U.S. patent application number 17/504942 was filed with the patent office on 2022-04-21 for dye range, improved dye range processes, and yarns and fabrics produced therefrom.
The applicant listed for this patent is CleanKore, LLC. Invention is credited to Heath COLWELL, Darryl J. COSTIN, JR., Darryl J. COSTIN, SR., Ken KISER, Alpesh PATEL, Dennis SCHEER.
Application Number | 20220120033 17/504942 |
Document ID | / |
Family ID | 1000006064118 |
Filed Date | 2022-04-21 |
United States Patent
Application |
20220120033 |
Kind Code |
A1 |
COLWELL; Heath ; et
al. |
April 21, 2022 |
DYE RANGE, IMPROVED DYE RANGE PROCESSES, AND YARNS AND FABRICS
PRODUCED THEREFROM
Abstract
The present invention relates to yarn dyeing, such as denim
dyeing. A process provides a dyed yarn having reduced dye
penetration and a white core at lower cost. The improved process
for yarn dyeing is referred to herein as the CleanKore technology.
The CleanKore technology improves one or more steps in dye ranges
to achieve dyeing of the yarn while retaining a white core at the
center of the yarn. When viewing a cross-section of a yarn, the
peripheral portion is dyed while the center remains white (not
dyed). The CleanKore technology modifies the scouring stage (or
phase), the scour rinsing stage, the dyeing stage, and/or the dye
rinsing phase of existing dye ranges. The modifications may be
applied individually or any combinations thereof to the existing
dye range.
Inventors: |
COLWELL; Heath; (Sheffield
Lake, OH) ; COSTIN, JR.; Darryl J.; (Bay Village,
OH) ; KISER; Ken; (Richmond, KY) ; PATEL;
Alpesh; (Ahmedabad, IN) ; COSTIN, SR.; Darryl J.;
(Avon Lake, OH) ; SCHEER; Dennis; (Greensboro,
NC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CleanKore, LLC |
Westlake |
OH |
US |
|
|
Family ID: |
1000006064118 |
Appl. No.: |
17/504942 |
Filed: |
October 19, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
63094108 |
Oct 20, 2020 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D03D 15/217 20210101;
D10B 2201/02 20130101; D06P 1/30 20130101; D06P 5/2066 20130101;
D03D 15/54 20210101; D06P 5/02 20130101; D06P 1/228 20130101; D06P
1/0032 20130101; D06C 23/02 20130101 |
International
Class: |
D06P 1/00 20060101
D06P001/00; D06C 23/02 20060101 D06C023/02; D03D 15/217 20060101
D03D015/217; D03D 15/54 20060101 D03D015/54; D06P 1/22 20060101
D06P001/22; D06P 1/30 20060101 D06P001/30; D06P 5/20 20060101
D06P005/20; D06P 5/02 20060101 D06P005/02 |
Claims
1. A method for dying yarns, comprising the steps of a. providing a
dye range comprising a scouring stage, a scour rinsing stage, a
dyeing stage, an oxidation stage, and a dye rinsing stage; and b.
modifying the dye range by three or more of the following steps to
provide a modified dye range: i. reducing an immersion time of the
single scouring vat in a range of about 4 total seconds to about 20
total seconds, ii. maintaining a temperature in the single scouring
vat at approximately equal to a temperature of the highest tap
water temperature for the location of the dye range, iii.
maintaining a caustic concentration of about 0.5 to about 40 g/L in
the scouring stage, iv. maintaining a pH range of about 11 to about
12.2 in the scouring stage, v. reducing a wetting agent in the
scouring state to about 0.7 to about 4 g/L, vi. reducing the scour
rinsing stage to a single scour rinsing vat; vii. reducing an
immersion time in the scour rinsing vat to a range of about 4 total
seconds to about 20 total seconds, viii. optimizing water flow in
the dye rinsing stage(s) to maintain a pH range of about 7 to 11 in
the dye rinsing stage, ix. eliminating the scouring stage and/or
the scour rinsing stage, x. reducing dwell time of the yarns, xi.
maintaining a temperature of dyeing stage within 5.degree. C. of
the highest tap water temperature for the location of the dye
range, xii. adjusting an immersion time of the yarn in the dyeing
stage to about 7 to about 18 seconds, xiii. removing or reducing
any wetting agents in the dyeing stage, xiv. maintaining a dye
immersion time to oxidation time ratio of about 1:6 to about 1:18,
and xv. providing a first dye rinsing vat and a second dye rising
vat in the dye rinsing stage, the first dye rinsing vat has an
immersion time of about 4 to about 12 seconds, and the second dye
rising vat has an immersion time of about 7 to about 22
seconds.
2. The method of claim 1, wherein steps i, vii, x, xii, xiv, and
xiv are accomplished by changing the threading path of the yarns
through rollers in the dye range and/or removing some of the
rollers.
3. The method of claim 1, wherein step i has an immersion time of
about 5 seconds to about 13 seconds.
4. The method of claim 1, wherein the mV of dying stage is
maintained in a range between -675 mV and -750 mV.
5. The method of claim 1, wherein step x is accomplished by
threading the yarns to provide the shortest path between the
scouring step and the scour rinsing step, and between the scour
rinsing step and the dyeing step.
6. The method of claim 1, wherein the caustic concentration in the
scouring stage is maintained in a range of about 0.5 g/L to 8
g/L.
7. The method of claim 1, wherein the dyeing stage uses indigo dye
or sulphur dye.
8. The method of claim 7, wherein the sulphur dye is heated to a
temperature range of 70.degree. C. to 80.degree. C.
9-13. (canceled)
14. A method for modifying a dye range, said dye range includes a
sulphur dye and scouring combination stage, a sulphur scour
combination rinsing stage, indigo dyeing stage, oxidation stage,
and an indigo dye rinsing stage, the method comprises the following
steps: i. reduce an immersion time of the sulphur scour combination
tank to range of about 4 seconds to about 15 seconds ii. reducing a
wetting agent in the sulphur scour combination stage in a range of
about 0.7 g/L to about 4 g/L, iii. adjusting an immersion time of
the yarn in the indigo dyeing immersion stage to range of about 7
to about 18 seconds, iv. removing wetting agents in the indigo
dyeing stage, v. optimizing water flow in the indigo dye rinsing
stage to maintain a pH range of about 7 to about 11 in the dye
rinsing stage.
15. The method of claim 14, wherein the water flow to the sulphur
scour combination rinsing stage is maintain a pH in the range of
about 7 to about 11.
16. The method in claim 14, wherein the time ratio of dye immersion
and air oxidation is within a range from 1:7 to 1:15
17. The method of claim 14, where in the temperature of the sulphur
dye and scouring combination stage is maintained between 70.degree.
C. and 80.degree. C.
18. The method of claim 14, where in the sulphur scour combination
rinsing stage is not additionally heated beyond the tap water
temperature.
19. The method of claim 14, wherein yarns are threaded in the
shortest path between the sulphur dye and scouring combination
stage nip roller and the sulphur scour combination rinsing
stage.
20. The method of claim 14, wherein the water flow is such that the
pH of the indigo dye rinsing stage is maintain in a range between
9.5 and 10.2.
21. The method of claim 14, wherein the solution used in the indigo
dyeing stage is heated within about 5.degree. C. of the highest tap
water temperature experienced at a respective dye range in a
typical year.
22. A method of dyeing a yarn having a cleaned periphery and an
uncleaned center core, comprising the steps of: a. providing a
cotton yarn having impurities distributed throughout the yarn; b.
passing the yarn through a scour bath so that only some of the
impurities are removed from the yarn, the remaining impurities
being situated within the central area of the yarn; c. passing the
scoured yarn through at least one dye bath so that the dye
infiltrates the scoured portion of the yarn; d. fixing the dye to
the yarn.
23. The method of claim 22, including the steps of passing the yarn
through a plurality of dye baths and/or through a plurality of
rinse baths and/or through a plurality of oxidizing stages.
24. The method of claim 22, including the step of passing the yarns
through at least one scour bath, the at least one scour bath
including dye.
25. The method of claim 22, including the steps of: a. providing a
dye bath that contains indigo dye stuffs; b. dyeing the yarn with
the indigo dye; and c. oxidizing the dyed yarn after it exits the
dye bath.
26-30. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS AND CLAIM TO PRIORITY
[0001] This application is related to and claims the priority of
U.S. Provisional Patent Application No. 63/094,108, filed Oct. 20,
2020, which is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention generally relates to fabric dyeing,
such as denim dyeing. In particular, a process is provided which to
provide a dyed yarn having reduced dye penetration and a white core
at lower cost. The process involves modification of existing dye
ranges in order to more efficiently and in an environmentally
improved method produce dyed fabrics, particularly those that are
indigo and/or sulphur dyed.
BACKGROUND OF THE INVENTION
[0003] For over a century, the world has adopted many different
styles in fashion. One style quite common throughout that time has
been a fabric generally known as denim. Denim consists of warp and
weft yarns. Warp yarns are understood to be the yarns that run the
length of the fabric yardage, whereas the weft yarns run
perpendicular, from side to side. Traditional denim typically has
dyed warp yarns with contrasting undyed or "white" weft yarns.
