Polyamide dyeing process utilizing controlled anionic dye addition

A process for the dyeing of a fibrous article containing fibers of a polyamide polymer with an anionic dye and dyed products made by the process. The process includes immersing the article in a dyeing bath of a liquid solvent for the anionic dye. The liquid solvent and the article are heated to a temperature at least equal to the dyeing transition temperature of the fiber of polyamide polymer. The anionic dye is added to the dyeing bath as a miscible liquid concentrate at a dye addition rate during a controlled dye addition period. At least a portion of the dye is added while the solvent and the article are at a temperature at least equal to the dyeing transition temperature. Stirring of the bath during the dye addition period and while the solvent and article are at a temperature at least equal to the dyeing transition temperature is done to mix the dye concentrate with the solvent in the bath to form a dilute dye solution and to provide a flow of the dilute dye solution relative to the article to cause the dye to be transported to the article. The stirring also provides, on the average, essentially uniform dye transport of the anionic dye to the article. The dye addition rate is adjusted at least while the solvent and article are at a temperature at least equal to the dyeing transition temperature so that the dye addition rate is the primary control over the rate of dye uptake by the article.

BACKGROUND OF THE INVENTION 
The present invention relates to the dyeing of fibrous articles containing 
polyamide fibers with anionic dyes. 
Anionic dyes such as acid dyes and pre-metallized dyes are widely used for 
the dyeing of polyamide fibers in which the nitrogen-containing groups of 
the polyamide polymer serve as dye sites. In conventional dyeing processes 
using such dyes, articles containing the polyamide fibers are immersed in 
an aqueous bath containing a solution of the dye after any pre-treatment 
processes such as scouring. While a wide variety of dyeing equipment is 
used, it is typical for all of the dye to be used in the process to be 
present in the bath initially. The bath containing the dye and the article 
to be dyed is also usually at a very low initial temperature, e.g., 
80.degree.-120.degree. F. (26.7.degree.-48.9.degree. C.) increased 
gradually to an elevated temperature often as high as the boiling point as 
the dyeing progresses. 
While high quality dyeing can be achieved using the conventional dyeing 
process for some acid dyes such as small molecule "levelling" dyes, dye 
cycles to achieve levelling with such anionic dyes are sometimes extremely 
long and are therefore costly. Moreover, with large molecule acid and 
pre-metallized dyes which are desirable for applications requiring good 
light and/or wash fastness, there are often severe dye uniformity problems 
associated with the conventional dyeing process. 
Large molecule acid and pre-metallized dyes are often referred to as 
"structure sensitive" dyes since non-uniform dyeing can result from even 
minor, and otherwise undetected, variations in the fiber physical 
structure. While dye-levelling and/or retarding agents can be added to the 
dye bath to improve dyeing uniformity, such agents sometimes provide only 
limited increases in dye uniformity and usually have disadvantages 
including increased initial expense and higher cost to treat the spent 
dyeing bath. In addition, because of their retarding effect, such chemical 
agents can sometimes increase dyeing cycles or make it difficult to obtain 
deep colors or dark shades. Also, dye yields from anionic dyes, i.e., the 
strength of color produced from a given quantity of dye on the fiber, are 
sometimes not as high as desired. 
SUMMARY OF THE INVENTION 
The invention provides an improved process for the dyeing of a fibrous 
article containing fibers of a polyamide polymer with at least one anionic 
dye and dyed products made by the process. A process in accordance with 
the invention includes immersing the article in a dyeing bath of a liquid 
solvent for the anionic dye. The liquid solvent and the article are heated 
to a temperature at least equal to the dyeing transition temperature of 
the fiber of polyamide polymer. The anionic dye is added to the dyeing 
bath as a miscible liquid concentrate at a controlled dye addition rate 
during a dye addition period. At least a portion of the dye is added while 
the bath and article are at temperature at least equal to the dyeing 
transition temperature. Stirring of the bath during the dye addition 
period and while the solvent and article are up to the dyeing transition 
temperature is done to mix the dye concentrate with the solvent in the 
bath to form a dilute dye solution and to provide a flow of the dilute dye 
solution relative to the article to cause the dye to be transported to the 
article. The stirring also provides, on the average, essentially uniform 
dye transport of the anionic dye to the article. In accordance with the 
process, the dye rate is adjusted at least while the solvent and article 
are at a temperature at least equal to the dyeing transition temperature 
so that the dye addition rate is the primary control over the rate of dye 
uptake by the article. 
In accordance with a preferred form of the invention, the conditions in the 
liquid solvent are maintained so that the anionic dye transfers less than 
about 10%. 
In accordance with another preferred form of the invention, the process is 
performed in a dyeing machine in which the stirring provides a number of 
repetitive machine cycles and the dye addition rate is adjusted so that an 
amount of dye between about 0.5% and about 7% of the total dye is added to 
the dyeing bath during a machine cycle, most preferably between about 0.5% 
and about 3%. 
In accordance with another preferred form of the invention, stirring is 
performed generally constantly and at a constant rate in the bath at least 
while the solvent and the article are at a temperature at least equal to 
the dyeing transition temperature. 
In accordance with another preferred form of the invention, the dye is 
added continuously and at a constant rate during the dye addition period. 
In accordance with another preferred form of the invention, at least about 
33% of the dye is added to the bath while said solvent and said article 
are at a temperature at least equal to the dyeing transition temperature, 
most preferably at least about 50% of the dye is added at this time. 
In accordance with another preferred form of the invention, the dye 
addition rate is adjusted so that the concentration of dye at location of 
lowest concentration in the bath is not greater than about 100 times, most 
preferably not greater than 50 times, the final equilibrium concentration 
for any substantial period of time while the solvent and the article are 
at a temperature at least equal to the dyeing transition temperature. 
In accordance with another preferred form of the invention, the rate of dye 
addition is adjusted so that the concentration of dye in the solvent as 
measured at the point of lowest concentration in the bath is at least 
about 2.5 times, preferably at least about 3.5 times, the final 
equilibrium concentration for a sustained period of time while the solvent 
and the article are at a temperature at least equal to the dyeing 
transition temperature. Preferably, the sustained period of time comprises 
at least about 10% of the time when the solvent and the article are at a 
temperature at least equal to the dyeing transition temperature. 
In accordance with a preferred embodiment of the invention, the liquid dye 
concentrate is added into the solvent ahead of a circulation pump to form 
the dilute dye solution. Preferably, the liquid dye concentrate is added 
to the solvent using a metering pump. 
In accordance with another preferred form of the invention, the process 
further includes the step of hydrosetting before dyeing. 
In accordance with a preferred product in accordance with the invention, a 
dyed fabric is provided which comprises yarns containing fibers of a 
polyamide polymer. The dyed fabric contains at least one anionic dye with 
the dye being distributed in the fabric such that: 
the fibers are asymmetrically ring-dyed; and 
the fibers adjacent to the yarn outside surfaces contain more dye than 
fibers in the yarn interiors. 
In a preferred form of the dyed fabric in accordance with the invention, 
fibers adjacent to at least one of the front and back fabric surfaces of 
the fabric contain more dye than in the fabric interior 
In accordance with a preferred form of the fabric of the invention, the 
fabric is selected from the class consisting of knitted and woven fabrics, 
most preferably wherein the fibers are continuous filaments. 
The invention is useful in a wide variety of polyamide dyeing processes 
using anionic dyes and is particularly advantageous when employed to dye 
articles such as warp knit and woven fabrics in jet dyeing apparatus. In 
addition, the invention also is particularly useful for the dyeing of 
carpets in beck dyers. Surprisingly, it has been found that when used 
under conditions such that the dyes transfer less than 10%, anionic dyes 
are utilized more effectively which provides either better dye yields or 
the achievement of deep colors or dark shades which were otherwise 
difficult to obtain or were unobtainable. Also, dye cycles for all types 
of dyes can be substantially shortened. With structure sensitive anionic 
dyes, better uniformity is easily achieved even when two or more dyes are 
used which have differing rates of dye uptake. Moreover, the improvements 
in dyeing are often achievable without the use of or by using lower 
concentrations of chemical levelling or other chemical agents which, in 
significant concentrations, can complicate treatment of spent dyeing bath 
liquids.

DETAILED DESCRIPTION 
The process of the invention is useful for dyeing articles containing 
fibers of a variety of polyamides. The invention is particularly useful 
for fibers made from aliphatic polyamide homopolymers and copolymers which 
are melt-spinnable to form fibers which are amenable to processing for 
textile uses. A preferred class of such polyamides contains at least one 
of poly(hexamethylene adipamide) or poly(.epsilon.-caproamide) polymer 
units in an amount greater than about 60% by weight. A most preferred 
class of polyamides contains at least about 85% by weight 
poly(hexamethylene adipamide). In the examples which follow, homopolymer 
poly(hexamethylene adipamide) is referred to as 66 nylon. 
There are a wide variety of fibrous articles containing polyamide fibers 
which can be dyed using the process of the invention including, for 
example, yarns, fabric, carpets and garments. Fabrics include the usual 
textile forms including woven, knitted, and nonwoven varieties. The 
polyamide fiber in such articles can be present in a wide variety of forms 
including flat or textured continuous filaments, staple yarns, bulked 
continuous filaments, etc. The polyamide fiber can be present in the 
article together with any of a variety of other synthetic or natural 
fibers. Typical of such articles are staple yarns made from a "blend" of 
polyamide staple with other fibers and fabrics and garments made from such 
yarns. The invention is particularly useful with fabrics containing 
continuous filament polyamide yarns together with elastic fibers such as 
spandex sold under the trademark Lycra.RTM. by E. I. du Pont de Nemours & 
Company. The other fibers in such articles may or may not undergo dyeing 
as the polyamide fibers are dyed in the process. In addition, the 
polyamide fibers to be dyed may already contain the same or a different 
dye. For example, the process of the invention may be used for a dye "add" 
to get to "shade" with the fiber already containing most of the dye before 
the process is used. 
The dyes used in the practice of the present invention are anionic dyes and 
dyeing of the polyamide fiber is accomplished by uptake of the dyes 
through the association of the dye molecules with nitrogen-containing 
groups on the polyamide polymer molecules. Most anionic dyes are members 
of the well-known class of "acid" dyes. Another type of anionic dyes is 
the type referred to as "pre-metallized" dyes which are the reaction 
products of, for example, chromium or cobalt and selected dyes. As will 
become apparent hereinafter, mixtures of two or more dyes are often used 
to achieve a desired shade. In this application, the word "dye" may be 
used to refer to a single dye or multiple dyes as in a mixture of dyes 
used in a dyeing process or on a dyed article. In processes using more 
than one dye such as in dye mixtures to achieve compound shades, a process 
is intended to be within the scope of the invention provided that at least 
one dye of compound shade is applied to an article in accordance with the 
invention. 
In accordance with a preferred process in accordance with the invention, 
conditions are used in the dye bath so that anionic dyes transfer less 
than about 10%. Transfer is a measure of the propensity of anionic dyes to 
migrate from one dye site to another after being absorbed by the fiber. 
Transfer under a given set of conditions can be measured in a mock dye 
bath as in the transfer test method described hereinafter. 
Providing transfer of less than 10% can easily be accomplished by use of 
dyes from a preferred class of dyes, the "structure sensitive" anionic 
dyes. These dyes are usually large molecule acid ("milling") dyes or 
pre-metallized dyes which are non-levelling, i.e., the dye molecules do 
not "transfer" significantly and thus migrate very little from one dye 
site to another after being absorbed by the fiber. Typically, structure 
sensitive dyes "transfer" less than 10% under normal conditions of use. 
"Structure sensitive" is the term applied to such dyes since non-uniform 
dyeing can result from even minor, and otherwise undetected, variations in 
the fiber physical structure. Such variations arise from the cumulative 
effects of thermal, mechanical, and chemical energy inputs during fiber 
manufacturing (including finish application) and in subsequent textile 
processing. Despite their known difficulties in use, structure sensitive 
dyes are desirable for many applications due to their washfastness, 
lightfastness, or both. 
Without intending to limit this preferred form of the invention to these 
specific dyes, commonly used structure-sensitive dyes are represented, for 
example, by the list provided below (C.I. refers to the Color Index, 3rd 
edition, 1971): 
Highly Structure Sensitive 
C.I. Acid Green 28 
C.I. Acid Blue 290 
C.I. Acid Blue 264 
C.I. Acid Violet 54 
Nylanthrene Blue GLF.sup.1 
FNT .sup.1 Crompton & Knowles Corp., Charlotte, N.C. 28233 
Tectilon Fast Blue RW.sup.2 
FNT .sup.2 Ciba-Geigy Corp., Dyestuffs & Chemicals Div., Greensboro, N.C. 
