 20 20 
aluminum sulfate 
catalyst 
Anionic wetting 
1 1 1 1 
agent 
Sodium perborate 
-- 0.05 0.1 0.2 
______________________________________ 
The following whiteness, durable press and shrinkage results were obtained. 
______________________________________ 
Whiteness 
DP Shrinkage (W,F) 
Sample Index 1W 5W 1W 5W 
______________________________________ 
1 127.6 4.0 3.5 .28,0 .83,0 
2 128.6 3.5 3.25 
.56,0 .94.0 
3 144.6 3.5 3.5 .56,0 .83,.28 
4 148.3 3.5 3.5 .28,0 .94.0 
______________________________________ 
The data indicate that by including sodium perborate in the finish bath, 
one is able to improve the whiteness of the finished fabric. There is a 
slight decrease in durable press and shrinkage performance, indicating 
that an optimal level for each chemical in the formulation should be 
determined. 
Another experiment was conducted to evaluate the use of alternative 
oxidizing agents in the finish bath. Obviously, the compounds evaluated 
are not inclusive and many other compounds, such as hydrogen peroxide and 
other peroxides, persulfates, percarbonates, potassium periodate, 
peroxyphosphates, perchlorates, organic per-acids, chlorites, 
hyporchlorites, etc. would be expected to improve the whiteness of the 
finished fabric. 
The following finish mixes were evaluated under the same padding, drying 
and curing conditions using Springs 65/35 polyester/cotton Style 411. 
______________________________________ 
Chemicals 
(Grams/Liter) 
Mix 1 Mix 2 Mix 3 Mix 4 
______________________________________ 
Glyoxal 40 120 120 120 120 
Aluminum sulfate/ 
40 40 40 40 
magnesium sulfate 
catalyst 
Polydimethyl 15 15 15 15 
siloxane fluid 
emulsion 
Sodium perborate 
-- 0.4 -- -- 
Sodium -- -- 0.4 -- 
percarbonate 
Peracetic acid* 
-- -- -- 15 
Anionic wetting 
1 1 1 1 
agent 
______________________________________ 
*Prepared by adding 2 parts of 50percent hydrogen peroxide to 1 part 
acetic anhydride. 
The fabric samples were evaluated as before for whiteness, durable press, 
and shrinkage properties. 
______________________________________ 
Whiteness DP Shrinkage (W,F) 
Sample 
Index 1W 5W 1W 5W 
______________________________________ 
1 108.4 4.0 4.0 .56,.28 
.56,.28 
2 117.3 3.5 3.5 .28,.28 
.56,.28 
3 120.1 4.0 3.5 .56,.28 
.94,.28 
4 119.7 4.0 3.5 .56,.28 
.83.,28 
______________________________________ 
The data demonstrate that these alternative oxidants will also improve the 
whiteness ratings of the treated fabrics with only minimal lowering of the 
durable press and shrinkage performance. 
EXAMPLE VI 
To determine the effect of afterwashing fabric treated with other glyoxal 
based resins which also impart fabric yellowing, the following trials were 
conducted on production equipment. 
The processing parameters were as follows: 
Range Speed: 125 yards/minute 
Range Temperature: 385.degree.-395.degree.-395.degree. F. 
The fabric was preblued with the following formula based on 250-gallon mix: 
______________________________________ 
Violet 3B 28 oz. 
Red B 3 oz. 
BRW Brightener 210 oz. 
______________________________________ 
The finish mixes were padded on in the conventional manner followed by 
passing the fabric over a vacuum slot having a vacuum of 12 in. Hg. 
______________________________________ 
Chemical Percent OWB 
______________________________________ 
FINISH MIX 1 
BASF Resin NFU 15.0% 
Catalyst 135-B 3.8% 
Softener CD 3.9% 
Springswet 300 0.1% 
FINISH MIX 2 
Permafresh ZF-3 15% 
Catalyst 135-B 3.8% 
Softener CD 3.0% 
Springset 300 0.1% 
______________________________________ 
The wet pickup achieved after vacuuming was approximately 27 percent. 
The fabric then was oxidatively afterwashed by passing through four wash 
boxes at 160.degree. F. containing the following formulation on the weight 
of the bath: 
______________________________________ 
Sodium perborate 2% 
Hydrogen peroxide (50%) 
1% 
Soda ash 0.5% 
Springs Stabilizer 100 
0.5% 
______________________________________ 
The fabric was then top softened followed by drying on cans. The top 
softening formulation consisted of the following formula based on the 
weight of the bath: 
______________________________________ 
Softener 1442 4.0% 
Acetic acid (50%) 
0.2% 
Springswet 300 0.05% 
______________________________________ 
Both of these finish formulations have been observed in the laboratory to 
exhibit yellowing. 