[0004] Denim is a woven fabric typically involving a majority
cotton content. These cotton fibers are often wrapped with or
around synthetic fibers. The warp yarns are traditionally dyed, and
the weft yarns typically remain their natural (white or mostly
white) color. The weaving process leaves the dyed warp yarns
predominantly visible on the face of the material and the weft
yarns predominantly visible on the reverse or backside.
[0005] Denim has many appreciable qualities to it. The "hand" or
touch of the material, is largely determined by the traits of the
yarn and weaving technique, is seen as desirable for numerous
reasons, as are the different colors available. By a wide margin,
various shades of blue make up the most common of colors for denim.
Typically, indigo dyes are used, at least in part, to make these
shades of blue. Oftentimes sulfur dye or dyes complement the shades
of blue to produce color variations otherwise difficult or
impossible to create with indigo alone. At the time of this
application, nearly all warp yarns are dyed on machines or lines
known as dye ranges. Dye ranges generally include rollers to thread
the yarns as it proceeds through several stages in the course of
dyeing the yarn. The stages include a scouring stage to clean the
yarns, a scour rinsing stage to remove the chemicals used in the
scouring stage, a dyeing stage to dye the yarns, an oxidation stage
to oxidize the dye applied to the yarns, and a dye rinsing stage to
remove excess dye on the yarns.
[0006] Traditional scouring techniques result in yarns that are
excessively cleaned. Excessively cleaned yarns cause too much
material, such as oils and waxes, to be removed from the center or
core area of the yarn. The removal of these materials makes it more
likely the dyes will be exposed to more hydrophilic fibers of the
cotton which results in dye penetration and fixing within the core
(center) area of the yarns 106.
[0007] Dye ranges are designed by the manufacturer of the dye
range. Each denim mill can customize which tanks its dye range has,
which tanks have heaters, which are connected together etc., as
well as the addition of drying cans where they deem appropriate.
The design of the individual stages on a dye range, however, is
left to the manufacturer's discretion. Without exception, the
inventors have not experienced a mill with customized immersion
times achieved through the rethreading of the yarns in anything but
the conventional, prescribed threading.
[0008] These conventional practices have profound implications
regarding the time the yarns spend immersed in scouring stages (or
phases), dyeing stages, rinsing stages, etc. These conventional
practices consume excess amounts of chemicals and heat and cause
environmental issues. Clearly improvements may be made to dye range
operations in order to provide a more useful dyed yarn that
minimizes costs and environmental issues.
SUMMARY OF THE INVENTION
[0009] The present invention provides an improved process for yarn
dyeing, referred to herein as the CleanKore technology. The present
invention (CleanKore technology) identifies, improves upon, and
modifies one or more steps in existing conventional dye ranges to
achieve dyeing of the yarn while retaining a white core at the
center of the yarn. When viewing at a cross-section of a yarn, the
peripheral portion of the yarn is dyed, and the center of the
cross-section remains white (not dyed). Preferably, implementing
the disclosed invention, results in the impurities remaining in
about 50% to about 85% of the center core of the threads, so that
only the outer scoured area is easily dyed. Dying the periphery and
allowing the core to remain white is advantageous, particularly
when the resulting fabric is lased with a laser in order to provide
a desired image on the fabric. The CleanKore technology modifies
the scouring stage (or phase), the scour rinsing stage, the dyeing
stage, and/or the dye rinsing phase of existing dye ranges. The
modifications may be applied individually or any combinations
thereof to the existing dye range.
[0010] In the scouring stage, the CleanKore technology provides one
or more of the following: [0011] i. an immersion time of about 4 to
about 20 seconds, [0012] ii. an operating temperature approximately
equal to a temperature of the highest tap water room temperature
for the location of the dye range, [0013] iii. a caustic soda
("caustic") concentration of about 1 to about 40 g/L, [0014] iv. a
pH of about 11 to about 12.2, and [0015] v. a wetting agent at a
concentration of about 1 to about 4 g/L.
[0016] In the scour rinsing stage, the CleanKore technology
provides one or more of the following: [0017] i. an immersion time
in the scour rinsing vat to about 4 to about 20 seconds, and [0018]
ii. a pH of less than about 10.
[0019] In the dyeing stage, the CleanKore technology provides one
or more of the following: [0020] i. a temperature within 5.degree.
C. of the highest room temperature for the location of the dye
range, and/or [0021] ii. an immersion time of the yarn in the
dyeing stage to about 7 to about 18 seconds, and [0022] iii. little
to no wetting agent.
[0023] In the dye rinsing stage, the CleanKore technology provides
one or more of the following: [0024] i. two rinsing vats configured
for an immersion time of about 4 to about 12 seconds in the first
rinsing vat, and an immersion time of about 7 to about 22 seconds
in the second rinsing vat, and [0025] ii. a pH of about 7 to about
11.
[0026] Additionally, the oxidation stage is configured so that the
ratio of the dye immersion time (from the dyeing stage) to the time
in the oxidation stage is about 1:6 to about 1:18.
[0027] Further areas of applicability, including apparatus,
devices, kits, processes, and the like which constitute part of the
invention, of the present invention will become apparent from the
detailed description provided hereinafter. It should be understood
that the detailed description and specific examples, while
indicating the preferred embodiment of the invention, are intended
for purposes of illustration only and are not intended to limit the
scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The accompanying drawings are incorporated in and constitute
a part of the specification. The drawings, together with the
general description given above and the detailed description of the
exemplary embodiments and methods given below, serve to explain the
principles of the invention. The objects and advantages of the
invention will become apparent from a study of the following
specification when viewed in light of the accompanying drawings, in
which like elements are given the same or analogous reference
numerals and wherein:
[0029] FIG. 1 is a diagram showing a dye range;
[0030] FIG. 2 is a photograph showing an empty vat;
[0031] FIG. 3 is a photograph showing the cross-section of a yarn
dyed using the CleanKore technology;
[0032] FIG. 4 is an image showing the software-edited portion of
the yarn shown in FIG. 3
[0033] FIG. 5 is an image showing the software-edited white core of
the yarn shown in FIG. 4
[0034] FIG. 6 is a photograph showing a typical stone washed
garment; and
[0035] FIG. 7 is an enlargement of a dye vat and oxidation stage of
FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] The inventors have identified several inventive steps as
well as changes to the existing dyeing process. The changes greatly
influence the levels of dye penetration, dye fastness, and white
core retention. These changes are the subject of the present
invention and referred to herein as the CleanKore technology. These
steps are described below and may be applied individually or any
combinations thereof to an existing dye range to provide chemical,
energy and cost savings. The steps allow for dyeing of the outer
portion of a yarn, while retaining a white core at the center of
the yarn. CleanKore technology may be used with sulfur dye or
indigo dye, with indigo dye being preferred.
[0037] An example of the workflow on a dye range 100 is shown in
FIG. 1. Dye ranges include many large containers called vats 102
(or boxes or tanks). These vats 102 are commonly filled with
thousands of liters of chemicals, water, and/or dye. The vats serve
different purposes and therefore have chemicals that differ from
other vats. As yarns 106 progress through the dye range 100, they
pass over rollers 104 (nip rollers 104a and regular rollers 104b
are referred herein collectively as rollers 104) that range from a
few inches to a couple of feet in diameter. These rollers 104 are
found within the vats 102 as well as outside of the vats 102. Nip
rollers 104a pull the yarns through the range 100 while also
squeezing moisture from the yarns 106; and regular rollers 104b are
simply rollers that the yarns 106 pass over. Nip rollers 104a will
be addressed in greater detail further on. The yarns 106 pass over
(or under) the various rollers 104 as they progress through the
range 100.
[0038] The dye range 100 first scours the yarns 106 to wash them of
impurities in scouring vats 102a. The scouring process prepares the
yarns 106 for dyeing. After scouring, the yarns 106 are washed in a
scour wash (rinse) vat 102d to remove chemicals used in the scour
vat 102a from the yarns 106. The yarns 106 are then dyed in a
plurality of dye vats 102b. After each dye vat 102b, the yarns 106
are exposed to air by passing through a plurality of regular
rollers 104b above the dye vats 102b to allow the dye to oxidize.
After dyeing, the yarns 106 are passed through rinsing vats 102c to
remove excess dyes on the yarns 106. Once rinsed, the yarns 106 are
dried.
[0039] The dye range 100 begins with the scouring process. The
scouring process traditionally involves one or more tanks or vats
102a within which yarns 106 are passed over a series of rollers
104. FIG. 2 shows an example of an empty vat 102a with yarns
threaded over and under cooperating sets of regular rollers 104b.
These vats 102a are filled with water and chemicals, such as
caustic soda, chelate agents, and wetting agents, such as
Primasol.TM. from Archroma, for example. These vats 102a are
composed of a series of regular rollers 104b that cause the yarns
106 to be immersed in the chemicals as the yarns 106 move through
the range 100.