27419-8300 
C.I. Acid Violet 103 
C.I. Acid Violet 48 
C.I Acid Blue 122 
C.I. Acid Blue 280 
C.I Acid Red 182 
C.I. Acid Brown 45 
Moderately Structure Sensitive 
C.I. Acid Orange 116 
C.I. Acid Blue 230 
C.I. Acid Red 114 
Structure sensitive (rate sensitive) dyes are discussed in more detail in 
Textile Chemist and Colorist, Vol. 17, No. 12, p.231 (1985). 
For dyes which are normally described as "levelling" dyes since they 
transfer readily and "level" under the normal conditions of use, transfer 
of less than about 10% can be accomplished using conditions of low pH, low 
temperature, or both. In addition, with dyes which are normally strongly 
levelling, it may be necessary to perform the dyeing rapidly even though 
the conditions in the dyeing bath are such that the dye transfers less 
than about 10%. Otherwise, the dye yield benefits which are otherwise 
obtainable using the invention may be diminished due to dye transfer which 
occurs after the dye is on the article. 
As in conventional dyeing processes, it is desirable to scour the article 
before dyeing to remove yarn finishes, sizing and other materials which 
may adversely affect the dyeing. In the use of the invention for dyeing 
warp knit fabrics, particularly for critical dye applications, it is 
important for the fabrics to be effectively scoured before dyeing. The 
fabrics can be scoured, for example, in an open width scouring range or in 
the apparatus to be used for the dyeing, e.g., a jet or beam dyer. 
Scouring solutions used conventionally are generally suitable, e.g., water 
at 180.degree. F. (82.2.degree. C.) containing a surfactant such as 0.5 
gram/liter of MERPOL LFH.RTM. (a liquid non-ionic detergent sold by E. I. 
Du Pont de Nemours & Company, Inc. of Wilmington, Del.). After scouring, 
the fabric should be rinsed such as by being immersed in hot water. 
As is done for known dyeing processes, it is desirable to heat-set some 
warp knit fabrics such as tricot before dyeing to stabilize the fabric and 
prevent "edge curling" which can cause unlevel dyeing. It is particularly 
desirable to heat-set elastic tricot fabrics since these fabric have a 
strong propensity to edge curl. It may be advantageous to dry and heat-set 
scoured fabrics in a single step such as in a pin tenter. Trimming the 
edges of the fabric during heat-setting may also assist in minimizing edge 
curling during dyeing. 
Another particularly advantageous technique for some fabrics such as warp 
knit fabrics for automotive uses is to hydroset the fabrics as part of the 
dyeing process. "Hydrosetting" is intended to refer to heating the fabric 
to a temperature sufficient to reduce yarn to yarn structure differences 
and "set" the yarns in the fabric while the fabric is in contact with 
liquid water. Usually, the water should be free of substantial quantities 
of chemicals or impurities. Hydrosetting can eliminate the heat-setting 
step and provide further increases in dye uniformity over the increased 
uniformity otherwise provided by the dyeing process of the invention. 
While hydrosetting can be done in an autoclave, hydrosetting can easily be 
accomplished in a process in accordance with the invention by hydrosetting 
in the dyeing bath but before any dye or other chemicals are added. This 
is a particularly useful technique when the dyeing is to be done in a jet 
dyer since most jet dyers have the capability to be pressurized to achieve 
the preferred temperatures. For 66 nylon, the bath is heated to a 
temperature of at least about 190.degree. F. (87.8.degree. C.), preferably 
between about 220.degree. F. (104.4.degree. C.) and about 270.degree. F. 
(132.2.degree. C.) for a time period between about 1 and 5 minutes. 
Usually, temperatures required for 6 nylon and 66 nylon copolymers are 
lower. Hydrosetting is referred to, for example, in U.S. Pat. No. 
4,731,485 at column 11, lines 43-47. 
In the process of the invention, the article to be dyed is immersed in a 
dyeing bath containing a liquid solvent for the anionic dye. The dyeing 
bath can take a wide variety of forms in which the article is totally 
immersed in the bath throughout the dyeing process or is partially 
immersed at any one time and is moved in a cyclical or random fashion to 
provide contact for the entire article with the solvent. Partial immersion 
is useful for articles such as fabrics where the fabric can be 
progressively advanced through the bath, either in continuous rope form or 
by reciprocation of an article having a discrete length, so that the 
entire article is ultimately dyed. 
A preferred process employs the bath formed in a jet-dyeing apparatus for 
fabric in which the fabric is in the form of an endless rope and is moved 
by means of a jet nozzle supplied with solvent pumped from the bath. 
Machines of this type include a jet-dyeing machine (Gaston County Dyeing 
Machine Company), a circular jet-dyeing machine (Hisaka Works, Ltd.), 
"Uni-Ace" dyeing machine (Nippon Dyeing Machine Company), HT dyeing 
machine "Loco-Overflow" (Hokuriku Chemical Machinery Co. Ltd.), "Masflow" 
installation (Masuda Manufacturing Co., Ltd.), and the like. 
When the fabric is loaded into a jet dyer for the practice of the preferred 
form of the invention and sewn at its ends to form the rope, it is 
preferable to use a straight, unbiased seam to minimize the chances of 
nonuniformity due to bias seaming. In larger scale processes, it has been 
found that tacking of the fabric rope into a tube is usually not desirable 
since tacking can impede access of the dye to the fabric. The jet dyer 
should be set up with a suitable jet nozzle to allow for complete 
reorientation of the fabric during dyeing and a suitable turnover rate 
should be provided as will become more apparent hereinafter. It is also 
usually desirable to avoid overcrowding in the kier and thus the amount of 
fabric to be dyed should be limited appropriately. 
The liquid solvent for the dye is any suitable solvent for the dye which is 
capable of transporting the dye to the dye sites on the fiber and which is 
otherwise compatible with the fabric, dye and other aspects of the 
process, e.g., aqueous liquids and methanol are suitable solvents. 
Preferably, the liquid solvent is an aqueous liquid which contains less 
than about 10% by weight of additives for establishing and maintaining the 
desired pH and for other purposes Suitable aqueous liquids useful in the 
process contain additives for providing a buffer system. For example, 
acetic acid on the order of about 1% and ammonium acetate on the order of 
about 2% by weight can be used to adjust the pH to a suitable level. Other 
additives can be chemicals such as levelling agents, retarders, and the 
like which are referred to collectively in the present application as 
"dyeing auxiliaries". Dyeing auxiliaries can be present in the process of 
the invention although such agents often are not needed. If dyeing 
auxiliaries are present in the bath, a much lower concentration is 
typically used to keep the dye cycle to a reasonably short duration. 
Dyeing auxiliaries can be useful and may be desirable for compound shades 
of dyes of differing affinities. 
When the bath has low levels of or is substantially free of dyeing 
auxiliaries, significant advantages are obtained in the treatment or 
disposal of the spent dye liquors. Moreover, the dyed fiber may be 
substantially free of residual dyeing auxiliaries or such agents may be 
present only at much lower levels than in fibers dyed by the conventional 
process for structure sensitive dyes which typically require high bath 
concentrations of dyeing auxiliaries. In addition, it is possible in some 
instances to use the spent dyeing bath for after-treatments such as for 
improving wetfastness, lightfastness or softness, applying antistats, and 
for other known after-treatments employing chemical agents. For such after 
treatments, the chemical agent can be added to the hot bath using a 
technique similar to that used to add the dye in a process in accordance 
with the invention. In addition, it is also possible to reuse the spent 
bath in a subsequent dyeing if dyeing auxiliaries are absent or are 
present in sufficiently low concentration. 
The anionic dye is added to the dyeing bath ad a miscible liquid 
concentrate at a controlled dye addition rate during a dye addition 
period. "Dye addition period" refers to the time period beginning with the 
first addition of dye and ending with the final amount of dye being added. 
The length of the dye addition period will usually range between about 5 
minutes and about 4 hours with typical dye addition periods being between 
about 20 and about 100 minutes. Upon stirring as will be explained in more 
detail, the miscible liquid dye concentrate is mixed with the solvent in 
the bath to form a dilute dye solution. "Miscible liquid concentrate" is 
intended to refer to a solution in which the dye is fully dissolved and 
which can be added to and mixed with the liquid solvent in the bath to 
form a dilute liquid solution of the dye in all proportions of such 
concentrates which would normally be mixed into a dye bath. The solvent 
for the miscible liquid concentrate can be different than the liquid 
solvent provided that the introduction of a different solvent does not 
otherwise adversely affect the dyeing process. When an aqueous dyeing bath 
is used, the solvent preferably used in the miscible liquid concentrate is 
water. 
As will be explained in more detail hereinafter, the dye addition rate is 
adjusted depending on the amount of dye to be applied, the characteristics 
of the article to be dyed, the type of dyeing apparatus, the type of dye 
and the conditions of the dyeing to achieve the desired results. 
Preferably, to facilitate control over the process and make the process 
more easily reproducible, the dye is added continuously and at a constant 
rate during the dye addition period. 
In processes in which the dilute dye solution in the bath is circulated by 
means of a circulation pump, the liquid dye concentrate is preferably 
added to the solvent ahead of the circulation pump. A metering pump is 
advantageously utilized for this purpose. Preferably, when dyeing fabric 
in a jet dyer, the circulation pump supplies the dilute dye solution to 
the jet nozzle so that the newly-added dye contacts the fabric first in 
the jet. 
In a process in accordance with the invention, the dye bath containing the 
solvent and the article in the dyeing bath are heated to a temperature at 
least equal to the dyeing transition temperature. For the purposes of this 
application, dyeing transition temperature refers to the temperature 
during dyeing with a particular dye at which the fiber structure opens up 
sufficiently to allow a marked increase in the rate of dye uptake. The 
dyeing transition temperature for a dye/fiber combination may be 
determined by running a dyeing under the condition to be used and plotting 
% dye exhaust with respect to dye bath temperature when increased at 
3.degree. C./min. The temperature at 15% exhaust is the dyeing transition 
temperature. If more than one dye is to be used in a dyeing process, the 
temperature in the dyeing process is preferably at least equal to the 
dyeing transition temperature of the dye having the highest dyeing 
transition temperature (usually also the most structure sensitive). In the 
preferred form of the invention using jet dyeing apparatus, heating can be 
achieved using a heat exchanger through which liquid from the bath is 
circulated externally. 
In a process in accordance with the invention, at least a portion of the 
dye is added while the solvent and the article are at a temperature at 
least equal to the dyeing transition temperature. This part of the dyeing 
process can be referred to as the "rapid dye uptake phase", i.e., the time 
period where there is dye in the bath and the solvent and article are at a 
temperature at least equal to the dyeing transition temperature. In a 
process where no dye is added to the bath until the solvent and article 
are at least equal to the dyeing transition temperature, the rapid dye 
uptake phase will begin when dye is first added to the bath. In a process 
where dye addition is begun before the bath is up to temperature, the 
rapid dye uptake phase will begin when the solvent and article reach a 
temperature at least equal to the dyeing transition temperature. In 
typical processes, the rapid dye uptake phase will end when the bath is 
exhausted toward or at the end of the dyeing process. 
During the rapid dye uptake phase in one preferred process in accordance 
with the invention, the temperature of the bath and the article in the 
bath is maintained generally constant so that the dyeing process is not 
affected by temperature changes which may affect the rate of dye uptake by 
the article. Generally, provided that the temperature remains above the 
dyeing transition temperature, the temperature should be controlled to 
within .+-.10.degree. C., preferably .+-.5.degree. C. Also, in aqueous 
systems, it is usually preferable for the pH to be maintained generally 
constant. It has been found that controlling the pH to within about 
.+-.0.2 units is suitable. 
In some processes, particularly processes using a dye mixture where one dye 
is structure sensitive and the other is strongly levelling, it may be 
desirable to decrease the pH and/or lower the temperature as the dyeing 
progresses to promote the exhaustion of the levelling dye from the bath. 
This is usually desirable towards or at the end of the dyeing since the 
structure sensitive dye may strike too fast and cause an unlevel dyeing if 
the pH or temperature is too low initially. Decreasing the pH can be done 
by metering a suitable acid solution such as acetic acid into the bath 
after the dye addition period or by using an acid donor such as the acid 
donor sold by Sandoz Chemical Co. under the trademark SANDACID V.RTM. 
which hydrolyzes and lowers pH in a gradual, controlled manner. 