The following values were achieved on the above production trials: 
______________________________________ 
Durable Press 
Shrinkage (W,F) 
Mix Whiteness Index 
1W 5W 1W 5W 
______________________________________ 
1 188 3.2 3.1 1.39,0 
1.67,0 
2 189 3.2 3.1 1.50,0 
2.22,0 
______________________________________ 
This study indicates that good whiteness may be achieved on fabrics treated 
with glyoxal-based resins followed by oxidative afterwashing. 
EXAMPLE VII 
To demonstrate the improvement in shade stability during storage achievable 
through oxidative afterwashing, the following glyoxal finish bath was 
prepared: 
______________________________________ 
Chemical Grams/5 Gallons 
Percent 
______________________________________ 
Glyoxal 40 LF 2760 12.0 
Polydimethyl siloxane 
345 1.5 
fluid emulsion 
Aluminum sulfate/ 
920 4.0 
magnesium sulfate catalyst 
Springswet 300 23 0.1 
______________________________________ 
The mix was padded on preblued Springs 65/35 polyester/cotton Sytle 411 
with a wet pickup of approximately 50 to 60 percent. The fabric was dried 
on the tenter frame at 250.degree. F. for one minute, then cured in the 
tenter frame at 400.degree. F. for 20 seconds. 
Part of the fabric was then given an oxidative afterwash in the dye jig at 
160.degree.-180.degree. F. using the following formula: 
______________________________________ 
Chemical Grams/5 Gallons 
Percent 
______________________________________ 
Hydrogen peroxide 
6900 3.0 
(50 percent) 
Caustic (50 percent) 
2300 1.0 
Sodium silicate 
2300 1.0 
______________________________________ 
The fabric was then rinsed, neutralized with acetic acid, following by a 
final rinse. The fabric was finally dried on the tenter frame at 
250.degree. F. for one minute. 
An initial whiteness index was determined, and then the samples were stored 
in the dark in a laboratory desk drawer. The samples were remeasured after 
two years again for their whiteness indexes. The following results were 
obtained: 
______________________________________ 
Whiteness Index 
Sample September 1982 
September 1984 
______________________________________ 
Glyoxal finished 
146.7 104.8 
Glyoxal finished plus 
166.1 166.1 
oxidative afterwash 
______________________________________ 
The above test indicates that the oxidative afterwash treatment of glyoxal 
finish fabric will stabilize the white shade and prevent yellowing during 
storage. 
Part of the fabric was then oxidatively afterwashing at 160.degree. F. in a 
solution consisting of the following for approximately 30 seconds, 
followed by souring in a dilute acetic acid solution and final water 
rinsing. 
______________________________________ 
Chemical Grams per 2 Liters 
______________________________________ 
Hydrogen peroxide (50%) 
60 
Caustic (50%) 20 
Sodium Silicate 20 
Springscour 155 2 
______________________________________ 
Fabric samples from both the original and oxidatively afterwashed were then 
aged in a humid oven at 240.degree. F. for 5.5 hours and were again 
evaluated for whiteness, durable press, and shrinkage. 
The following results were obtained: 
______________________________________ 
Whiteness 
Durable Press 
Shrinkage (W,F) 
Fabric Sample 
Index 1W 5W 1W 5W 
______________________________________ 
Glyoxal Finished 
144.6 3.5 3.5 .28,.28 
.83,.28 
Glyoxal Finished/ 
170.8 3.5 3.5 0,.28 .56,0 
Afterwashed 
Aged Glyoxal 
56.9 3.5 3.5 .28,.28 
.56,0 
Finished 
Aged Glyoxal 
124.5 3.5 3.5 0,.28 .28,0 
Finished/ 
Afterwashed 
______________________________________ 
These results indicate that upon accelerated aging, the oxidative afterwash 
will significantly reduce fabric yellowing of Glyoxal finished fabric. 
While the invention herein is described in what is presently believed to be 
a practical preferred embodiment thereof, it will be apparent many 
modifications may be made within the scope of the invention, which scope 
is to be accorded the broadest interpretation of the appended claims so as 
to encompass all equivalent methods and fabrics.