[0040] With respect to scour chemistry in the vats 102a, caustic
soda or sodium hydroxide is one of the active ingredients in the
scour vat 102a. It breaks down the naturally occurring oils and
waxes in the yarns 106 as it encounters them. Water is the overall
medium within which yarns 106 pass and serves to carry away the
oils and waxes that have been broken down and removed from the
yarns 106 by the caustic. Wetting agents act as surfactants,
reducing the surface tension of the liquids in the vats 102a which
causes the caustic soda solution to much more rapidly penetrate the
yarns 106. The chelating agents normalize the metal ions in the
water and trap the isolated fats and waxes from cotton. Isolating
the fats and waxes from the cotton that makes up yarns 106 helps to
protect the cotton yarn 106 from the re-deposition of
impurities.
[0041] When practicing CleanKore technology, it is desirable to
reduce the number of scouring vats 102a to a single container.
Next, the inventors change the threading path through the rollers
104 to reduce the amount of time each yarn 106 spends in the single
scour vat 102a. Immersion time during scouring is reduced from a
conventional standard of around 21 seconds to a range of about 4 to
about 20 seconds with the preferred immersion time being about 10
seconds.
[0042] The inventors also change the conditions and chemistry found
in the respective scour vat 102a. Typical chemicals in the scour
vat 102a include wetting agents, caustic soda, chelating agents,
and/or sequestrants. Several mills heat their scour boxes 102a to
50.degree. C. or higher to further penetrate the core of the yarn
106 and fully clean the yarn 106. With CleanKore technology, energy
savings are captured, and the size and quality of the core is
improved by operating the scour vats 102a at room temperature or
the highest tap water temperature in climates that experience
extreme temperature swings. For example, if a mill experiences a
tap water temperature of 8.degree. C. during the winter months and
a tap water temperature of 25.degree. C. during the summer months,
for the sake of consistency, the CleanKore technology operates the
scour vat 102a continuously at 25.degree. C. all year round so that
scouring potential is consistent from month to month. CleanKore
determines the appropriate scour potential to limit dye penetration
into the core by controlling the temperature, scour chemistry, the
concentration of that chemistry, immersion time in that chemistry,
nip pressure, and/or dwell time during the scouring stage. These
factors can result in mills with a more consistent climate and
consistent tap water room temperatures, within approximately
10.degree. C. Using CleanKore technology requires little to no
heating for the scour vat 102a.
[0043] In addition, the scour chemistry is also changed. Caustic
soda is most commonly used in two forms; a flake form, which is a
"100%" pure dried caustic flakes (100% flakes), and 50% prediluted
caustic aqueous solution. Of these two forms, 100% flake is the
most encountered form. Conventional scour chemistries contain 12
g/L up to 90 g/L of 100% flakes in the scour chemistry. A
concentration in the scour vat 102a in a range of about 1 to about
40 g/L of 100% flakes with the preferred concentration of about 3
g/L of 100% flakes is preferred with the invention. The 50%
prediluted solution may also be used but should be used at the same
caustic concentration as the flakes in the scour vat 102a. Typical
prior art ranges 100 run their scour vats 102a with a pH of 12-13.
While pH is no measure of true alkalinity, pH is a valid indicator
of yarn scouring levels. The pH of the CleanKore scour vat 102a
ranges from about 11 to about 12.2 with a preferred pH of about
11.8 to about 12.1.
[0044] The wetting agent (surfactant) dosing encountered in the
prior art scour vats 102a has been as high as 12 g/L. To further
protect the white core from excess scouring as well as reduce
chemical usage, the CleanKore technology uses a wetting agent at a
range of about 1 g/L to about 4 g/L in the scour vat 102a, with a
preferred concentration of about 2 g/L.
[0045] After having passed through the scour vat 102a, the yarns
106 are then rinsed in water. We refer to this step as the scour
rinsing stage, which occurs in one or more scour rinse vats 102d.
The scour rinse is desirable and serves to remove the caustic and
contaminants before the yarns 106 are passed through the dye vats
102b containing dye chemistries. Oftentimes the scour rinse can
occur across the span of up to three vats 102d, with the immersion
in each vat 102d typically being 20 to 22 seconds. One embodiment
of this invention is to reduce the scour rinse vats 102d to a
single container and reduce the scour rinse immersion time to a
range of about 4 to about 20 seconds, with the preferred rinse
immersion time being about 7 to about 12 seconds. Preferably, the
water in the scour rinse vat is room temperature and is not
heated.
[0046] One consistent critical liability with every scour rinse vat
102d encountered is that the water flow to each of the vats 102d
has not been optimized. Optimization of water flow rates involves
adjusting the water flow rate, up or down, in order to maintain
sufficient cleansing of the yarn 106 and removing the chemicals
introduced in the scouring process, as well as the impurities from
the water (and consequently the yarn) that were broken loose in the
scouring stage without the flow being excessive. Optimization is
realized when the water flow is such that the pH of each respective
sour rinsing vat 102d does not rise above 9.9. The contamination of
the scour rinse(s) results in changes in dyeing until the boxes are
in equilibrium. The inventors refer to equilibrium as the point at
which the rinse box(es) 102d, which start as water with a pH of
approximately 7, reaches and maintains a respective highest
contamination rate per the recommended parameters of pH<10 from
the yarn and scour chemistry introduced from the previous vats
102d. Insufficient freshwater flow to the scour rinse tanks 102d
results in scouring chemistry concentrations that are high enough
that the scour rinse unintentionally continues to further the
scouring of the yarns 106. Continued scouring in the rinse vats
102d of the yarns 106 is not desirable. Optimizing the water flow
in the scour rinse vat 102d is important relative to white core
retention. An optimized flow rate assures a lower contamination
point for equilibrium without excessive water usage. This
optimization results in less scour chemistry contaminates in the
scour rinse vat 102d, which would otherwise continue to affect the
yarns 106 during the rinsing stage. Minimizing the amount of
scouring beyond that which is needed to scour the outside of the
yarn 106 while keeping the core un-scoured and thus limiting dye
penetration is important to provide a more useful dyed yarn, and
ultimately fabric.
[0047] One inventive step is to reduce the dwell time of the yarn,
which is the time spent between immersion in one tank and immersion
in the next. In this specific context, addressing the dwell time
between the scour vat 102a and the scour rinse vat 102d. Reducing
this dwell time offers better control of purposeful scouring which
continues to improve the effect of scouring the outside perimeter
of the yarn 106 while leaving the core of the yarn 106 with its
original contaminants intact. The reduction in dwell time occurs
when the shortest path from the scour vat 102a to the scour rinse
vat 102d is used. Oftentimes, the yarns 106 are threaded through a
series of rollers 104 between scour vats 102a, between scour vats
102a and scour rinse vats 102d, and lastly, between scour rinse
vats 102d and the first dye vat 102b. The invention threads the
yarns 106 from the nip roller 104a of the previous step along the
shortest path to the next vat, with the obvious exception being the
oxidation stages between dye vats (102b). This rethreading may
bypass certain roller(s) 104 used by the manufacturer-supplied
process.
[0048] In some regions of the world, the scarcity of water makes it
a more precious resource than in others. For this reason,
alternative CleanKore variations have been experimented with to
improve water savings, while still retaining much-improved core
characteristics. We have developed two such solutions: 1) skip the
scouring phase; and/or 2) skip the scour rinse.
[0049] Another embodiment is where the scour tank 102a is processed
following CleanKore guidelines, but rather than processing the
yarns 106 through a rinse vat 102d, the yarns 106 are expeditiously
pathed into the dye vats 102b directly from the scour vats 102a. In
this case, within the dye vats 102b, there is an additional
decrease in caustic feed to counter the addition of caustic from
the scour tank. The decrease in the caustic feed of the dye vats
102b is the amount normally used for dye stuff reduction, per
chemical distributor guidelines, minus the amount from the yarns
106 that come directly from the scour vat 102a.
[0050] As the yarns 106 pass from the immersion stage of any given
vat 102 on a dye range 100, they invariably pass between what is
known as a nip roller 104a. Referring to FIGS. 1 and 6, a nip
roller 104a includes two rollers that turn while being pressed
together with a force. Typically, one nip roller 104a is driven
while the other spins freely, and air cylinders usually press one
roller towards the other. The pressure from the air cylinders
creates a squeezing action from the medium that passes between the
rollers. In the context of dye range 100, the medium passing
between the nip rollers 104a is the yarns 106 or ropes composed of
yarns 106. The nip roller 104a pressure is intended to squeeze out
whatever liquid the yarns 106 was most recently immersed in from
each vat 102. The nip rollers 102a from the scour vat 102a squeeze
much of the scour chemistry out of the yarn 106 and allows the
squeezed scour to drip back into the scour vat 102a. The nip roller
104a function is important in both better controlling the amount of
time the yarns 106 are exposed to the scour chemistry and to
reducing the contamination rate of the successive vats 102. For
this reason, one embodiment of the invention is to increase the nip
pressures across the line from the traditional 40-60 PSI to about
60 to about 100 PSI (pounds per square inch), with preferred
pressure being about 100 PSI. Sometimes, the denim mills have
pressure limitations, where the pressure should be increased as
close to the desired range as possible.