In a preferred process of the invention, at least about 33% of the dye is 
added to the bath when the solvent and the article are at least equal to 
the dyeing transition temperature, i.e., during the rapid dye uptake 
phase. Most preferably, at least about 50% of the dye is added during the 
rapid dye uptake phase. As will become more apparent in the examples which 
follow, increasing dye yield benefits will be obtained with increases in 
the amount of dye added during the rapid dye uptake phase. However, it may 
be desirable to forgo some of the dye yield increase to take advantage of 
decreased cycle time which may be obtained by adding at least some of the 
dye into the bath before it is up to the dyeing transition temperature. 
Stirring of the bath during the dye addition period and the rapid dye 
uptake phase is done to mix the dye concentrate with the solvent in the 
bath to form a dilute dye solution and to provide a flow of the dilute dye 
solution relative to the article to cause the dye to be transported to the 
article. The term "stirring" is intended to include any means of mixing 
and imparting relative motion between the article and the solvent in the 
dyeing bath. The relative motion between the article and the solvent can 
be imparted by circulating the solvent in the dye bath, moving the article 
in the solvent, or both moving the article and circulating the liquid. In 
the preferred process employing a jet-dyeing apparatus, both the article 
is moved and the bath liquid is circulated by action of circulating liquid 
with the fabric circulation being usually assisted by a rotating reel 
usually provided in such equipment. 
The stirring also provides, on the average, essentially uniform dye 
transport of the anionic dye to the article during the dye addition period 
and rapid dye uptake phase so that a dyeing results which is sufficiently 
visually level to be useful for the intended purpose. Typically, a 
visually level fabric has shade variations across the fabric which are 
less than about 5%. Thus, during a process in which there are a number of 
repetitive cycles as in the preferred form of the invention in a jet dyer 
where the fabric rope cycles numerous times through the jet nozzle, the 
dye transport to the fabric may not be uniform in any one machine cycle. 
However, the additive effect of dye transport during all of the cycles is 
such that a level dyeing results since dye transport "on the average" is 
essentially uniform. As will become more apparent hereinafter, it may be 
desirable to increase the turnover rate, limit the dye addition rate, or 
both to decrease the percentage of total dye added per cycle and thereby 
increase uniformity due to the greater averaging effect obtained. To 
facilitate control over the process and to enable a process to be 
repeated, it is preferable for stirring to be performed constantly and at 
a constant rate. 
In accordance with the invention, the dye addition rate is adjusted to be 
the primary control over the rate of dye uptake by the article at least 
while the solvent and the article are at or above the dyeing transition 
temperature. The type of adjustment of the dye addition rate necessary to 
accomplish this may be better understood by reference to Equation I which 
takes into account factors impacting the dyeing process: 
##EQU1## 
In Equation I, Ds is the diffusion coefficient of the dye in solution, Df 
is the diffusion coefficient of the dye in the fiber, K is the equilibrium 
distribution coefficient for the dye-fiber system, r is the radius of the 
fiber, and .delta. is thickness of the diffusional boundary layer. In a 
process in accordance with the invention, it has been discovered that 
adjusting the rate of dye addition into the bath and coordinating the rate 
with other conditions in the bath so that the rate of dye addition is the 
primary control over the rate of dye uptake provides low values for L in 
Equation I. It has further been discovered that the maximum benefits of 
the invention result when L is very low, preferably approaching zero. 
To cause the rate of dye addition to be the primary control over the rate 
of dye uptake and thereby provide low L values, the rate of dye addition 
is limited so that the fibrous article, which is readily capable of 
accepting dye since it is above the dyeing transition temperature, is 
capable of accepting more dye than is supplied to it. Under these 
conditions, the concentration of dye in the bath is very much lower than 
in a conventional process and the influence of the diffusion coefficient 
in the fiber, Df, is therefore substantially less significant than in a 
conventional process. Also, the value for Ds/(K.multidot.Df) will be 
smaller than in a conventional process and will lead to lower L values, 
primarily because the value for K will increase as the concentration of 
dye in the dye bath decreases. This effect is particularly pronounced in 
the preferred form of the invention where dyes are used and/or conditions 
established so that the dyes transfer less than about 10%. In such cases, 
the value for K is very high and is further increased by the limited 
concentration of dye in the bath. 
Preferably, the dye addition rate is adjusted so that the concentration of 
dye in the solvent at the location of lowest concentration in the dyer is 
not greater than about 100 times the final equilibrium concentration for 
any substantial period of time while the solvent and the article are at a 
temperature at least equal to the dyeing transition temperature. In a 
process in accordance with the invention in which the dye is added to the 
bath before the dyeing transition temperature is reached, a high 
concentration of dye may temporarily be present in the bath while the bath 
is at or above the dyeing transition temperature. This time period with 
high concentration should not be a substantial period of time, i.e., 
should not be greater than about 10% of the time when the bath is at or 
above the dyeing transition temperature. For the maximum benefits to be 
obtained when conditions are used or dyes are selected so that the dyes 
transfer less than about 10%, it is preferred for the concentration to not 
be greater than 100 times the final equilibrium concentration for any 
period of time while the bath is at or above the dyeing transition 
temperature. Most preferably, the dye addition rate is adjusted so that 
the concentration does not exceed about 50 times the final equilibrium 
concentration. 
The "final equilibrium concentration" is the concentration of dye in the 
dyebath for a particular % dye on the article under the process conditions 
at which there is essentially no further increase in the depth of dyeing 
without the addition of new dye. The final equilibrium concentration can 
be determined with reasonable certainty in the process itself by 
extrapolation from the concentration measured in the dye bath at the end 
of the dyeing process. Usually, when the dyeing process is complete in a 
commercial dyeing, the dye will have been sufficiently exhausted (and will 
have a uniform concentration in the bath) so that the final concentration 
before the bath is dropped can be assigned as the final equilibrium 
concentration. During the dyeing process, the location of lowest 
concentration in the dyer is usually just ahead of where dye is introduced 
into the bath. For example, in a process where the solvent is circulated 
using a pump and the dye is added ahead of the pump, the concentration of 
the dye in the solvent just ahead of where the dye is added will be the 
lowest concentration. In commercial jet dyers, existing sampling ports 
which are remote from the jet are also suitable for measuring this 
concentration since the sample obtained at such ports is essentially 
equivalent to the concentration just ahead of where dye is introduced into 
the bath. 
In contrast, in a conventional process for dyeing nylon, the dye in the 
bath is initially on the order of 300-500 or more times the equilibrium 
concentration and remains in this range for a significant time until it is 
gradually decreased as the temperature is slowly increased to cause the 
dyeing to progress. If concentrations were to equal the concentrations 
used in conventional dyeings for a substantial period of time while the 
fiber contained little dye and was well above the dyeing transition 
temperature, a visually un-level dyeing likely would result, particularly 
when conditions are used or dyes are selected so that the dyes transfer 
less than about 10%. 
To more fully realize the decrease in dye cycle times which are achievable 
in accordance with the present invention, the rate of dye addition is also 
preferably adjusted so that the concentration of dye in the solvent, as 
measured at the location of lowest concentration in the bath, is at least 
about 2.5 times the final equilibrium concentration for a sustained period 
of time while the solvent and the article are at a temperature at least 
equal to the dyeing transition temperature. Preferably, the sustained 
period of time comprises at least about 10% of the time while the solvent 
and the article are at a temperature at least equal to the dyeing 
transition temperature. Preferably, the concentration in the bath at the 
location of lowest concentration will be at least about 3.5 times the 
equilibrium concentration. 
In commercial processes employing a number of repetitive machine cycles, 
e.g., turnovers of the rope in a jet or beck dyer or circulation of the 
bath in a beam dyer, it is preferable to adjust the rate of dye addition 
so that an amount of dye between about 0.5% and about 7% of the total dye 
is added in a machine cycle to achieve, on the average, essentially 
uniform dye transport and a visually level dyeing in accordance with the 
invention. Most preferably, an amount of dye between about 0.5% and about 
3% is added during a machine cycle. Using laboratory jet and beck dyeing 
equipment, percentages of total dye per cycle are typically lower since 
laboratory equipment usually has a high turnover rate which would not be 
practical for use in large commercial dyeing equipment although excellent 
results are obtained. 
Rates of dye addition based on the fabric weight in commercial jet and beck 
dyers are usually on the order of about 0.0005 to 0.5% dye/minute. The 
rates at the lower end of the range are useful for low percent 
dye-on-fiber dyeings with extremely high affinity dyes to provide a 
sufficient number of machine cycles for adequate averaging to provide 
essentially uniform dye transport. 
Using the preferred process of the invention in which conditions are used 
so that the dyes transfer less than 10% in the same equipment used for 
conventional polyamide dyeings, articles containing dyed polyamide fiber 
can be produced with a higher relative dye strength for the same relative 
dye content, i.e., to have a higher relative dye yield, than can be 
obtained using conventional processes. Depending on the type of dye being 
used, the temperature and pH conditions in the dyebath can be used to 
adjust the relative dye yields obtained for a process of the invention in 
the same type of equipment under the same conditions. For example, with 
most anionic dyes, decreasing the pH will provide increases in relative 
dye yields. For dyes which level under conventional conditions, it may be 
desirable to employ lower temperatures which has the primary effect of 
decreasing transfer. With increased temperatures above the dye transition 
temperature, relative dye yields provided by many structure sensitive dyes 
may increase. However, in general, conditions which produce the maximum 
benefits in terms of dye yield with structure sensitive dyes may make it 
more difficult to obtain a visually level dyeing. Accordingly, it may be 
necessary to select conditions which provide a compromise between relative 
dye yield increases and still provide a level dyeing without extraordinary 
care. 
The preferred process of the invention using dyes under conditions such 
that the transfer is less than 10% is capable of minimizing the 
sensitivity to structural differences in the fibers which can lead to 
non-uniform dyeing. Provided that the transport of the dye to the article 
is, on the average, essentially uniform, a visually level dyeing will 
result which can cover streaks in a fabric due to structural differences 
in the yarns and produce dyed fabric with a higher uniformity rating than 
is produced using a conventional process. 
It is also possible to adjust the results of the invention by including 
dyeing auxiliaries in the solvent in the dye bath or including them in the 
dye concentrate. In general, auxiliaries which decrease the strike rate of 
the dye will decrease the relative dye yield obtained and the dyeing will 
be more like a conventional dyeing. In addition, where the dye is added 
into the bath before the bath has reached its dyeing transition 
temperature, the dye which is absorbed by the fiber before the dyeing 
transition temperature is reached will impart some conventional dyeing 
characteristics to the fiber in the article. 
For setting up a commercial process in a jet dyer in accordance with the 
invention, it is advantageous for the process to be run first in 
laboratory scale equipment corresponding generally to the chosen process 
conditions. In the laboratory scale process, a dye addition rate can 
thereby be determined in advance or a rate based on past experience for 
the same or similar dyeings can be confirmed. Due to smaller ratios of the 
weight of the bath to the weight of the goods and particularly the lower 
turnover rates in larger scale dyers compared to typical laboratory dyers, 
the dye addition rate or conditions used may have to be further modified 
for successful larger scale dyeings. 
In the preferred form of the invention, it is usually only necessary to 
carefully control the process during the rapid dye uptake phase and, at 
most other times during the process, temperature and other bath conditions 
need not be as carefully controlled. For example, elevating the bath to 
the desired temperature can be done quickly and pH adjustment prior to dye 
addition can be done expeditiously and without the degree of care required 
in the conventional process for dyeing nylon. This is particularly 
advantageous since, with only one critical stage and when constant 
temperature and pH are employed, the procedure will be easily reproducible 
and it will be possible to efficiently make repetitive dyeings of the same 
fabric. Moreover, in the event that it is discovered early in a dyeing 
process that the conditions in the bath are not as desired, the dye 
addition can be stopped and the desired conditions established before the 
dyeing is resumed. 
After the dyeing is complete, the dyeing bath is cooled, typically to below 
about 175.degree. F. (79.4.degree. C.) and dropped. The article can be 
rinsed, dried and subsequently used in a conventional manner. 
Referring now to FIG. 4 showing a cross-sectional photomicrograph at 400X 
of a preferred dyed fabric in accordance with the invention (Example 
8--Part B), it is seen that the yarn filaments adjacent to the outside 
surfaces of the 66 nylon continuous filament yarns contain more dye than 
filaments in the interior of the yarn. In the yarn shown in FIG. 4, the 
dye is concentrated sufficiently in the outer filaments that some of the 
interior filaments appear to have little or no dye. In addition, filaments 
are asymmetrically ring-dyed, i.e., the filaments are dyed with more dye 
being present adjacent to the surface of the filaments than in the 
interior but the ring-dying of at least some of the filaments is 
asymmetric, i.e., more dye being present on one side or the other. It will 
be understood that in continuous filament yarns, the same filaments may 
exhibit different dyeing effects along the length of the yarn since the 
filaments may be in different positions in the yarn bundle. 