[0051] Dye vats 102b are large tanks containing a dye solution (or
dye chemistry), within which yarns 106 pass over a series of
rollers 104. The size of the dye vats 102b is typically over 250
gallons each, with some as large as 700 gallons. These large vats
102b are quite often heated to temperatures around 60.degree. C. in
an attempt for the dye to deeply penetrate the yarns 106, with the
incorrect understanding that this is the only method to achieve a
consistent or dark shade. Tremendous energy savings and
much-improved white core retention is achieved with the CleanKore
dyeing technology which requires no purposeful heating of the dye
vats 102b, other than to maintain a constant or near-constant
temperature throughout the year for the local climate. That is to
say, in order for the dyeing to be consistent throughout the year,
the solution in the dye vats 102b should be heated within about
5.degree. C. of the highest tap water temperature experienced at
each respective dye range in the hottest season.
[0052] The yarn path over or under regular rollers 104b in dye vat
102b typically immerses the yarns 106 up to 24 seconds in dye
chemistry. One embodiment of the invention is to change the yarn
path of the yarns 106 between the rollers (or removing rollers, or
simply designing the range with fewer rollers) to adjust the
immersion time to a range of about 7 to about 18 seconds, with the
preferred immersion time being about 11 seconds for each dye vat
102a at a given speed. Among the factors that determine the dye
immersion time are yarn diameter, yarn twist, tension maintained on
the dye range, target shade, and dye vat chemistry. For example,
lower yarn twist, lower tension, lighter target shade, or
particularly high pH or mV in a dye tank 102b justify a lower
period in (immersed) the dye vat 102b. The immersion time may
deviate within 1-3 seconds as each parameter is subjected to range
configuration regarding roller placement and range speeds
available.
[0053] Conventionally, dye vats 102b have chemistry resulting in a
pH in a range of 11.5-12.5. The CleanKore chemistry has a pH range
of 11.5 to 12.5, but the preferred dye vat 102b pH range is about
11.6 to about 11.8. The conventional dye tank mV range is -700 to
-775, whereas the CleanKore preferred mV range is about -675 to
about -775, and the ideal mV in the indigo dye tanks is about
-715.
[0054] After each dye immersion vat 102b, the yarns 106 are
processed through a nip roller 104a and then enter a dye oxidation
stage. It is during the dye oxidation stage that the yarns 106 are
exposed to air through a series of regular rollers 104b. Sulfur and
indigo dyes are not water-soluble. During the immersion stage, the
dyes are reduced to a soluble state through the removal of oxygen.
Once the yarns exit the immersion stage 102b and begin the exposure
to oxygen, the dye returns to an insoluble state, effectively
bonding the dye to the yarns 106.
[0055] When the yarns 106 are removed from the dye vat 102b and
exposed to oxygen during the oxidation stage, the dye on the
outside of the yarns 106 experiences oxidation more readily than
the inner portions of the yarn 106. "Inner portions" are understood
to mean towards the center of the yarn when the yarn cross-section
is viewed, such as under a microscope. It is for this reason the
inventors have come to understand that there is merit in
optimization of the oxidation time rather than maximization of the
oxidation time. The thought is that rather than increasing the
fastness of the dye on the yarn perimeter, extended oxidation
disproportionately and undesirably increases the oxidation and
fixing of indigo to the inner portions of the yarns 106.
[0056] One embodiment is to achieve acceptably compromised dye
fastness. The dyeing process adds color to the yarns 106, but the
majority of the garment finishing involves the construction of the
fabric, and then chemical and physical attempts to remove the same
dye, to varying extents. Fastness is a measure of how well the dye
is "fixed" or experienced oxidation on yarns clean enough for
bonding between dye and yarn 106. One important feature of this
invention is the practice of intentionally and partially
compromising the yarn/dye bond such that the initial color loss
from industrial washings require less energy, but still retain
enough yarn/dye bond integrity that the yarn 106 or eventual
garment retains sufficient color while being processed with the
consumer-grade washing machine cycles.
[0057] The whole purpose of the dye range 100 is to add dye to the
yarns 106. Indigo and sulfur dyes are by far the most common dyes
used on denim dye ranges 100, and the amount of dye added to the
yarn 106 is measured by weight and is given as a percentage of the
overall weight of the yarn. This is abbreviated to "% add-on weight
of yarns." With conventional dyeing techniques, the mindset has
been to pile as much dye onto a yarn 106 as possible in order to
achieve a darker color. Because CleanKore technology more
consistently dyes the outer perimeter of the yarn 106, there is
often a % add-on weight of yarn reduction between 5% and 30% lower
than the typical range add-on being 15% less than a comparable
product processed conventionally while achieving a similar yarn dye
shade. The results in a 15% reduced dye chemistry consumption and
therefore a 15% reduced indigo feed rate is realized in most
typical dyeing scenarios. Reducing the consumption of the dye
chemistry necessarily involves a reduction in the polluting
chemistries associated with dye reduction, such as caustic soda, as
well as hydro (sodium hydrosulfite), or competing chemical
technologies used in the reduction of the dyes.
[0058] The conventional mindset of dye-to-the-core often involves
the use of wetting agents in the dye chemistry. As with the excess
caustic in the scour, this improves possibility (and probability)
that the dye chemistry penetrates farther towards the core and more
importantly, the dye fixes to the core area of the yarns.
Specifically for this reason, CleanKore technology works best when
wetting agents are completely removed from the dye chemistry.
Removal of the wetting agent from the dye chemistry encourages a
nice dye ring on the perimeter of the yarn where a dark color can
be achieved without core penetration. Practicing CleanKore
technology while retaining the wetting agent, may still result in
improvement in core size relative to the yarn cross-section, but it
should be anticipated that lessening or removing the wetting agents
further reduces the dye penetration into the core.
[0059] The chemistry in the dye vats 102b exists for the purpose of
converting the insoluble indigo dye to a soluble dye. When yarns
106 are passed through the vats 102b with exclusively insoluble
dye, for the most part, the color fades out of the yarns 106 with
very little washing or abrasion as it is merely "on" the yarns
rather than mixed within and fasted to the fibers. Soluble dyes
penetrate the fibers of the yarn 106, whether on the surface or in
the core. In order to "fix" the dye to the yarn 106, or make it
more difficult to remove, the dye must be returned to its original
insoluble state after it has penetrated the yarn fibers. This stage
is known as oxidation, or "sky" time. It is often referred to as
"sky" time because upon exiting each of the dye vats 102b, the
yarns 106 pass through a nip roller 104a and then proceed through a
series of regular rollers 104b that are typically, but not
exclusively, high above the dye range in the "sky" of the building.
Oftentimes, these rollers 104b are spaced vertically and reach
heights as high as 30-40 feet above the top of the dye vats 102b.
The purpose of the oxidation is simply to expose the dye chemistry
to the oxygen in the air, which converts the soluble dye to its
insoluble state, thereby, fixing the dye to the fibers of the yarn
106. The amount of time in the dye vat 102b is recorded and then
compared to the amount of time spent in the oxidation cycle that
follows a dye vat 102b. The typical immersion time is 20 seconds in
a dye vat 102b, and a typical oxidation phase is approximately 100
seconds. This results in dye immersion to oxidation time ratio of
1:5. Where possible, CleanKore technology involves lengthening the
oxidation phase and shortening the dye immersion stage. CleanKore
Technology benefits the most within a dye immersion time to
oxidation time ratio of about 1:6 to about 1:18, preferably
1:10.
[0060] After the last dye cycle of dye immersion and oxidation
(with the nip roller in between), the yarns 106 proceed to a dye
rinse stage which typically occurs in one or more dye rinse vats
102c. This dye rinse stage rinses the yarns 106 of excess dye and
removes dye that has not fasted to the yarns 106 during the
oxidation phase. The number of dye rinse vats 102c at a given mill
on a given range may vary between one to three. Most mills have
more than one range and sometimes those ranges have different
configurations. Similar to the scour, scour rinse, and dye stages,
the immersion time in the dye rinse vats 102c for a conventional
process is around 20-22 seconds. The dye rinse vats 102c are often
400-750 gallons in size. Unfortunately, conventional operation,
without exception, involves a freshwater flow rate too low to be
effective in rinsing dye adequately. This results in dye rinse vats
102c that start with fresh water but, as the range continues to
operate, the contamination builds of dye. At equilibrium, the dye
rinse vats 102c effectively become a low-quality dye tank due to
the contaminants washed from the yarns 106 and not removed from the
rinse tank 102c. Instead of rinsing excess dye, the contaminated
dye rinse tanks 102c cause redeposition of excess dye on the yarns
106, which pollutes the core and lessens the integrity of the
fastness of the dyes that remain due to the lack of the oxidation
phase that proceeds the dye vats 102b. CleanKore technology solves
this problem. CleanKore technology dye rinse occurs with an
immersion time ranging from 4 to 22 seconds. With the
implementation of CleanKore technology, oftentimes the
configuration for optimized rinses is what is referred to as
"staggered rinses", frequently using two dye rinse vats 102c in
series. The first dye rinse in the first dye rinsing vat 102c is
referred to as a "quick rinse" and is relatively short. The first
dye rinse involves an immersion time of about 4 to about 12
seconds, preferably about 7 seconds. The second rinse in the second
dye rinse vat 102c involves an immersion time of about 7 to about
22 seconds, preferably about 14 seconds. Both of these vats 102c
have a flow rate similar to the flow rates of the scour rinse,
approximately 15 gallons per minute. The quick rinse with the
shorter immersion time removes approximately 50% of the targeted
dyes to be removed. Those are the dyes that are removed more
easily, with fewer tensioned passes through the regular rollers
104b. This reduced immersion time is the product of going over
fewer rollers, which reduces the contamination level of the first
rinse tank 102c to one that is more easily managed by the adjusted
freshwater flow rate. The second tank 102c needs only to contend
with the remaining dyes. With the increased number of tensioned
passes through regular rollers 104b, the targeted volume of
remaining dyes is stripped from the yarns. The lower contamination
rate that results from the more effective rinsing in the first dye
rinse vat 102c results in a second dye rinse vat 102c with a
tolerable contamination rate, offering no, or minimal dye
re-deposition and no negative impacts regarding the fastness of
previously fasted dyes.
[0061] Much like the scour rinse, the pH levels of the dye rinses
are monitored, which is unique to CleanKore practices. Successful
CleanKore technology dyeing can occur with a dye rinse pH in the
range of about 7 to about 11, but preferably below a pH of 10. The
dye rinse vats 102c are run at room or tap temperature, without
regard to the fluctuations of the tap or room temperature which
occur within regions. With effective rinsing, the temperature
fluctuations should have little impact on the variables associated
with this dye rinsing stage, and using the lowest available
temperature is preferred. Alternatively, a single dye rinse tank
can be used in circumstances of lighter shade, such as an about
3%-5% shade, or when needs for greater water conservation outweigh
dye quality, in which case the immersion time can be in a range of
about 7 to about 22 seconds, preferably about 10 seconds.
[0062] The mill, during and post-production, traditionally measures
the percentage add-on weight of dye on yarns in addition to
submitting the yarns to photo-spectrometer analysis. The percentage
add-on weight of dye on yarns 106 is calculated by weighing a
measure of yarns 106 both before and after dye. It is considered a
measure of the quality of shade. With the primary objective of
CleanKore technology being that less dye is used to cover a smaller
cross-section of yarns, the preferred method of measuring color
relies exclusively on analysis with a photo-spectrometer, or with a
modified understanding of percentage add-on weight of dye on
yarns.
[0063] If one were to visit thirty different mills and survey the
dye range specifications for each, it is highly unlikely that one
would find a dye range duplicated in every way at two different
locations. Changes in the number of vats 102, the roller
configurations within the vats 102, the addition or deletion of
vats 102 for various purposes, vat sizes, the number of yarns 106
or ropes, the line speeds, etc. are just a few examples of the
different changes one would expect from one location to another,
and often within a single mill amongst several ranges. It is for
this reason that one skilled in the art would recognize that the
practice of the disclosed embodiments may be in part or in whole of
what is disclosed. The decision of which embodiments are to be
determined for a particular range and the desired yarn dye output
according to the embodiments disclosed throughout this document may
certainly vary. However, several of the embodiments can be expected
to be implemented to achieve the extraordinary cost reduction and
sustainability improvements from CleanKore.
[0064] Without further description, it is believed that one of
ordinary skill in the art can, using the preceding description and
the following illustrative examples, make and utilize the articles
of the present invention and practice the claimed methods. It
should be understood that the invention is not to be limited to the
specific conditions or details described in the examples.
Example 1
[0065] Quite recently, while working with a mill in India on
product development a trial was proposed and executed. This
particular trial was to develop a CleanKore technology product that
could replace an existing denim jean style with improved wet and
dry processing characteristics. When beginning to implement
CleanKore technology, the first thing to be examined is the machine
sequence. Quite often there are steps that are options on a range
and therefore, by default, those options are implemented because it
seems that is how the machine "requires" the process to run when,
each box creates an opportunity that can be passed on.
[0066] With this embodiment in mind, inventors reviewed the range
sequence of the conventionally dyed yarns as shown below:
[0067] Box 1 was a combination of sulfur dye and scour;
[0068] Box 2 was a rinse;
[0069] Boxes 3, 4, 5, 6, 7, and 8 were indigo dye boxes;
[0070] Boxes 9 and 10 were both dye rinse boxes;
[0071] Box 11 was a neutralization;
[0072] The yarns were then dried, processed with sizing, and dried
again.
[0073] Applying the CleanKore technology, one of the first steps
was the omission of the number 10 rinse box. This embodiment of the
CleanKore invention is that an effective rinse does not need to be
repeated, which results in water savings.
[0074] The next logical step was to control the immersion time and
chemistry more accurately in each box.
[0075] With Box 1, a combination of sulphur and scour box, the
inventors reduced the immersion time from 16.4 seconds to 10.7
seconds. This reduction in immersion time exposed the yarns to
scouring and provided the sulfur bottom dye long enough to create a
bold perimeter of dye, without exposing the yarns so long that the
scour chemistry cleansed the core of the yarn which would
undesirably result in dye blended with the center or core portion
of the yarn. The period for immersion while practicing this
embodiment of the CleanKore invention for sulphur scour combination
box was 7-14 seconds, with the ideal period being from 8-11
seconds.
[0076] The chemistry in Box 1 consisted of sulfide, caustic,
sequestrant (the sequestrant softens the water (binds to metals)
and improves dyeing as a result), wetting agents, as well as the
sulfur dye and of course, water. The sulfide was reduced in Box 1
from 8 g/L to 4 g/L. The caustic that was added in addition to the
sulfur premix was reduced from 5 g/L to 2 g/L which resulted in a
reduction of the dye box pH value from 12.5 to 11.9. The
sequestrant was unchanged at 1 g/L, but the wetting agent was
reduced from 5 g/L to 2 g/L. The sulfur dye concentration for
CleanKore was left at 8 g/L as the conventional dye method. The
temperatures of sulphur dye stuffs, which tend to cause yarns to
open up and more readily receive dye and caustic, were reduced from
85.degree. C. to 70.degree. C. Temperature can be increased from
70.degree. C. but other factors such as time or amount of chemicals
may need to change accordingly to maintain the reduced dye
penetration.
[0077] Box 2 is the rinse stage to remove as much sulfur dye as
possible, so as to reduce the contamination in the indigo dye
boxes. The CleanKore technology included reducing the amount of
time the yarns spent immersed in the dye chemistry. This also
applies to time in rinse tanks. The removal of caustic via yarns
exposed to water while traversing over rollers under tension is a
relatively fast one. For this reason, the immersion time for Box #2
was reduced from 16.4 seconds to 10.7 seconds. The effective change
is that while the removal of caustic happens quickly, what
continues to happen is the yarns are exposed to the caustic
solution which scours the yarn. By reducing the immersion time, the
CleanKore technology effectively rinses the yarn while minimizing
the yarn exposure to caustic. The CleanKore technology practiced at
this rinse stage optimized the clean water flow to the rinse box so
that no less than twice the vat size is replacing contaminated
water with clean water per hour in order to reduce caustic levels
sufficiently, as reflected in pH value measurements. This water
flow requirements must be adjusted based on yarn diameters, yarn
counts, dye range speeds, or chemical concentrations in preceding
boxes, such that the pH values described herein are maintained.
[0078] Boxes 3, 4, 5, 6, 7, and 8 are the indigo dye boxes or vats.
Within these boxes, one feature of the CleanKore technology is the
purposeful absence of different chemicals. One such chemical is
wetting agents. Wetting agents are often used as a lubricant, to
increase the inward flow of dye towards the core of the yarn.
Practicing the CleanKore technology involves reducing the dye
penetration into the core. The wetting agent is an example of a
chemical ideally not added to dye stuffs and is reduced from
existing dye stuffs to a point the wetting agent is
ineffective.
[0079] The yarn immersion time is an important feature of the
CleanKore technology during the dyeing phase. This consideration is
because of the principle that excessive exposure of the yarn to the
dye chemistry unnecessarily exposes the yarn to the chemistry
involved with both scouring (caustic soda) and dyeing, which can,
with increased time, penetrate the yarn. Practicing this principle
is yet another feature of the CleanKore technology when the yarns
are immersed for the period of 7 to 15 seconds, with the preferred
or ideal period being between 10-13 seconds.
[0080] Yet another feature practiced in the dye vats is the
elimination of unnecessary heat. Heat is often conventionally used
to further the penetration into the yarns, with the idea that more
dye on the yarns will result in a darker color, even if the excess
dyes are not observable. This goal of furthering yarn penetration
with chemistry and dye is contrary to the CleanKore technology
objective, and consequently, excess heat is removed from the dye
tanks. Excess heat is referred to as the heat applied to a tank
that results in a temperature higher than the highest room
temperature of the climate within the region that a given mill or
dye range is located.
[0081] As a result of indigo penetrating less of the yarn center,
another feature of the CleanKore technology is to reduce the feed
rates of all or any of indigo dye, caustic, and hydro such that
each mill experiences a 10-15% chemical and dye savings while
processing with CleanKore technology.
[0082] For this particular trial, the next machine step was a
freshwater dye rinse. In addition to the previously mentioned
removal of an additional rinse, this step was considered similarly
to sulfur scour rinse. The rinse immersion time was reduced from
over 16 seconds to a range of 4-9 seconds, with an ideal rinse
immersion time of 7 seconds. Once again, another feature is that
the freshwater flow rate to this rinse box was maintained such that
the pH in the rinse tank did not exceed 9.9.