FIG. 5 is a cross-sectional photomicrograph at the same magnification of a 
fabric dyed conventionally in the same apparatus (Example 8--Part A). It 
is apparent that the dye is distributed more evenly throughout the yarn 
bundle with little difference between surface and interior filaments. 
Little ring-dyeing has occurred and, to the extent that ring dyeing is 
visible, it appears to be symmetric. 
As shown in FIG. 6 which is the same fabric of FIG. 4 at 250X, fabrics in 
accordance with the invention also have more dye on yarns adjacent to the 
surfaces of the fabric than in the interior of the fabric. FIG. 7 shows a 
conventionally dyed fabric (same as FIG. 5 at 250X) in which the dye is 
distributed generally evenly throughout the fabric. 
Despite the asymmetric dyeing of the yarns and filaments, fabrics of the 
invention are visually level and are highly uniform. Moreover, the 
uniformity is often better than fabrics dyed conventionally, particularly 
with structure sensitive dyes. Often, streaks which appear in a fabric 
dyed conventionally due to non-uniformity in the yarn can be reduced or 
substantially eliminated in a dyed fabric in accordance with the 
invention. In the most preferred dyed fabrics in accordance with the 
invention, the fabrics are essentially free of end-to-end dye 
non-uniformities. In addition, the fabrics are equivalent to conventional 
fabrics in lightfastness, washfastness and in abrasion tests such as the 
Stoll abrasion test. 
Although the invention is applicable to other types of fabrics such as 
non-wovens and tufted fabrics used for carpeting, preferred fabrics in 
accordance with the invention are selected from the class consisting of 
knitted and woven fabrics, most preferably those made using continuous 
filament yarns since dyed fabrics of this type with high uniformity 
ratings are often difficult to achieve. In addition, the fabric of the 
invention preferably contains at least one structure sensitive anionic 
dye. 
The invention is applicable to other ionically-dyeable polyamides with 
other ionic dyes such as the dyeing of cationically-dyeable polyamides 
with cationic dyes. For example, polyamides modified with 
5-sulpho-isophthalate can be dyed with cationic dyes such as SEVRON Blue 
5GMF (C.I Basic Blue 3) using the process of the invention. 
TEST METHODS 
The Dye Transition Temperature is determined for a fiber/dye combination as 
follows: 
A sample of the article is prescoured in a bath containing 800 g water/g of 
sample with 0.5 g/l of tetrasodiumpyrophosphate and 0.5 g/l of MERPOL 
HCS.RTM. (a liquid non-ionic detergent sold by E. I. du Pont de Nemours & 
Company). The bath temperature is raised at a rate of about 3.degree. 
C./min. until the bath temperature is 60.degree. C. The temperature is 
held for 15 minutes at 60.degree. C., then the fiber is rinsed. (Note that 
the prescour temperature must not exceed the dye transition temperature of 
the fiber. If the dye transition temperature appears to be close to the 
prescour temperature, the procedure should be repeated at a lower prescour 
temperature.) The bath (without the article) with a similar quantity of 
water is adjusted to 30.degree. C. and 1% (based on the weight of the 
article) of the dye to be used and 5 g/l of monobasic sodium phosphate are 
added. (If more than one dye is to be used in the dyeing process, the dye 
believed to have the highest Dye Transition Temperature should be used to 
determine Dye Transition Temperature. Usually, this dye will also be the 
most structure sensitive.) The pH is adjusted to 5.0 using monobasic 
sodium phosphate and acetic acid. The article is added and the bath 
temperature is increased to 95.degree. C. at a rate of 3.degree. C./min. 
With every 5.degree. C. rise in bath temperature a dye liquor sample of 
.about.25 ml is taken from the dye bath. The samples are cooled to room 
temperature and the absorbance of each sample at a wavelength known to be 
useful for monitoring the dye is measured on a spectrophotometer such as a 
Perkin-Elmer C552-000 UV-visible spectrophotometer (Perkin-Elmer 
Instruments, Norwalk, Conn. 06856) using a water reference. The % dye 
exhaust is calculated and plotted with respect to dyebath temperature. The 
temperature at 15% exhaust is the dye transition temperature. 
% Transfer can be determined using the AATCC Test Method 159-1989 (AATCC 
Technical Manual/1991, p. 285-286) except with the mock dyebath being at 
the pH and temperature of the actual process under consideration and a 30 
minute time period is used. Percent transfer is calculated in this method 
by measuring the relative dye strength of the original dyed sample before 
(control, 100% relative dye strength) and after the transfer procedure. 
The difference is the % transfer. 
Relative Dye Strength is a relative measure of the strength of dye in a 
fabric determined photometrically for a series of fabrics dyed with the 
same dye with the sample dyed by the comparative or control procedure 
being arbitrarily designated as having 100% relative dye strength. 
Relative dye strength for a fabric sample is measured at the wavelength of 
minimum reflectance using a MACBETH COLOR EYE 1500 PLUS SYSTEM 
Spectrophotometer, sold by Macbeth Division of Kollmorgen Instrument Corp. 
of Newburg, N.Y. A scan from 750 to 350 nm can be performed to determine 
the wavelength of minimum reflectance for the dye. All subsequent samples 
in a series with the same dye are then measured at the same wavelength. 
For example, the wavelength of minimum reflectance for C.I. Acid Blue 122 
is 640 nm. 
The sample produced by the comparative or control procedure is designated 
the control and assigned a relative dye strength of 100%. The remaining 
samples are then scaled in relative dye strength by the following: 
##EQU2## 
where: R=reflectance. 
Relative Dye Content is a relative measure of dye content determined 
photometrically for a series of fabrics dyed with the same dye with the 
sample dyed by the comparative or control procedure being arbitrarily 
designated as having a 100% relative dye content. 
The relative dye content is determined in the following way. First, a 
sample of the article is cut into small segments and about 0.1 gram is 
weighed to .+-.0.1 mg accuracy. Typically, a test series of samples of 
dyed articles is weighed to each have very nearly the same weights. The 
samples are dissolved in 30 ml of formic acid at ambient temperature. 
After sample dissolution is complete, centrifugation for 20 minutes is 
effective for removing titanium dioxide delusterant when present. 
A Perkin-Elmer C552-000 UV-visible spectrophotometer (Perkin-Elmer 
Instruments, Norwalk, Conn. 06856) is used to record the absorbance of the 
samples. A scan from 750 to 350 nm is performed and the largest peaks are 
chosen as analytical wavelengths for the dye tested. All subsequent 
samples in a series with the same dye are then measured at these 
wavelengths. Typically, sample sizes around 0.1 gram give absorbance 
readings in the range of 0.3 AU to 0.8 AU for the dye levels obtained. 
A corrected absorbance is calculated for each wavelength measured on every 
sample in the series. The corrected absorbance is: 
EQU A (corrected)=(S.times.0.1 gram)/W 
where: S=absorbance at a given wavelength; and W=weight of sample in grams 
The sample dyed by the comparative or control procedure is assigned a 
relative dye content of 100%. The remaining samples are then scaled in 
relative dye content by the following: 
EQU Rel Dye Content (%)=(As'100)/A.sub.1 
where: A.sub.s =average absorbance of sample; and A.sub.1 =average 
absorbance of the control sample. 
This calculation is performed for every analytical wavelength chosen in a 
given dye series. 
Yarn Cross-sectional Micrographs 
Fabric swatches, or yarn bundles, are embedded in "Marglas", or a similar 
epoxy resin designed for microtomy. Approximately ten micron thick 
sections are made using a steel microtome knife. These sections are cut in 
a direction which will enable examining cross sections of fibers at 
various depths into the fabric. The sections are placed on a microscope 
slide and immersed in a refractive index liquid which matches, and 
therefore renders invisible, the epoxy embedding material. Magnifications 
of 100x to 500x, using objective lenses of 10x to 40x are convenient and 
useful for assessing distributions of dye within the filaments, within the 
yarn bundles and through the fabric thickness. 
Relative Dye Yield is defined as the ratio of the Relative Dye Strength to 
the Relative Dye Content: 
##EQU3## 
Dyebath Concentrations are measured using a Perkin-Elmer Lambda 2 
Spectrophotometer (Perkin-Elmer Instruments, Norwalk, Conn. 06856) using 
wavelengths with high absorbance for the dye or dyes being measured. 
Fabric Uniformity Ratings are determined by the following procedure: 
Fabric swatches are laid on a large table in a room with diffuse 
fluorescent lighting. The fabric is rated by a panel of experts on a scale 
from 1 to 10 using the computerized simulation of fabric streaks now being 
considered for a standard by the AATCC (Committee RA97, Assessment of 
Barre,). Copies of the computerized simulations are attached as FIGS. 
8-17. 
The invention is illustrated in the following examples which are not 
intended to be limiting. Percentages are by weight unless otherwise 
indicated. 
EXAMPLE 1 
50 grams of a warp knit fabric (10 in.times.72 in) from a 45 denier, 
trilobal 4.5 dpf 66 nylon fiber are sewn into a tube widthwise. The fabric 
is then introduced into a Werner-Mathis Laboratory Jet Dyeing Apparatus, 
Type JF, sold by Werner-Mathis, U.S.A., of Concord, N.C. The fabric is put 
through the jet nozzle then sewn at the ends to form an endless tube. The 
see-thru door is closed and then the fabric is scoured under conventional 
conditions at 160.degree. F. (71.1.degree. C.) for 15 minutes using 0.1 
g/l of MERPOL LFH.RTM. (a liquid nonionic detergent sold by E. I. du Pont 
de Nemours & Company) and 0.1 g/l of ammonium hydroxide. The fabric is 
overflow rinsed to remove all scouring agents and then the bath is 
dropped. 
The dyeing bath is then set with 2500 ml of distilled water at a 50:1 
liquor ratio (weight of bath to weight of fabric) at 80.degree. F. 
(26.7.degree. C.) and then the pH is adjusted to 5.0 with monosodium 
phosphate (MSP) and phosphoric acid. Under these conditions the fabric is 
fully flooded by the dyeing bath. The fabric is set into rapid motion by 
pumping the dyeing bath thru the jet nozzle. The temperature of the dyeing 
bath is then raised rapidly by 5.degree. F./min. (2.8.degree. C./min.) or 
greater to the dyeing temperature. In this example, the dyeing temperature 
is held nearly constant at about 200.degree. F. (93.3.degree. C.) during 
the dye addition period as the dye is added as described below. (The rapid 
dye uptake phase of this example begins with the addition of dye during 
the dye uptake phase, i.e., 100% of the dye is added during the rapid dye 
uptake phase.) 
Separately 0.5 g of Anthraquinone Milling Blue BL (C.I. Acid Blue 122) dye 
is dissolved in 200 ml of distilled water to form a dye concentrate. The 
amount of dye used is calculated to provide 1% dye-on-fiber assuming 
complete exhaustion of the dye. Using a precision (.about.1% accuracy) 
MANOSTAT COMPULAB liquid metering pump sold by Manostat Corporation of New 
York, N.Y., the separately prepared dye solution is metered under the 
surface of the dyeing bath away from the moving fabric at the rate of 5 
ml/minute which is equivalent to 0.025% dye/minute based on the weight of 
fabric. The percentage of total dye added per fabric turnover (machine 
cycle) is 0.08%. Under these conditions there is never any visible 
build-up of dye in the dyeing bath during the period of dye addition which 
is complete in 40 minutes. The dyeing bath is then cooled at 5.degree. 
F./min. (2.8.degree. C./min.) to 170.degree. F. (76.7.degree. C.), then 
the fabric is overflow rinsed, removed from the dyeing machine, then air 
dried. 
The result obtained is a level blue dyeing on the nylon warp knit and a 
colorless dyeing bath. 
EXAMPLE 2 
The amount and type of fabric and the dyeing equipment and procedure 
described in Example 1 are also used in this Example with the following 
dyes dissolved in 200 ml of distilled water to form the dye concentrate: 
0.247 g of C.I. Acid Yellow 184 
0.008 g of Nylanthrene Pink BLRF* 
FNT *Crompton & Knowles Corp., P.O. Box 33188, Charlotte, N.C. 28233) 
0.200 g of C.I. Direct Blue 86 
This is calculated to provide 0.9% dye-on-fiber assuming complete 
exhaustion of the dye. The dyeing solution is metered at the rate of 5 
ml/min. which is equivalent to 0.023% dye/minute based upon the weight of 
the fabric. The percentage of total dye added per fabric turnover (machine 
cycle) is 0.08%. Under these conditions there is a slight visible build up 
of dye at the end of the dye addition period which is completed in 40 
minutes. The dyeing bath is cooled at 5.degree. F./min. (2.8.degree. 
C./min.) to 170.degree. F. (76.7.degree. C.) at which time the bath is 
colorless and appears to be exhausted. The fabric is overflow rinsed, 
removed from the dyeing machine, then air dried. 
The result obtained is a level lime green dyeing on the nylon warp knit 
fabric and a colorless dyeing bath. 
EXAMPLE 3 
The amount and type of fabric and the dyeing equipment and procedure 
described in Example 1 are also used in this Example except that the 
dyeing bath is set at pH 4.0 with monosodium phosphate (MSP) and 
phosphoric acid and the dye used is 2.00 g of C.I Acid Black 107 dissolved 
in 400 ml of distilled water. This is calculated to provide 4.0% by weight 
of dye-on-fiber assuming complete exhaustion of the dye. 
The dyeing solution is metered at the rate of 20 ml/minute which is 
equivalent to 0.2% dye/minute based on weight of fabric. The percentage of 
total dye added per fabric turnover (machine cycle) is 0.17%. Under these 
conditions there is never any visible build up of dye in dyeing bath 
during the dye addition period which is complete in 20 minutes. The dyeing 
bath is cooled at 5.degree. F./min. (2.8.degree. C./min.) to 170.degree. 
F. (76.7.degree. C.). The fabric is overflow rinsed removed, and then air 
dried. 
The result obtained is a level black dyeing on the nylon warp knit fabric 
and a colorless dyeing bath. 
EXAMPLE 4 
The dyeing equipment described in Example 1 is used in this Example for 
dyeing a warp knit fabric from 80 weight % 40 denier trilobal 1.3 dpf 66 
nylon fiber and 20 weight % 40 denier LYCRA.RTM.) spandex (E. I. du Pont 
de Nemours and Company). In Part A, a conventional dyeing procedure is 
used. Parts B and C illustrate the process of the invention under 
different dyeing bath temperatures. Table 1 summarizes the results 
obtained. 
T A (Comparative) 
50 grams of the fabric described above is scoured under conventional 
conditions at 160.degree. F. (71.1.degree. C.) for 15 minutes using 0.1 
g/l of MERPOL LFH.RTM. and 0.1 g/l of ammonium hydroxide. The fabric is 
overflow rinsed to remove all scouring agents then the bath is dropped. 
The dyeing bath is set with 2500 ml of distilled water at 80.degree. F. 
(26.7.degree. C.) then the pH is adjusted to 5.0 with MSP and phosphoric 
acid. The fabric is set into rapid motion by the action of the jet nozzle. 
Separately 0.5 grams of C.I. Acid Blue 122 is dissolved in 200 ml of 
distilled water to provide 1% dye-on-fabric (1.25% on weight of nylon 
fiber) assuming complete exhaustion. The dye solution is then added to the 
dyeing bath. Under these conditions the fabric is fully flooded by the 
dyeing bath. The dyeing bath is raised at 2.degree. F./min. (1.1.degree. 
C./min.) to 200.degree. F. (93.3.degree. C.) then held at 200.degree. F. 
(93.3.degree. C.) for 30 minutes. The dyeing bath is cooled at 5.degree. 
F./min (2.8.degree. C.) to 170.degree. F. (76.7.degree. C.), the fabric is 
overflow rinsed, removed from the dyeing machine, then air dried. 
The result is a level blue dyeing on the nylon/LYCRA.RTM. spandex warp knit 
fabric and a completely colorless dyeing bath. The total cycle time is 
approximately 100 minutes. Relative dye strength is measured on the 
underlap side of the dried fabric and this fabric is designated as having 
100% relative dye strength. 
T B 
The amount and type of fabric, dyeing equipment and scouring conditions 
used in Part A are also used in this example. 
In this example the dyeing bath is set with 2500 ml of distilled water at 
80.degree. F. (26.7.degree. C.) then the pH is adjusted to 5.0 with MSP 
and phosphoric acid. Under these conditions the fabric is fully flooded by 
the dyeing bath. The fabric is set into rapid motion by pumping the dyeing 
bath thru the jet nozzle. The temperature of the dyeing bath is raised 
rapidly at about 5.degree. F./min. (2.8.degree. C./min.) to dyeing 
temperature. In this example the dyeing temperature is held nearly 
constant at 180.degree. F. (82.2.degree. C.) during the dye addition 
period. 
Separately 0.5 gm of C.I. Acid Blue 122 is dissolved in 200 ml of distilled 
water. This is calculated to provide 1% dye-on-fabric (1.25% on weight of 
nylon fiber) assuming complete exhaustion. Using equipment described in 
Example 1, the separately prepared dye solution is metered into the dyeing 
bath at the rate of 5 ml/minute which is equivalent to 0.025% dye/minute 
based upon weight of fabric while maintaining the dyeing temperature. The 
percentage of total dye added per fabric turnover (machine cycle) is 
0.08%. Under these conditions there is never any visible build-up of dye 
in the dyeing bath during the dye addition period which is completed in 40 
minutes. The dyeing bath is cooled at 5.degree. F./min. (2.8.degree. 
C./min.) to 170.degree. F. (76.7.degree. C.), then the fabric is overflow 
rinsed, removed from the dyeing machine, then air dried. 
The result obtained is a level blue dyeing on the nylon/LYCRA.RTM. spandex 
warp knit and a colorless dyeing bath. The total cycle time is 66 minutes 
which is 33% less than in Part A. In addition, relative dye strength 
measured for the blue color of the fabric (640 nm) is 36% higher than the 
fabric resulting from Part A. Color of fabric is measured on underlap 
side. 
T C 
The amount and type of fabric, dyeing equipment, and procedure described in 
Part B are also used in this example except the dyeing temperature is held 
nearly constant at 200.degree. F. (93.3.degree. C.) during the dye 
addition period while the dye is metered into the bath. 
The result obtained is a level blue dyeing on the nylon/LYCRA.RTM. spandex 
warp knit and a colorless dyeing bath. The total cycle time is 66 minutes 
which is 33% less than Part A. In addition, the relative dye strength 
measured for the blue color of the fabric (640 nm) is 65% higher than the 
fabric resulting from Part A. Color of fabric is measured on underlap 
side. 
TABLE 1 
______________________________________ 
Cycle time 
Bath Temp. Relative Dye 
Part (Minutes) .degree.F. 
(.degree.C.) 
Yield (%) 
______________________________________ 
A 100 200 (93.3)* 
100 
(Comparative) 
B 66 180 (82.2) 136 
C 66 200 (93.3) 165 
______________________________________ 
*Maximum temperature 
EXAMPLE 5 
The dyeing equipment described in Example 1 is also used in this Example 
for dyeing a circular knit, tubular fabric (41/2 in. tubular; 81/2 in. 
open width.times.62 in.) from a 40 denier, trilobal 3.08 dpf 66 nylon 
fiber with Anthraquinone Blue B (C.I. Acid Blue 45) used under conditions 
such that the dye transfers less than 10%. In Part A, a dyeing procedure 
is used in which all of the dye is present in the bath initially at low 
temperature and then the temperature is raised to complete the dyeing. 
Part B illustrates the process of the invention. The concentration of the 
dye in the bath is measured during the dyeings and Tables 2 and 3 list 
concentrations for Parts A and B, respectfully. 
T A (Comparative) 
35 grams of the fabric described above is scoured and rinsed as in Example 
1. The dyeing bath is then set as in Example 1 (70:1 liquor ratio, i.e., 
weight of bath to weight of fabric) at 80.degree. F. (26.7.degree. C.) and 
then the pH is adjusted to 4.5 with monosodium phosphate (MSP) and 
phosphoric acid. The fabric is set into rapid motion by the action of the 
jet nozzle. 
Separately 0.175 grams of C.I. Acid Blue 45 is dissolved in 200 ml of 
distilled water to provide 0.5% dye-on-fabric assuming complete 
exhaustion. All of the dye solution is then added to the dyeing bath at 
80.degree. F. (26.7.degree. C.). Under these conditions the fabric is 
fully flooded by the dyeing bath. The dyeing bath is raised at 2.degree. 
F./min. (1.1.degree. C./min.) to 140.degree. F. (60.degree. C.) then held 
at temperature for 30 minutes. Bath samples are taken at approximately 
10.degree. F. (5.6.degree. C.) temperature increments from 80.degree. F. 
(26.7.degree. C.) to 140.degree. F. (60.degree. C.). During the hold 
period at 140.degree. F. (60.degree. C.) bath samples are taken at 5 
minute intervals. Bath concentrations of C.I. Acid Blue 45 during this 
control procedure are shown in Table 2. 
The fabric is overflow rinsed, removed from the dyeing machine, then air 
dried. The result is a level blue dyeing on the circular knit fabric and a 
colorless dyeing bath. Relative dye strength is measured on the face of 
the dried fabric and this fabric is designated as having 100% relative dye 
strength. 
TABLE 2 
______________________________________ 
Time After 
Reaching Concentration 
Temperature 140.degree. F./60.degree. C. 
In Bath; Parts 
Sample .degree.F./(.degree.C.) 
(Minutes) Per Million 
______________________________________ 
1 80 (26.7) 42 
2 86 (30) 50 
3 95 (35) 47 
4 104 (40) 44 
5 113 (45) 41 
6 122 (50) 36 
7 131 (55) 32 
8 140 (60) 29 
9 5 16 
10 10 13 
11 15 7 
12 20 3 
13 25 2 
14 30 1 
______________________________________ 
T B 
The amount and type of fabric, scouring conditions, dyeing equipment are 
repeated in this example of the invention. 
In this example of the invention, the dyeing bath is set as in Part A. The 
fabric is set into rapid motion by pumping the dyeing bath thru the jet 
nozzle and the temperature of the dyeing bath is raised rapidly by 
5.degree. F./min. (2.8.degree. C./min.). In this example, the dyeing 
temperature is held at 140.degree. F. (60.degree. C.) during the dye 
addition period. 
Separately 0.175 g of Anthraquinone Blue B (C.I. Acid Blue 45) dye is 
dissolved in 100 ml of distilled water. This is calculated to provide 0.5% 
dye-on-fiber assuming complete exhaustion of the dye. Using the equipment 
described in Example 1, the separately prepared dye solution is metered 
under the surface of the dyeing bath, with the bath at 140.degree. F. at 
the rate of 5 ml/minute, over a 20 minute dye addition period which is 
equivalent to 0.025% dye/minute based on the fabric weight. The percentage 
dye added per fabric turnover (machine cycle) is 0.17%. Samples of the 
dyeing bath are taken after 25 ml, 50 ml, 75 ml and 100 ml of dye are 
metered in. Bath samples are also taken 5, 10, 15, 20, 25 and 30 minutes 
after all the dye solution is metered in. The concentrations of dye in 
these samples are measured and the results are reported in Table 3. Then, 
the fabric is overflow rinsed, removed from the dyeing machine, and air 
dried. 
The result obtained is a level blue dyeing on the nylon circular knit and a 
colorless dyeing bath. An increase in relative dye yield of 12 to 15% is 
measured on the face of the dried fabric with respect to comparative 
dyeing described in Part A above. 
TABLE 3 
______________________________________ 
Time 
After All Concentration 
Bath M1 of Dye Dye Added In Bath; Parts 
Sample Concentrate Added 
(Minutes) Per Million 
______________________________________ 
1 25 0.40 
2 50 1.08 
3 75 1.6 
4 100 2.1 
5 125 1.9 
6 150 3.1 
7 175 4.3 
8 200 4.1 
9 5 2.9 
10 10 1.6 
11 15 1.1 
12 20 0.7 
13 25 0.5 
14 30 0.4 
______________________________________ 
EXAMPLE 6 
The dyeing equipment in Example 1 is also used in this Example for dyeing a 
warp knit (8 in. open width.times.70 in.) from a 50 denier, round 2.9 dpf 
66 nylon fiber with a four component pre-metallized dye mixture. In Part 
A, a conventional dye procedure is used and, in Part B, a process in 
accordance with the invention is used. Dye uniformity ratings from the two 
dyeings are compared. 