[0083] The last remaining step is an acetic acid cycle, which acts
to neutralize the alkaline condition from the caustic soda in the
dye, and fix the dye to the yarns. This is another cycle that
occurs faster than the conventional yarn immersion cycle.
Practicing the CleanKore technology principles, immersion time was
reduced from approximately 18 seconds to approximately 9 seconds to
reduce the redistribution of unfasted dyes, resulting in larger,
mostly undyed cores.
[0084] A smaller ring of dye around the perimeter of the yarn still
achieves the target shade of color without the undesired yarn
penetration. This decrease in yarn penetration with fasted dye
results in a more easily revealed core when processing garments
with dry or wet processing of garments. Significant benefits in
both the dry and wet processing are observed when the fabric from
garments is processed with CleanKore technology. Dry processing of
garments to remove color may be understood to be laser application,
hand sanding, rotary tool abrasion, or dry ozone, just to name a
few. Wet processing is typically understood to mean washing fabric
or garments in wet ozone, in conventional washing methods with
water and other various chemicals just to name a few methods.
[0085] This example was carried out with water, energy, and
chemical savings and resulted in a sulfur bottom indigo top product
with a larger, more distinct white core due to the practice of
several of the inventive embodiments.
Example 2
[0086] Yet another dye range provided a unique limitation in that
it lacked both a scour and a scour rinse box before yarns were
exposed to sulfur bottom dyeing. As the name implies, the sulfur
bottom dye is when the first color applied to the yarn is sulfur
with successive dye applications, typically indigo dyes, applied
afterward. The intent on this range was that yarns would be exposed
immediately to a vat containing both scour and dye chemistry. This
technique has been experienced before and it was the understanding
of the inventors this technique is a common approach with sulfur
dyes at this location and others. This mill was using a pre-reduced
sulfur dye which contains caustic, and then additional caustic and
wetting agents were added to act as scouring and penetrating
agents. Further increasing the potential of the scour was the heat
required for sulfur dyeing. This heat increasingly opened the
yarns, making the inroads of the caustic and wetting agents to
scour the core of the yarns. All of these things were undesirable
in the CleanKore technology. Therefore, in an attempt to limit the
effects these dye range limitations imposed the inventors made the
following changes: 1). eliminated the excess caustic that was added
to serve as an additional scouring agent such that the pH was
maintained between 11.8 and 12.5; 2). reduced the wetting agents
from 6 g/L to 1 g/L; 3) reduced the sodium sulfide (reducing agent)
levels to bring the mV readings up to -610 from -660; 4) reduced
the temperature of the dye vat from 85.degree. C. to around
75-80.degree. C., which was the lowest temperature recommended by
the distributor of the pre-reduced sulfur used; and 5) changed the
threading path to reduce the yarn dye immersion time from 22
seconds to 10.5 seconds by rethreading the yarn path. Modifying
ranges to best overcome dye range limitations such as those
disclosed above is yet another embodiment. The ranges provided for
various factors such as scour and dye immersion, as well as others,
are not broad for the sake of being broad, but rather a necessity
to accommodate both variations in dye ranges, as well as fully
encompass the potential of what could be considered an improvement
to conventional dyeing with all factors considered.
[0087] Depending on circumstances, rather than completely removing
the additional caustic from the dye vats, it may be reduced.
Circumstances that would call for such a measure could be
particularly waxy or oily yarns, or very high twist, such as 4.7 or
above. Putting optimum CleanKore technology in practice is
dependent on variables such as these and requires a complete
understanding of the invention as well as the other factors and
variables involved with dyeing as disclosed throughout this
specification.
[0088] The embodiments above with regard to both indigo and sulfur
dyeing similarly apply to sulfur only dyeing. Sulfur only dyeing
can involve more than 1 color, or more than 1 application of the
same color to achieve darker colors. Sulfur only dyeing refers
strictly to the types of dyes used, as the sulfur dye vats still
contain chemistry similar to the vats used in indigo dyeing.
CleanKore technology sulfur only dyed yarns will typically see a
reduction in heat from 85.degree. C. to around 75-80.degree. C., an
optimized immersion time from 7-22 seconds but preferably around 11
seconds, minimization or elimination of wetting agents to 0.7-1.5
g/L, less reducing agents, as well as reduced caustic in order to
further limit the core penetration of the sulfur dyes. These are
all features for sulfur only dyeing.
[0089] This example was carried out with water, energy, and
chemical savings The practicing of the disclosed embodiments
created sulfur bottom dyed yarns which had superior ring dyeing
effects, as viewed through a microscope, resulting in a larger core
with less dye penetration.
Example 3
[0090] Yet another trial conducted using CleanKore technology was
one that was entirely sulfur, known as sulfur black due to the lack
of other colors. Throughout the dye range 100, one skilled in the
art understands that there are rollers in place after any given
immersion process, even if each or any instance of a nip roller is
mentioned. Again, CleanKore technology was being used to improve
upon an existing process and correspondingly the product. The range
sequence is where some of the CleanKore technology changes began.
In the conventionally dyed product, the range yarn sequence was a
single scour and then proceeded through two oxidation stages before
going to a single sulfur tank. The yarns then went through an
oxidation phase before being passed over-drying cans. Drying cans
are typically metal drums (about 15-20 of them in the process)
having a diameter of about 0.5 m-1 m, which are heated to
relatively quickly remove the water from the yarns for storage
before weaving. In FIG. 1 the drying cans are shown at the end of
the dye range, which is common, but it is possible to have
additional drying cans throughout the range. After the drying cans,
the yarns were again skied or processed through an oxidation phase
before going through three water rinses stages. The yarns were then
rinsed in acetic acid to neutralize the remaining sulfur dyes and
reducing agents, and then were exposed to air for 2 minutes, before
another water rinse. After the final water rinse, the yarns were
exposed to air (skied) for another two minutes. The yarns were then
processed through a vat with cleaning agents (soaps) heated to
60.degree. C., then skied for another two minutes. The yarns passed
through yet another water rinse stage, before being again skied for
an additional 2 minutes before being dried for the last time before
weaving.
[0091] The CleanKore technology greatly simplified this
conventional method and resulted in tremendous water savings in
addition to producing a significantly larger and more consistent
core. The yarns began in a scour vat as before, but with caustic
chemistry being reduced from 150 g/L to a mere 3 g/L and the
immersion time reduced from 22 seconds to 12. The exit nip pressure
was increased from 4 bar to 5.5. Rather than skying the yarns
before immersion in sulfur, they first went through a water rinse
stage with minimized dwell time by threading the yarn path to a
minimal length. The rinsing of the yarns is with the intent to halt
the scouring of the yarns, preserving some of the original waxes
and oils inwards from the perimeter, or towards the core as one
views a yarn cross-section. The dwell time is understood to mean
the time between the scour tank and the rinse tank. Where the yarns
previously were skied for 120 seconds, they were instead passed
from the scour to the scour rinse on the shortest path achievable.
Yet another CleanKore feature was practiced where the immersion
time in the scour rinse was reduced to 7 seconds and the water flow
was increased, such that the pH of the scour rinse vat did not
exceed a pH of 9.9.
[0092] From the rinse vat the yarns proceeded to the dye vats.
Rather than one long saturating dye vat, the yarns were processed
through a first dye vat with an immersion time reduced to 11
seconds (from 19), and the temperature was lowered from 90.degree.
C. to 80.degree. C. After processing through each respective sulfur
dye immersion, the yarns experienced a similar 120 seconds of sky
time or oxidation. Typically, 1-3 dye immersions are used.
[0093] After the dye vats and air oxidation, the yarns were exposed
to a single water vat for 7 (from 19) seconds, then a
neutralization vat of acetic acid for another 7 (from 19) seconds,
and a final water rinse for 11 seconds (from 19) before being
steamed on the drying cans.
[0094] The CleanKore technology involved an increase of water flow
to the scour rinse and the two dye rinse tanks, but resulted in
bypassing of 2 rinse vats, as well as a soap vat.
[0095] When woven, these yarns proved to be within tolerance of the
target shade from a singular trial and resulted in a faster
industrial washdown with superior laser response, while still
retaining colorfastness resistant to the effects of consumer home
laundries similar to the conventional counterpart.
[0096] This example was carried out with water, energy, and
chemical savings The practice of the disclosed embodiments created
sulfur black dyed yarns which had superior ring dyeing effects,
resulting in a larger core with reduced dye penetration.
[0097] Oftentimes the yarns pass from the dye rinse stage to a
softener stage. The softener, as the name implies, is a chemical
bath that makes the more pliable, resilient, and lubricated for
weaving. The inventors have experienced multiple ranges operating
with softener vats operating at temperatures over 70.degree. C.
This high temperature tends to open the yarns unnecessarily. There
is a low risk of dye-fixing to the core of the yarns at this stage,
but back staining of insoluble dyes still requires rinsing. Steps
that can be taken to lessen this effect are beneficial. It is for
this reason that one feature of the invention is to lower the
temperature of the softener to the lowest temperature recommended
by the distributor, which is typically 50.degree. C.