T A (Comparative) 
54 grams of the fabric described above is scoured and the dye bath set as 
in Example 1 to make a 45:1 liquor ratio (weight of bath to weight of 
fabric). The pH is adjusted to 5.0 with MSP and phosphoric acid and the 
fabric is set into rapid motion by the action of the jet nozzle. 
Separately 0.028 grams of Intralan Yellow 2BRL S (Crompton and Knowles 
Corp.) (100%) and 0.0084 grams of Intralan Bordeaux RLB (Crompton and 
Knowles Corp.) (100%); and 0.06 grams of C. I. Acid Black 107 and 0.18 
grams of C. I. Acid Black 132, all pre-metallized dyes, are dissolved in 
200 ml of distilled water. This is calculated to provide dye-on-fiber of 
0.0518%; 0.0156%; 0.11% and 0.33% of each of the respective dyes, assuming 
complete exhaustion of the dye. The dye solution is then added to the 
dyeing bath in the conventional manner at 80.degree. F. (26.7.degree. C.). 
Under these conditions the fabric is fully flooded by the dyeing bath. The 
dyeing bath is raised at 2.degree. F./min. (1.1.degree. C./min.) to 
205.degree. F. (96.1.degree. C.) then held at temperature for 30 minutes. 
The fabric is overflow rinsed, removed from the dyeing machine, then air 
dried. 
The result is a colorless dyeing bath and a level (i.e., not blotchy) gray 
dyed warp knit fabric but with numerous light and dark streaks and bands. 
The dye uniformity rating for this fabric is 2.0. Relative dye strength 
is measured on the underlap side of the dried fabric and this fabric is 
designated as having 100% relative dye strength. 
T B 
The amount and type of fabric, dyeing equipment, and scouring conditions as 
in Part A are also used in this example. 
The dyeing bath is then set as in Example 1 at and the pH is adjusted to 
5.0 with monosodiumphosphate (MSP) and phosphoric acid. Under these 
conditions the fabric is fully flooded by the dyeing bath. The fabric is 
set into rapid motion by pumping the dyeing bath thru the jet nozzle. The 
temperature of the dyeing bath is raised rapidly by 5.degree. F./min. 
(2.8.degree. C./min.) to 205.degree. F. (96.1.degree. C.). 
Separately the same four component dye shade detailed in the Part A is 
prepared in 200 ml of distilled water to provide the same percentages of 
dyes, dye-on-fabric, assuming complete exhaustion. Using the same 
equipment as used in Example 1, the separately prepared dye solution is 
metered under the surface of the dyeing bath, with the bath at 205.degree. 
F. (96.1.degree. C.), at the rate of 5 ml/minute, over the 40 minute dye 
addition period. The percentage of total dye added per fabric turnover 
(machine cycle) is 0.08%. Then the fabric is overflow rinsed, removed from 
the dyeing machine, then air dried. 
The result obtained is a level (i.e., not blotchy) gray dyeing with no 
noticeable streaks and a colorless dyeing bath. An increase in relative 
dye yield of 34% is measured on the underlap side with respect to the 
comparative dyeing described above in Part A. This fabric has a dye 
uniformity rating of 7.5. 
EXAMPLE 7 
The dyeing equipment described in Example 1 is used in this Example for a 
circular knit, tubular fabric (41/2 in. tubular, 81/2 in. open 
width.times.62 in.) from a 40 denier, trilobal 3.08 dpf 66 nylon fiber 
with Anthraquinone Milling Blue BL (C.I. Acid Blue 122) dye. In part A, a 
conventional dyeing procedure is used. Parts B, C and D illustrate 
processes in accordance with the invention where some of the dye is added 
into the bath before the bath is up to temperature, i.e., less than 100% 
of the dye is added into the bath during the rapid dye uptake phase. 
T A (Comparative) 
50 grams of the fabric described above is scoured and overflow rinsed as in 
Example 1. The dyeing bath is again set as in Example 1 (50:1 liquor 
ratio) and the pH is adjusted to 5.0 with MSP and phosphoric acid. The 
fabric is set into rapid motion by the action of the jet nozzle. 
Separately 0.5 grams of C.I. Acid Blue 122 is dissolved in 200 ml of 
distilled water to provide 1% dye-on-fabric assuming complete exhaustion. 
The dye solution is then added to the dyeing bath in the conventional 
manner at 80.degree. F. (26.7.degree. C.). Under these conditions the 
fabric is fully flooded by the dyeing bath. The dyeing bath raised at 
2.degree. F./min. (1.1.degree. C./min.) 200.degree. F. (93.3.degree. C.) 
then held at 200.degree. F. (93.3.degree. C.) for 30 minutes. The dyeing 
bath is cooled at 5.degree. F./min (2.8.degree. C.) to 170.degree. F. 
(76.7.degree. C.), the fabric is overflow rinsed, removed from the dyeing 
machine, and then air dried. 
The result is a level blue dyeing on the circular knit fabric and a 
colorless dyeing bath. The total cycle time is approximately 100 minutes. 
Relative dye strength is measured on the face of the dried fabric and this 
fabric designated as having 100% relative dye strength. 
T B 
The type of fabric, the dyeing equipment and scouring procedures of Part A 
are repeated in this example except with 35 grams of the fabric. 
The dyeing bath is then set at 80.degree. F. (26.7.degree. C.) and then the 
pH is adjusted to 5.0 with monosodium phosphate (MSP) and phosphoric acid. 
The fabric is set into rapid motion by the action of the jet nozzle. 
Separately 0.35 g of Anthraquinone Milling Blue BL (C.I. Acid Blue 122) dye 
is dissolved in 200 ml of distilled water to provide 1% dye-on-fiber 
assuming complete exhaustion of the dye. 40 ml of the 200 ml of the 
separately prepared dye solution (20% of the total) is diluted to 125 ml 
is metered under the surface of the dyeing bath as in Example 1, with the 
bath at 80.degree. F. (26.7.degree. C.), at the rate of 5 ml/minute over 
25 minutes while the bath temperature is raised to 205.degree. F. 
(96.1.degree. C.) at 5.degree. F./min (2.8.degree. C./min.). In this 
Example, the beginning of the dye addition period does not coincide with 
the beginning of the rapid dye uptake phase which begins when the dye 
transition temperature is reached. There is a noticeable build-up of dye 
in the bath under these conditions. 
When the bath reached 205.degree. F. (96.1.degree. C.), which is well above 
the dye transition temperature, the remaining 160 ml of the original dye 
solution (80% of the total), diluted to 200 ml, is metered under the 
surface of the dyeing bath at the rate of 5 ml/min. over 40 minutes. Thus, 
at least about 80% of the dye is added during the rapid dye uptake phase 
when the bath is above the dye transition temperature. The percentage of 
total dye added per fabric turnover (machine cycle) during this period in 
which the second volume of dye is metered is 0.067%. The dyeing bath is 
then cooled, the dyed fabric overflow rinsed, removed from the dyeing 
machine, air dried as in Example 1. 
The result obtained is a level blue dyeing on the nylon warp knit and a 
colorless dyeing bath. The total cycle time is approximately 72 minutes. 
An increase in relative dye yield of 27% is measured on the face of the 
dried fabric compared to the comparative dyeing of Part A described above. 
T C 
The amount and type of fabric and the dyeing equipment and procedure 
described in Part B are used except that 70 ml of the original 200 ml 
solution of dye (35%) is diluted to 125 ml. This diluted solution is 
metered at the rate of 5 ml/min., as in Part B, starting with the bath at 
80.degree. F. (26.7.degree. C.) while raising the bath temperature to 
205.degree. F. (96.1.degree. C.) at 5.degree. F./min. (2.8.degree. 
C./min.) over 25 minutes. There is a noticeable build-up of dye in the 
bath. 
When the bath reached 205.degree. F. (96.1.degree. C.), the remaining 130 
ml of the original dye solution (65%), diluted to 200 ml, is metered at 
the rate of 5 ml/min. over 40 minutes. Thus, at least about 65% of the dye 
is added to the bath during the rapid dye uptake phase. The percentage of 
total dye added per fabric turnover (machine cycle) during this period in 
which the second volume of dye is metered is 0.054%. 
The dyeing bath is cooled, the dyed fabric overflow rinsed, removed from 
the dyeing machine, and air dried as in Part B with equivalent results 
except that the increase in dye yield is now 21% compared to the 
conventional control dyeing. The total cycle time is approximately 72 
minutes. 
T D 
The amount and type of fabric and the dyeing equipment and procedure 
described in Part B is repeated except that 100 ml of the original 200 ml 
solution of dye (50%) is diluted to 125 ml. This diluted solution is 
metered at the rate of 5 ml/min., as in Part B, starting with the bath at 
80.degree. F. (26.7.degree. C.) while raising the bath temperature to 
205.degree. F. (96.1.degree. C.) at 5.degree. F./min. (2.8.degree. 
C./min.) over 25 minutes. There is a noticeable build-up of dye in the 
bath. 
When the bath reached 205.degree. F. (96.1.degree. C.), the remaining 100 
ml of the original dye solution (50%) diluted to 200 ml is metered at the 
rate of 5 ml/min. over 40 mins. Thus, at least about 50% of the dye is 
added during the rapid dye uptake phase. The percentage of total dye added 
per fabric turnover (machine cycle) during this period in which the second 
volume of dye is metered is 0.042%. The dyeing bath is cooled, the dyed 
fabric overflow rinsed, removed from the dyeing machine, and air dried as 
in Part B with equivalent results except that the increase in dye yield is 
now 11% compared to the conventional control dyeing. The total cycle time 
is approximately 72 minutes. 
EXAMPLE 8 
The dyeing equipment described in Example 1 is used for dyeing a jersey 
fabric tubing knit from trilobal 2.25 dpf 66 nylon yarn using a 
Lawson-Hemphill laboratory knitting machine. In Part A, a conventional 
dyeing procedure is used. Part B illustrates the process of the invention 
used to obtain a relative dye strength roughly equivalent to the dyed 
fabric of Part A with less dye being used in the process. (A lower 
relative dye content in the resulting fabric is also observed.) 
Cross-sectional photomicrographs of the dyed fabrics are made. FIG. 5 and 
7 illustrates the fabric dyed by a conventional dyeing process (Part A) 
and FIG. 4 and 6 illustrates the fabric dyed by a process in accordance 
with the invention. 
T A (Comparative) 
A 50 gram sample of the fabric described above is scoured, rinsed and the 
set with 2500 ml of distilled water and the pH is adjusted to 5.0 as in 
Example 1. The fabric is set into rapid motion by the action of the jet 
nozzle and run for 5 minutes. 
Separately 1.5 g of C.I. Acid Blue 335 dye is dissolved in water to make a 
liquid concentrate. This is calculated to provide 3.0% dye-on-fiber 
assuming complete exhaustion. The concentrated dye solution is added to 
the bath. Under these conditions the fabric is fully flooded by the dyeing 
bath. The temperature is then raised to 205.degree. F. (96.1.degree. C.) 
at 3.degree. F./min. (1.7.degree. C./min.) and the fabric is dyed for 30 
minutes. The bath is cooled, the fabric rinsed and air dried. 
The result is a colorless dye bath and a level, navy blue fabric. Its 
relative dye strength taking an average of the face and back of the tubing 
and its relative dye content are each designated being 100%. FIGS. 5 and 7 
are cross-sectional photomicrographs of the fabric. 
T B 
With a 50 g sample of the fabric described above, the dyeing bath is then 
set with 2500 ml of distilled water and the pH is adjusted to 5.0 as in 
Example 1. The fabric is set into rapid motion by pumping the dyeing bath 
thru the jet nozzle. The temperature of the dyeing bath is then raised 
rapidly at 6.degree. F./min. (3.3.degree. C./min.) to the dyeing 
temperature. In this example, the temperature is held at 207.degree. F. 
(97.2.degree. C.) during the dye addition period. 
Separately 1.05 g of C.I. Acid Blue 335 dye is dissolved in 200 ml of 
distilled water. This is calculated to provide 2.1% dye-on-fiber assuming 
complete exhaustion. Using the equipment described in Example 1, the 
separately prepared dye solution is metered under the surface of the 
dyeing bath, away from the moving fabric, at the rate of 5 ml/minute, 
which is equivalent to 0.05% dye/minute based on the weight of fabric. The 
percentage of total dye added per fabric turnover (machine cycle) is 
0.08%. Under these conditions, there is never any visible built-up of dye 
in the bath during the period of dye solution addition which is completed 
in 42 minutes. The bath containing the dyed fabric is then cooled, the 
fabric is overflow rinsed, removed from the dyeing machine, and finally 
air dried as in Example 1. 
The result is a colorless dye bath and a level, navy blue fabric. The 
relative dye strength of the fabric taking an average of the face and the 
back is 99.8%, roughly equivalent to the fabric of Part A, while its 
relative dye content is 73%. This is equivalent to a relative dye yield 
increase of 36.7%. FIGS. 4 and 6 are the cross-sectional photomicrograph 
of this fabric. 
EXAMPLE 9 
The dyeing equipment and procedures described in Example 1 is also used in 
this Example for dyeing a circular knit tubular fabric knit from 20/2 
cotton count, 3 dpf, 1.5 inch long, autoclave crimp-set staple nylon yarn 
with the following dyes (% based on weight of fabric) together with the 
indicated UV inhibitor: 
______________________________________ 
0.0275% C.I. Acid Red 316 
0.2145% C.I. Acid Blue 239 
0.1045% Avilon Blue RW* 
0.066% C.I. Acid Black 132 
1.100% CIBAFAST N .RTM.* (UV inhibitor) 
______________________________________ 
*Ciba Geigy Corp. 
The result is a cobalt blue color fabric with the outside being more deeply 
dyed than the inside and a colorless dyeing bath. The relative dye yield 
calculated from the average K/S value (average of the face and back 
surfaces of the knit tubing) increased by 76% compared to a control fabric 
dyed with the same dyes using a conventional procedure in a beck dyer. The 
relative dye content of the fabrics is roughly the same at 100% 
(invention) and 100.5% (control). 
EXAMPLE 10 
In this example, a carpet tufted from 2 ply, 1150 denier, trilobal 17 dpf 
bulked, continuous filament nylon yarn are dyed in an 8 inch Saucier 
Beck-dyeing Machine, manufactured by Saucier Stainless Steel Products, 
Minneapolis, Minn. Part A illustrates a conventional procedure and Part B 
illustrates a process of the invention. 
T A (Comparative) 
The 450 grams of a carpet (8 in. by 75 in.) carpet as described above is 
placed over the winch of this beck, then sewn at the ends to form an 
endless "rope." The door is closed and then the carpet is scoured at 
160.degree. F. (71.1.degree. C.) for 15 minutes using 0.1 g/l of MERPOL 
LFH.RTM. (a liquid non-ionic detergent sold by E. I. du Pont de Nemours & 
Company) and 0.1 g/l of ammonium hydroxide. The fabric is overflow rinsed 
to remove all scouring agents, then the batch is dropped. 
The dyeing bath is then set with 25 liters of distilled water at 55:1 
liquor ratio (weight of bath to weight of fabric) at 80.degree. F. 
(26.7.degree. C.) and then the pH is adjusted to 5.0 with monosodium 
phosphate (MSP) and phosphoric acid. The fabric is set in motion by the 
turning action of the winch-reel. 
Separately 4.5 grams of Anthraquinone Milling Blue BL (C.I. Acid Blue 122) 
is dissolved in 1000 ml of distilled water to provide 1% dye-on-fabric 
assuming complete exhaustion. The dye solution is then added to the dyeing 
bath. The dyeing bath is raised at 2.degree. F./min. (1.1.degree. C./min.) 
to 205.degree. F. (96.1.degree. C.) then held at 205.degree. F. 
(96.1.degree. C.) for 30 minutes. The dyeing bath is cooled at 5.degree. 
F./min. (2.8.degree. C.) to 170.degree. F. (76.7.degree. C.), the fabric 
is overflow rinsed, removed from the dyeing machine, then air dried. 
The result is a level blue dyeing on the nylon carpet and a colorless 
dyeing bath. Relative dye strength is measured on the face of the tufted 
carpet and this carpet is designated as having 100% relative dye strength. 
T B 
The amount and type of carpet, dyeing equipment, and scouring conditions 
used in Part A are again used in this Example. 
In this Example, dyeing bath is again set with a 55:1 liquor ratio at 
80.degree. F. (26.7.degree. C.) and then the pH is adjusted to 5.0 with 
monosodium phosphate (MSP) and phosphoric acid. The fabric is set in 
motion by the turning action of the winch-reel. The temperature of the 
dyeing bath is then raised rapidly by 5.degree. F./min. (2.8.degree. 
C./min.) to the dyeing temperature. In this example, the dyeing 
temperature is held nearly constant at about 200.degree. F. (93.3.degree. 
C.) during the dye addition period as described below. 
Separately 4.5 g of Anthraquinone Milling Blue BL (C. I. Acid Blue 122) dye 
is dissolved in 1000 ml of distilled water to provide -1% dye-on-fiber 
assuming complete exhaustion of the dye. Using a precision (.about.1% 
accuracy) MANOSTAT COMPULAB liquid metering pump sold by Manostat 
Corporation of New York, N.Y., the separately prepared dye solution is 
metered under the surface of the dyeing bath away from the moving fabric 
at the rate of 25 ml/minute which is equivalent to 0.025% dye/minute based 
on the weight of the fabric. The percentage of total dye added per carpet 
turnover is 0.08%. Under these conditions there is never any visible 
buildup of dye in the dyeing bath during the dye addition period which is 
complete in 40 minutes. 
The dyeing bath is then cooled at 5.degree. F./min. (2.8.degree. C./min.) 
to 170.degree. F. (76.7.degree. C.), then the fabric is overflow rinsed, 
removed from the dyeing machine, then air dried. 
The result obtained is a level blue dyeing on the carpet and a colorless 
dyeing bath. The dye yield is increased by 98% relative to the comparative 
sample prepared in Part A above. 
EXAMPLE 11 
In this example, a carpet tufted from 3.75 cotton count, trilobal, 18 dpf, 
bulked, staple nylon yarn is dyed in the same equipment as used in Example 
10. Part A illustrates a conventional procedure and Part B illustrates a 
process in accordance with the invention. 
T A (Comparative) 
The 560 grams of a carpet (9 inches by 60 inches) as described above is 
scoured and rinsed as in Example 10. 
The dyeing bath is then set with 11,000 ml of distilled water at 20:1 
liquor ratio (weight of bath to weight of carpet) at 80.degree. F. 
(26.7.degree. C.) and then the pH is adjusted to 6.0 with monosodium 
phosphate (MSP). The carpet is set in motion by the turning action of the 
winch-reel. 
Separately 0.84 grams each of C.I. Acid Orange 156, C.I. Acid Red 361 and 
C.I. Acid Blue 277 are dissolved in 100 ml of distilled water to provide 
0.45% dye-on-carpet assuming complete exhaustion of the dye. The dye 
solution is then added to the dyeing bath. The dyeing bath is raised at 
3.degree. F./min. (1.7.degree. C./min. to 212.degree. F. (100.degree. C.) 
then held at 212.degree. F. (100.degree. C.) for 1 hour. The dyeing bath 
is dropped while at 212.degree. F. (100.degree. C.), the carpet is 
overflowed rinsed with cold water and the dyeing bath is dropped again. 
The carpet is removed from the dyeing machine, water extracted and then 
air dried. 
The result is a level medium brown dyeing on the nylon carpet and a 
colorless dyeing bath. 
T B 
The amount and type of carpet, dyeing equipment and scouring conditions 
used in Part A are again used in this Example. 
In this Example, dyeing bath is again set with 1,000 ml of distilled water 
at 20:1 liquor ratio (weight of bath to weight of carpet) at 80.degree. F. 
(26.7.degree. C.) and then the pH is again adjusted to 6.0 with monosodium 
phosphate (MSP), trisodiumpyrophosphate (TSPP) and phosphoric acid. With 
the carpet moving by the turning action of the winch-reel, the temperature 
of the dyeing bath is then raised rapidly by approximately 5.degree. 
F./minute (2.8.degree. C./minute) to the dyeing temperature 212.degree. F. 
(100.degree. C.). 
Separately 0.84 grams each of C.I Acid Orange 156, C.I. Acid Red 361, and 
C.I. Acid Blue 277 are dissolved in 100 ml of distilled water and then 
diluted to a total volume of 200 ml to provide 0.45% dye-on-carpet 
assuming complete exhaustion of the dye. 
Using a precision (.about.1% accuracy) MANOSTAT COMPULAB liquid metering 
pump sold by Manostat Corporation of New York, N.Y., the separately 
prepared dye solution is metered under the surface of the dyeing bath away 
from the moving carpet at the rate of 5 ml/min. which is equivalent to 
0.011% dye/minute based on the weight of the carpet. The percentage of 
total dye added per carpet turnover (machine cycle) is 0.08%. Under these 
conditions there is never any visible buildup of dye in the dyeing bath 
during the period of dye addition which is completed in 40 minutes. After 
completion of dye addition, the bath is run for 15 minutes at about 
212.degree. F. (100.degree. C.). The hot dyeing bath is dropped, the 
carpet is overflowed rinsed with cold water and the dyeing bath is dropped 
again. The carpet is removed from the dyeing machine, water extracted and 
then air dried. 
The result is a level medium brown dyeing on the nylon carpet and a 
colorless dyeing bath. 
EXAMPLE 12 
25 grams of a woven fabric (64 in. long'81/2 in. wide) from a warp of 40 
denier, round 1.18 dpf, semi-dull 66 nylon fiber and a filling of 2 ply, 
50 denier, 0.76 dpf, round, semi-dull 66 nylon Air-Jet textured yarns are 
sewn to form a tube and are scoured and dyed with Anthraquinone Milling 
Blue BL (C.I. Acid Blue 122) as in Example 4, Part A (Comparative) to 
provide a comparative dyeing. In addition, the same fabric is scoured and 
dyed with the same dye in accordance with the procedures of Example 4, 
Part B to provide a dyeing in accordance with the invention. 
The resulting level blue dyeing on the nylon woven fabric in accordance 
with the invention showed an increase in dye yield of 12 to 15% on the 
face of the fabric relative to the comparative (control) dyeing. 
Photomicrographs showed that the fiber of the dyes fabric is 
asymmetrically ring-dyed, typical of the preferred form of invention using 
dyes such that the transfer is less than 10%. 
EXAMPLE 13 
In this Example, conditions are varied to illustrate the effects on dye 
uptake during the process and on dye yield of the dyed fabric. pH (4 vs. 
6), temperature (180 vs. 205.degree. F.; 82.2 vs. 96.1.degree. C.) and 
time at temperature after addition of dye (15 vs. 45 minutes) are varied 
as detailed in Table 4. 
For Items 1-7, the amount and type of fabric, the dyeing equipment and 
procedure detailed in Example 5, Part B are repeated first to scour the 
fabric and then to apply 2% on weight of fabric of C.I. Acid Violet 48. 
The pH is adjusted to 4 or 6 as shown in Table 4 with monosodium phosphate 
(MSP) and phosphoric acid. A previously prepared solution of 0.70 g C.I. 
Acid Violet 48 in 200 ml of distilled water is added to the dyeing bath at 
a rate of 5 ml/minute and samples of the dyeing bath are collected at 
various temperatures/times during the process. The amount of dye per 
minute is 0.05% dye/minute and percentage of total dye added per fabric 
turnover (machine cycle) is 0.08%. The concentration of C.I. Acid Violet 
48 is determined spectrophotometrically and the results are summarized in 
FIG. 1 for Items 1 (pH 4) and 5 (pH 6) illustrating the 15 minute time at 
temperature. 
Four comparative Items 1c, 2c, 3c, and 4c are prepared using the same type 
and amount of fabric used for Items 1-7. The same procedures are used for 
scouring and preparing the items for dyeing. Four control dyeings are run, 
one at each of the pH and temperature conditions of Items 1-7, namely: 
1c pH 4; 180.degree. F. (82.2.degree. C.); 
2c pH 4; 205.degree. F. (96.1.degree. C.); 
3c pH 6; 180.degree. F. (82.2.degree. C.); 
4c pH 6; 205.degree. F. (96.1.degree. C.). 
The same liquid dye concentrate is used as in Items 1-8, but for each of 
the Items 1c-4c, the dye is added and the dyeing bath is raised at 
2.degree. F./min. (1.1.degree. C./min.) to the specified temperature, then 
held at temperature for 30 minutes. 
For Items 2c and 4c, bath samples are collected at various 
temperatures/times during the dyeing. The concentration of C.I. Acid 
Violet 48 is determined and the results are summarized in FIG. 2. The bath 
is cooled at 5.degree. F. (2.8.degree. C.) to 170.degree. F. (76.7.degree. 