[0098] After the nip roller from either the last rinse or the
softener stage, if one is present, the yarns typically proceed to
the drying cans. The drying cans are a series of rollers, but these
rollers are larger in diameter when compared with vat rollers, and
are heated, typically with steam. To further prevent the
unnecessary opening of the yarn fibers and in the continued effort
to conserve energy, one feature of this invention is to lower the
temperature of the drying cans as much as possible and still attain
an acceptable level of exit moisture. Exit moisture, as one can
infer, is the percentage of moisture content on the yarns as they
exit the drying cans. Quite often yarns are overdried on drying
cans that are operated at too high of a temperature and have exit
moisture of 5-7%. CleanKore technology optimization involves
controlling the drying can temperature, typically by controlling
steam flow, in order to obtain optimal exit moisture in a range of
8-12%, and ideally 10%.
[0099] The weaving process is a violent procedure where the now
dyed warp yarns are forced through a series of weft yarns. This
process involves profound amounts of friction. To minimize the
breakage that results from this friction, the yarns are processed
in a slashing, or sizing phase. There are additional benefits with
the use of sizing, but yarn strength, smoothness and the addition
of lubrication are the benefits these attributes provide in the
weaving process. The slashing phase occurs when dried yarns are
passed through a vat or vats of additional chemistry. Oftentimes
this chemistry is composed of water and a natural starch, such as
rice, potato, or cornstarch. In addition to the natural starches,
there are manufactured polymers that can be used in place of, or in
addition to the natural starches. Starches are typically sourced
for their price relative to the location of the mill. Plants in
China, India, and Thailand typically use rice starches or
synthetics. Sources in the United States typically use corn or
potato starch, as well as synthetics. The sizing application is
commonly done in tanks heated to as high as 95.degree. C. with high
concentrations that result in the unnecessarily high add-on
(percentage of the yarn weight increase after the sizing
application). This add-on can be as high as 8-9%, whereas the
preferred CleanKore technology related add-on is around 5% in
temperatures around 80.degree. C.
[0100] Another feature is the improved yarn characteristics that
are achieved as a result of the reduction of time spent in scour,
rinse, and dye vats. This time reduction is typically achieved by
changing what the inventors refer to as the "threading path." The
threading path is the path that yarns pass along through the
rollers on the dye range. The process of passing a yarn over a
roller under tension causes strain, which results in a slight loss
of integrity of the yarns. This loss of integrity of the yarns is
realized during the weaving process. Yarns that have undergone
excessive strain or have otherwise compromised integrity
occasionally experience breakage during the weaving process. The
more stress and strain yarns experience, the more regularly weavers
can expect breakage. Yarn breakage during weaving is a costly
issue. The reduction in the number of rollers with CleanKore
technology results in a substantial retention of yarn integrity
throughout the dyeing and weaving stages, saving costs through
reduction in labor requirements and improved weaving machine
efficiencies. Stronger yarns throughout the dyeing and weaving
process result in improved fabric strength (when compared to yarns
of identical characteristics dyed and finished similarly using
conventional practice) as a result of this warp yarn integrity
retention, which is one feature of the CleanKore technology.
[0101] Another embodiment of CleanKore technology is the humidity
control of the yarns before dyeing begins. Yarns that are stored in
arid areas absorb scouring and wetting agents faster and more
thoroughly than yarns that are stored at higher humidity. This
faster and more thorough saturation results in a more thoroughly
scoured yarn, given all other conditions are static. For this
reason, one feature is to assure that the yarns are stored at a
humidity that is less likely to result in this faster absorption.
Humidity is of course dependent on the climate. With many mills
located in desert-like climates, humidity control in areas where
the cotton and yarns are stored better prepares the yarns for
processing. Humidity control is dependent on the environment. In a
location having high humidity, such as Thailand, one would not dry
a yarn to 4% humidity, because the moist air will increase the yarn
back up to 5-6%. In dry locations, such as during the dry season in
India, one could dry the yarn to 4-5% with no problem.
[0102] Another feature of CleanKore technology is the more precise
control of line tension throughout the range. This feature is
relevant to both rope and slasher style ranges, but more so with a
slasher. The increase of line tension or the tautness of the yarns
throughout the range plays an important role in how readily the
yarns are penetrated by various chemistries. Increased tension
reduces the penetration of dyes and other chemistries. A reduction
in tension is often associated with an undesirable increase of
penetration by dye as well as other chemistry with which the yarns
are processed. Line tension may also be increased depending on the
twist multiple of the yarn.
[0103] An obviously tremendous expense in operating a dye range is
the purchase of the equipment that the dye range is composed of.
The anatomy of a given dye range is determined by the staff at the
dye range making the purchasing decisions, and the sales and
technical teams that sell the equipment. Quite often this
purchase/sale arrangement results in dye ranges that offer unique
limitations. When the arrangement results in a number of particular
vats that exceed the needs of standard CleanKore technology, the
inventors simply skip (eliminate) those boxes by threading over
them or through them without any application taking place, which is
a feature of the invention. Some of the vats can be easily
converted if necessary. In one location the range was such that it
lacked a scour rinse between the scour and the dye vat. In this
case, inventors converted the first dye box to a rinse box and
simply dyed in fewer succeeding boxes. Alternatively, the inventors
could have reduced the amount of scouring chemistry to a minimal
extent such as 0.5 or 1 gram per liter and attempted to counter
this low concentration with a full scour duration of 18-22 seconds
with the intent being that the increased immersion and dwell time
would have minimal effect and the contamination level in the first
dye tank would be marginalized.
[0104] The benefits of CleanKore technology are observable. In
addition to the realized effectiveness of the color removal
attempts made with washing and laser processing, the inventors have
discovered that the benefits of CleanKore technology are observable
through a microscope with correct lighting, particularly when a
single yarn is cleanly cut and properly positioned so it is aligned
with the viewing trajectory of the microscope. An important factor
in observing these benefits is lighting. When the surface of the
yarns is under-lit, it is difficult to see the demarcation between
the dyed ring and the yarn core. When the yarns are excessively lit
on the yarn cross-section, it is difficult to see most of the yarn
cross-section detail and coloring as a result of the abundance of
star-bursting that occurs. Star-bursting happens when a yarn
reflects too much light and rather than revealing the fibrous
detail of the cross-section, the area within a cross-section, or
the whole cross-section appears to be nothing more than a bright
spot in the picture, lacking detail. Excess light causes many cores
of different qualities to look so similar to the observer one could
have difficulty differentiating one from another.
[0105] The inventors discovered the correct lighting when they
observed these yarns under 40.times. magnification with 5000K led
(daylight) lighting. The inventors used a Samsung Galaxy Note 10
camera to take various pictures of the yarns with pro (manual)
shooting modes with exceptional results.
[0106] The inventors, using a microscope and market-leading mobile
phone cameras such as the cameras found in the Samsung Galaxy Note
20 Ultra, were able to take very clear pictures of the yarn cores
of conventionally dyed and CleanKore dyed yarns. Importing those
pictures into image editing software such as Adobe Photoshop
revealed that CleanKore technology repeatedly results in yarn cores
that are larger when compared to conventionally dyed yarns, with a
smaller perimeter of dye that more closely follows the shape of the
yarn. While comparing one yarn to another, the human eye is subject
to bias, memory lapse, and interpretation. In order to circumvent
this, yarns are viewed, and images are captured under the
microscope with the operator unaware of which yarns are control
yarns and which yarns are CleanKore yarns so as to remove bias.
[0107] The operator then opens the captured images in a software
editing program, such as Adobe Photoshop, as shown in FIG. 3.
[0108] Within the image editing software, the operator then removes
the side profile of the yarn, as well as non-yarn portions of the
image. This leaves an image containing only the yarn cross-section.
Using the image editing software, the operator can then accurately
determine the number of pixels that make up the total area of the
yarn cross-section. This number is recorded for comparison (see
FIG. 4).
[0109] Using the same image, the operator then removes what is the
darkest ring of dye around the perimeter leaving only the core, and
then again captures the number of pixels remaining in the image
(see FIG. 5).
[0110] By simply dividing the number of pixels in the core by the
number of pixels in the yarn cross-section, the operator can
determine the size of the core relative to the whole
cross-section.
[0111] By compiling ten or more results for each particular product
or style, the inventors have accounted for variances from one yarn
to another and averaged the results. With this procedure, the
inventors have found that CleanKore (CK) technology results in
yarns that have a core that is 15-50% larger than conventionally
dyed yarns. This effect is depicted in Table 1. Within Table 1 the
values for the results from Table 1 and FIG. 5 are shown in
highlighted text, as well as the result of the division of
core/center values revealing the percentage of the yarn
cross-section that consists of core area pixels.