C.), then the dyed fabric is overflow rinsed by addition of cool water, 
removed from the dyeing machine and air dried. 
The dye strength of each Item 1-7 are measured on the face of the fabric 
against its respective control. Results are detailed in Table 4. 
TABLE 4 
______________________________________ 
TEMPER- TIME % DYE 
ATURE AT YIELD 
ITEM COMP. PH .degree.F. 
(.degree.C.) 
TEMP. INCREASE 
______________________________________ 
1 1c 4 180 (82.2) 
15 41 
2 1c 4 180 (82.2) 
45 34 
3 2c 4 205 (96.1) 
15 49 
4 2c 4 205 (96.1) 
45 46 
5 3c 6 180 (82.2) 
15 4 
6 4c 6 205 (96.1) 
15 13 
7 4c 6 205 (96.1) 
45 9 
______________________________________ 
EXAMPLE 14 
The amount and type of fabric and the dyeing equipment and procedure 
detailed in Example 13, Items 1-7 is repeated first to scour the fabric 
and then to apply 2% on weight of fabric of C.I. Acid Violet 48. The rate 
of dye addition is decreased to illustrate the effects on dye uptake 
during the processes and on dye yield of the dyed fabric compared with the 
rate in Example 13. Items 1 and 2 with different temperature (180 vs. 
205.degree. F.; 82.2 vs. 96.1.degree. C.) at pH 6 are illustrated. 
In this example, the dyeing baths are set and the pH is adjusted to 6 with 
monosodium phosphate (MSP) and phosphoric acid. The same amount of dye, 
0.70 g of C.I. Acid Violet 48, is dissolved in 400 ml of distilled water 
and added at 5 ml/min. into the bath. Since the amount of dye is the same 
but the volume of solution is doubled, the rate of addition is half the 
rate of Example 13; i.e., 0.025% dye/minute and 0.04% total dye per 
turnover. Samples of the dyeing bath are collected at various times during 
the process and up to minutes after completion of addition of dye in the 
bath and the concentration of C.I. Acid Violet 48 is determined 
spectrophotometrically and the results are summarized in FIG. 3. 
EXAMPLE 15 
Using larger scale dyeing equipment, full width (60 inches) elastic and 
non-elastic warp knit tricot fabric and half width (63 inches) elastic 
warp knit raschel fabric are dyed by the process of this invention. Part I 
illustrates the process used to prepare the fabrics prior to dyeing and 
Parts II, III and IV illustrate the dyeing of these types of fabrics. 
T I 
The warp knit fabrics described in this example are prepared for dyeing 
using an open width scouring range sold by Jawetex Ag of Rorschasch, 
Switzerland. The fabrics are processed at 10 yards/minute through the wash 
tank holding 2,000 liters of water at 180.degree. F. (82.2.degree. C.), 
which contained 0.5 gram/liter of MERPOL LFH.RTM. (a liquid non-ionic 
detergent sold by E. I. Du Pont de Nemours & Company, Inc. of Wilmington, 
Del.) then through the rinse tank holding 540 liters of water heated to 
the same temperature. The scoured fabrics are dried and heat set in one 
pass at 385.degree. F. (196.1.degree. C.) for 30 seconds using a 4 box (10 
feet each) pin tenter sold by Bruckner Machinery Corp. of Spartanburg, 
S.C. The edges are trimmed during heat setting to minimize edge curling 
during dyeing. 
T II 
9,000 grams of warp knit fabric (75 linear yards; 60 inch width) from a 40 
denier, trilobal 3.1 dpf 66 nylon fiber, after preparation as described in 
Part I, are introduced into a fully-flooded Hisaka Jet Dyer, Model V-L 
sold by Mascoe Systems Corp. of Mauldin, S.C. The fabric is put through 
the jet nozzle (70 mm) then sewn carefully at the ends to avoid bias 
seaming. The fabric is scoured under conventional conditions at 
180.degree. F. (82.2.degree. C.) for 20 minutes using 400 liters of water 
containing 0.5 g/l of MERPOL LFH.RTM.. The fabric is overflow rinsed to 
remove all scouring chemicals. 
The dyeing bath is then set with 400 liters of water at a 44:1 liquor ratio 
(weight of bath to weight of fabric) at 80.degree. F. (26.7.degree. C.) 
then the pH is adjusted to 5.2 with 0.4 g/l of monosodium phosphate (MSP). 
Under these conditions the fabric is fully flooded by the dyeing bath. The 
fabric is set into motion (1 turnover/min) by pumping the dyeing bath 
through the jet nozzle (8 pounds pressure). The temperature of the dyeing 
bath is raised rapidly by 7.degree. F./min. (3.9.degree. C./min.) to the 
dyeing temperature. In this example, the dyeing temperature is held nearly 
constant at about 180.degree. F. (82.2.degree. C.) during the dye addition 
period as described below. 
Separately 90.0 grams of Anthraquinone Milling Blue BL (C. I. Acid Blue 
122) is dissolved in 9 liters of warm water. This is calculated to provide 
1% dye-on-fabric assuming complete exhaustion of the dye. Using a 
(.about.1% accuracy) MANOSTAT COMPULAB liquid metering pump sold by 
Manostat Corporation of New York, N.Y., the separately prepared dye 
solution (10 g/l) is metered into the dyeing machine at the inlet of the 
circulation pump. A pumping rate of 225 ml/min. is used, which is 
equivalent to 0.025% dye/minute based on weight of fabric. The percentage 
of total dye added per fabric turnover (machine cycle) is 1.67%. Under 
these conditions there is only a slight visible build up of dye during the 
period of dye addition which is complete in 40 minutes. After an 
additional 10 minutes the dyeing bath is colorless and the pH is 5.5. The 
dyeing bath is then cooled at 5.degree. F./min. (2.8.degree. C./min.), 
overflow rinsed, removed from the dyeing machine and then dried at wet 
width on a pin tenter at 250.degree. F. (121.1.degree. C.). Visual 
inspection of the dyed fabric showed a level dyeing. 
T III 
The fabric preparation described in Part I and the dyeing procedure 
described in Part II of this example are used to dye 12,600 grams (51 
linear yards; 60 inches width) of a warp knit tricot fabric from 80 weight 
% 40 denier trilobal 3.1 dpf 66 nylon fiber and 20 weight % 40 denier 
LYCRA.RTM. spandex (E. I. Du Pont de Nemours & Company, Inc.). 
Separately, 126.0 grams of Anthraquinone Milling Blue BL (C.I. Acid Blue 
122) are dissolved in 12.6 liters of warm water. This is calculated to 
provide 1% dye-on-fabric (1.25% on weight of nylon fiber) assuming 
complete exhaustion of the dye. The separately prepared dye solution (10 
g/l) is metered at 315 ml/min., which is equivalent to 0.025% dye/minute. 
The percentage of total dye added per fabric turnover (machine cycle) is 
1.67%. Visual inspection of the dyed fabric showed a level dyeing. 
T IV 
The fabric preparation described in Part I and the dyeing procedure 
described in Part II of this example are used to dye 11,200 grams (44 
linear yards; 63 inch width) of a warp knit raschel fabric from 87 weight 
% 40 denier trilobal 3.1 dpf 66 nylon and 13 weight % 140 denier 
LYCRA.RTM. spandex (E. I. du Pont de Nemours & Company, Inc.). 
Separately, 112.0 grams of Anthraquinone Milling Blue BL (C. I. Acid Blue 
122) are dissolved in 1.2 liters of warm water. This is calculated to 
provide 1% dye-on-fabric (1.15% on weight of nylon fiber) assuming 
complete exhaustion of dye. The separately prepared dye solution (10 g/l) 
is metered at 5 ml/min., which is equivalent to 0.021% dye/minute. The 
percentage of total dye added per fabric turnover (machine cycle) is 
1.67%. Visual inspection of the dyed fabric showed a level dyeing. 
EXAMPLE 16 
200 yards (100 lbs.) of a 93 inch Wide warp knit fabric from a 50 denier, 
round 2.9 dpf 66 nylon fiber is introduced into a Hisaka FL-1 Jet Dyeing 
Machine sold by Mascoe Systems Corp. of Mauldin, S.C. containing 325 
liters of water to a liquor:fabric ratio of about 7:1. Under these 
conditions, the fabric is only partially immersed. The bath is set with 
0.5%, on weight of fabric, of trisodium pyrophosphate and 0.5%, on weight 
of fabric, of POLYSCOUR LF.RTM. a detergent manufactured by Apollo 
Chemical Co., Burlington, N.C. The bath temperature is raised to 
180.degree. F. (82.2.degree. C.) at 5.degree. F. (2.8.degree. C.) per 
minute. The fabric is scoured for 10 minutes at 180.degree. F. 
(82.2.degree. C.) then rinsed. A fresh bath is set at 80.degree. F. 
(26.7.degree. C.) and 0.2% on weight of fabric of ALBEGAL B.RTM., a 
leveling agent manufactured by Ciba Geigy Corp., Greensboro, N.C., and 
0.349% on weight of fabric of monosodium phosphate are added. The 
temperature is raised to 200.degree. F. (93.3.degree. C.) at 5.degree. F. 
(2.8.degree. C.) to 7.degree. F. (3.9.degree. C.) per minute. Fabric 
turnover rate is 30 seconds per revolution during the entire process. 
Separately, the following dyes and 1.5% CIBAFAST N.RTM., an ultraviolet 
light absorber manufactured by Ciba Geigy Corp, are mixed in 19 liters of 
water with % being based on fabric weight: 
______________________________________ 
1.05119% Intralan Yellow 3RL* 
0.00664% Intralan Bordeaux EL* 
0.01892% C.I. Acid Blue 171 
0.09220% C.I. Acid Black 132 
______________________________________ 
*Ciba Geigy Corp. 
The dye solution with CIBAFAST N.RTM. is metered in through the inlet side 
of the circulation pump of the Hisaka Jet Dyer over 80 minutes which is 
equivalent to 0.013% dye/minute based on the weight of the fabric. The 
rate of addition supplies 0.63% of the total dye solution per fabric 
revolution (machine cycle). 
The bath is then cooled to 160.degree. F. (71.1.degree. C.), a sample is 
taken to confirm that the desired color (shade) was achieved. The fabric 
is then rinsed and dried in the conventional manner. 
Inspection showed that the fabric had commercially acceptable visual 
levelness from side to side and had commercially acceptable uniformity. 
The dyed/dried fabric is subsequently napped and sheared in the 
conventional manner to produce a finished fabric suitable for use as 
automotive headliner cloth. The finished fabric is commercially acceptable 
as regards uniformity and side to side color levelness. 
EXAMPLE 17 
A warp knit fabric of 40 denier, 2 dpf, trilobal bright nylon 66 yarn is 
used in this example to illustrate beam dying in accordance with the 
invention. Approximately 20 yards (950 grams) of 17 inch wide fabric to be 
dyed are wound firmly and smoothly around a 4 in. diameter, 18 inch-long 
dyeing beam, which has already been covered with 3 layers of cheese cloth. 
The fabric is wound with the face of the fabric outward and is clamped at 
both ends of the beam. The tube and wound fabric are secured in a 
laboratory dyer built by Burlington Engineering Company. The fabric is 
scoured conventionally at 185.degree. F. (85.degree. C.) for 20 min. using 
0.5 grams per liter MERPOL LFH.RTM. in 38 liters of water. The fabric is 
overflow rinsed to remove all scouring agents and then the bath is 
dropped. 
The dyeing bath is then set with 38 liters of water at a 40:1 liquor ratio 
(weight of bath to weight of fabric) at 80.degree. F. (26.7.degree. C.) 
and then the pH is adjusted to 5.0 with monosodium phosphate (MSP) and 
phosphoric acid. The bath is pumped at full pump pressure through the 
dyeing beam and fabric. The temperature of the dyeing bath is raised 
rapidly by 7.degree. F. (3.9.degree. C.) per minute to 180.degree. F. 
(82.2.degree. C.). 
Separately 9.5 grams of Anthraquinone Milling Blue BL (C.I. Acid Blue 122) 
dye is dissolved in 3800 ml of water to form a dye concentrate. Using the 
precision metering pump of Example 1, the separately prepared dye solution 
is metered into the expansion tank of the beam dyer at the rate of 95 
ml/min for 40 minutes. Under these conditions, there is almost no visible 
build up of dye in the dyeing bath during the period of dye addition. The 
dyeing bath is cooled and drained. The fabric is overflow rinsed, removed 
from the dyeing machines, then air dried. 
The result obtained is a level blue dyeing of the nylon warp knit and a 
colorless dyeing bath.