TABLE-US-00001 TABLE 1 Control Yarn 703 Center Core % 1 129622
54725 42.21891 2 59966 22848 38.10159 3 61872 30363 49.07389 4
72440 38660 56.6444 5 46974 25840 55.00915 6 167311 52975 31.66259
7 198215 64692 32.63729 8 120933 48738 40.30165 9 241533 81523
33.75232 10 130733 68630 52.49631 Avg 42.88981 CleanKore Yarn 710
Center Core % 1 184104 131804 71.6 2 134782 75802 56.2 3 142957
95630 66.9 4 194935 103708 53.2 5 58956 48524 82.8 6 139254 95694
68.7 7 156657 89915 57.4 8 144910 70944 49 9 173770 113362 67.7 10
167320 80242 47.9 Avg 62.14 45% Larger
[0112] CleanKore technology offers a host of benefits that stem
from the reduced reliance on chemicals and energy during the dyeing
stage and techniques that result in a larger, whiter core within
the yarn. This larger, whiter core in the yarn means that less
time, energy, and water are spent removing the "ring" of dye to
access the variations in color that the white core offers. Sizing,
while offering solutions for weaving, creates a barrier to
realizing some of the benefits of the ring dyed effect. For this
reason, CleanKore technology is optimized with the use of the
natural starches with the order of preference being potato, rice,
and then corn starch, respectively. This order is determined by the
ease of which the starches can be removed after their purposes in
the weaving process have been realized. Potato starch is the
easiest to remove, with the shortest water cycle at room
temperature or with very little heat. Rice requires more time and
energy, and corn even more yet. The synthetics, on the other hand,
are particularly difficult to remove, requiring much higher heat
with the greatest amount of residual sizing on the yarns after
removal attempts. This order of preferred sizing is a critical
embodiment of the invention. Sizing, while wholly necessary for the
weaving process, is a liability to color removal processes such as
washing, laser, and hand-sand. Attempts to laser etch from the
surface of yarns result in first energies spent on the removal of
the starches, and then and only then can the dyes be removed. In
addition to acting as a barrier to dye removal, the starch's
exposure to the heat associated with laser processing creates an
ash layer that can be incredibly difficult to remove. In the
inventor's experience, the ash removal difficulties are paralleled
to the difficulties in the removal of the starches themselves. That
is to say, the ash created by lasering potato starch is easier to
remove than that of rice starch. The ash of corn starch is harder
yet, and the ash created by lasering the synthetic starches can
prove quite difficult and as a result, expensive to remove.
[0113] As the preservation of the waxes and contaminates in the
core of the yarn, one feature is the lack of treatment before the
yarns are processed on a dye range. Some mills prefer to
pre-mercerize their yarns. Mercerizing yarns typically involves
exposing the yarns to high doses of caustic at high temperatures
(>60.degree. C.) in order to strengthen and whiten the yarns.
This pre-mercerization leaves the yarns with a much whiter color
and opens the yarns for increased receptivity to dye penetration.
While the whiter core sounds ideal, the opening of the yarns and
the nature of higher caustic (and typically high temperatures) also
thoroughly cleans the yarns of their waxes and oils.
Pre-mercerization dramatically increases the efficacy of wetting
agents as the yarn fibers have opened relative to their original
state.
[0114] Similarly, yarn sourcing and processing can have an impact
on the efficacy of CleanKore technology and as a result, is a
feature. The inventors have recognized that cotton sourced with
longer fibers reduces the fuzziness of the spun yarn, which appears
to increase the density of the yarn and enhances the benefit of the
twist. This increased yarn density improves the attributes
associated with CleanKore technology, namely the dark ring dye with
the retained white core. Yarn sourced with high oil and wax
preserves a greater oil and wax content in the core, further
lessening the likelihood of scour and dye chemistries also greatly
improve the efficacy of the CleanKore technology and is, therefore,
a feature.
[0115] Another feature of this invention is the improved dye
removal characteristics associated with CleanKore technology. Dry
processing attempts to remove the dye using methods, such as the
application of laser energy as well as the manual hand sand
process, are undertaken to reveal a white core, or to reveal an
area where the dye is a lighter shade in purposeful patterns and
shapes. Laser application involves the firing of laser energy at a
garment, typically with a predetermined pattern, with the intent to
selectively remove dye from different areas of the garment. These
efforts are significantly improved in efficacy as well as the
efficiency with the use of CleanKore technology. CleanKore
technology reveals improvements in efficacy when it is possible to
successfully laser process garments that otherwise would not result
in desirable results. This is a common issue with very dark colors,
such as garments that have been dyed with sulfur dyes or an
inordinate amount of indigo dye. Traditional dyeing techniques
result in these garments being either incapable of being
successfully processed to current fashion standards, or they
require significant additional energy in various forms. These
additional energies can involve the application of chemistry,
laser, and/or hand sanding where the application of both is to
achieve target color, as well as the application of undesirable
potassium permanganate.
[0116] In the process of testing CleanKore technology treated
fabric for improved laser response, the inventors realized one
substantial hurdle was the elimination of potassium permanganate
spray and improving the overall efficacy of laser production is the
removal of the laser ash. For this reason, a series of tests were
conducted with various chemicals available to conventional
laundries. This resulted in a solution realized when the garments
are first processed in a cycle consisting of sodium percarbonate
added at a ratio of 10 grams per liter of water and sodium
carbonate added at a ratio of 4 grams per liter and washed for 10
minutes at a temperature of around 45.degree. C. The sodium
carbonate is added to the washing of the garments after being
sewn.
[0117] As mentioned previously, manufacturing often involves the
use of potassium permanganate. Referred to within the industry
simply as "PP spray," this chemical is a powerful oxidizer that
brings with it many potential hazards including the potential for
respiratory collapse, blindness, kidney damage, and possibly death.
The use of PP spray serves a singular purpose, which is revealing
or producing, lighter shades or whiter shades on previously dyed
yarns. The reduction or elimination of the industry's dependence on
PP spray is one of the features of this invention. As previously
stated, the improved and narrowed dyed ring vastly improves the
capabilities of other methods to reveal the lighter shades and
white core that lie underneath, making PP spray in all but the most
extreme of fashion instances (such as the requirement that the
appearance involve warp yarns whiter than their original color)
unnecessary. With the reduction in the application of PP spray,
CleanKore technology yarn dyeing also results in a water savings as
a dedicated cycle of filling a washing machine with a chemical to
neutralize the PP spray is also eliminated which saves a tremendous
amount of water worldwide, often in locations where it is a scarce
resource.
[0118] Hand sanding, laser processing, and PP spray are all
attempts at color removal that occur during what is typically
referred to as "dry processing." As mentioned previously, these dry
process steps are intent on removing the dye in patterns and
shapes, typically in an attempt to replicate the natural "wear"
that would otherwise occur over time but could be for patterning or
image placement. Wet processing is an attempt through batch
processing to treat multiple garments, typically with chemicals,
enzymes, and/or abrasives added to water. A typical stone washed
garment (see FIG. 6) reveals that there are areas on the garment
near and on seams that are darker than the majority of the garment.
This appearance is often sought after and requires significant
amounts of water, energy, time, chemicals, and abrasives to
achieve. Enormous washing machines are loaded with dozens of pairs
of jeans, water, and chemicals before being processed for up to 2
hours, oftentimes with multiple refills of water and chemicals.
This chemical and water-dependent tumbling procedure, often
involving the inclusion of pumice stones, slowly removes color from
the majority of the garment, revealing a lighter or whiter shade
than what is found on the original outer section of the yarn. The
further the dye has penetrated the yarn, one can understand simply
that more energy, time, and water is required to achieve a similar
shade. Implementing CleanKore technology yarn dyeing results in
garments that require substantially less effort in wet processing.
This summary of "less effort" amounts to washdown cycles being
15%-75% more efficient, with the most common result being 50% less
effort to achieve identical or near-identical shades. Laundries can
determine whether it is more desirable to use fewer chemicals, or
if it is preferred to use similar chemical levels to achieve
improved machine efficiency to save electricity, time or a
combination of both. This energy, water, time, and chemical savings
available during wet processing is one feature of CleanKore
technology. The improved machine efficiency results in less
electricity being consumed which in turn means less pollution in
the area from energy production, and water conservation can lead to
safer drinking water and more of it through a decrease in pollution
and water usage.
[0119] One feature is the pretreatment of the yarns in a
nonconventional way. Typically, when a mill or designer desires a
yarn that is whiter than its original, natural color,
pre-mercerization is used to treat the yarns before being used on
the dye range. Pre-mercerization is an aggressive, typically heated
bath of a high concentration of caustic that is intended to
strengthen and act as a whitening agent. Pre-mercerization uses the
same chemistry as the scouring process, but at higher temperature
and concentration. The issue with the pre-mercerization is that it
also strips the yarn of the natural waxes and oils, similar to the
scouring stage, but a much more extreme application results in much
more extreme results. An embodiment of this invention is to use an
actual bleach process using either chlorine or the more likely
sodium hypochlorite, even or calcium hypochlorite which could be
used along with wetting agents to remove the color from the yarns
before dyeing without excessive removal of the waxes and oils from
the yarn.
[0120] Although certain presently preferred embodiments of the
invention have been specifically described herein, it will be
apparent to those skilled in the art to which the invention
pertains that variations and modifications of the various
embodiments shown and described herein may be made without
departing from the spirit and scope of the invention. Accordingly,
it is intended that the invention be limited only to the extent
required by the appended claims and the applicable rules of
law.
* * * * *