Note: Descriptions are shown in the official language in which they were submitted.
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HIGH CONTRAST PATTERNING PROCESS AND PRODUCT
This invention relates to a process for generatiny
patterns exhibiting high visual contrast on textile
substrates, and novel products which may be produced
thereby. More specifically, one embodiment of this
invention relates to a process wherein individual
constituent fibers in an area on the surface of a textile
substrate defining a pattern are thermally conditioned or
treated to permit relatively rapid extraction of dye from
those fibers by a solvent, while adjacent fibers which have
not been so thermally conditioned or treated resist such
rapid dye extraction, thereby resulting in fabrics wherein,
following the controlled exposure to a suitable solvent, the
heat-treated pattern areas contain visually less dye than
adjacent9 solvent exposed pattern-complementary areas.
Processes for generating pattèrns on the surface of
textile substrates are well known in the art. Such
processes may or may not require the pattern-wise
application of dye to achieve a pattern, or even a
dye-defined pattern, on the substrate surface. Among those
processes which do not require the pattern-wise application
of dye are included processes wherein heat, for example3
from a heated embossing roll or in the form of impinging
heated fluid streams, is directed onto the substrate surface
in a pattern conflguration prior to a dyeing step. The
thermally treated poltions ot the ~urface acc~pt dye to a
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different (generally greater) degree than do the untreated
portions, thereby usually resulting in pattern areas having
higher, visually contrasting dye concentrations. Other
processes rely on a variety of physical effects to de~ine or
establish patterned areas on the substrate surface. For
example, some processes rely on physical compression and
perhaps heat setting of individual fibers to imprint the
surface and thereby define a pattern. Other systems may
rely on fiber entanglement to yield visually distinct areas
on the substrate surface.
A process disclosed in commonly assigned Canadian
Patent No. 1,154,581 granted October 4, 1983,
relies upon streams of heated fluid, which are mad~ to
impinge upon the substrate surface in a pattern
configuration, to selectively shrink, melt, or otherwise
thermally deform or distort individual yarns or portions of
individual yarns comprising the substrate surface, thereby
producing visually distinct areas on the substrate surface
in those areas containing yarns exposed to the heated ~luid
streams.
This technique can prGduce patterns which are quite
detailed and which, under some circumstances, can achieve
rather high levels of visual contrast between pattern and
pattern-complementary (i.e., background) areas, even though
not requiring the pattern-wise application of dye. This is
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particularly true if the substrate is, for example, a pile
fabric and the pile yarns have been heated sufficiently to
induce substant1al thermally-induced longitudinal shrinkage
among the individual pile yarns. The resulting sculptured
or surface contoured effect can result in dramatic contrast
levels between pattern and pattern-complementary areas,
provided the sur~ace is appropriately illuminated. However,
the degree of contrast is often heavily dependent upon the
type and direction of the incident illumination. When
non-pile textile substrates are patterned using this
technique, the individual fibers are softened and may
undergo some shrinking or melting, contrast, however, is
frequently limited even under optimum illumination with such
fabrics. Using a dye which is selectively applied in
pattern areas only can impose formidable constraints if fine
detail, or strict reproduceability, as production speed, and
inventory flexability, is desired. Colors must be carefully
matched, dye runs coordinated and scheduled, and~ of course,
the dye must be applied with great precision and accuracy.
These constraints have been formidable.
It is therefore desired to have available an economical,
commerclally practical process wherein patterning may be
achieved using the pattern-wise application of heat or other
conditioning agent ? rather than the pattern-wise application
of dye, to individual yarns on the substrate surface, and
whereln the degree of vl~-al contrast oetween pattern and
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pattern-complementary areas on the substrate surface may be
controllably varied from relatively low to relatively high
values, and wherein the perceived contrast is not
significantly dependent upon the nature of the illumination.
The process of this invention involves the treating or
conditioning, by physical or other means, of individual
yarns in the pattern areas of the substrate to permit the
subsequent selective extraction of dye in treated yarns
processed in a controlled solvent-based extraction step,
which extraction step has substantially no visible effect on
adjacent, untreated yarns forming the pattern-complementary
areas of the substrate. The dye may be applied to the yarns
either prior to or following the treating or conditioning
step. The role played by the treating or conditioning agent
in this invention may be thought of as being somewhat
similar to that of a catalyst, in the sense that the chosen
solvent extracts dye with much greater speed from the
treated yarns than from the untreated yarns. Generally
speaking, the chosen solvents useful in the practice of this
invention will, given sufficient exposure, extract dye from
untreated areas as well as treated areas, and perhaps to the
same extent, but will not do so at the same rate.
Figure 1 depicts d pile fabric, comprised of
thermoplastic and non-thermoplastic yarns, in which heat
conditioning has caused thermal deformation, in the form of
longitudinal shrinkage, to individual thermoplasti G pi le
yarns; dye has then been selectively extracted from those
thermally deformed fibers.
Figure 2 depicts a pile fabric in which heat
conditioning has caused thermal deformation, in the form of
longitudinal shrinkage, to tufts or groups of thermoplastic
pile yarns; dye has then been selectively extracted from
those thermally deformed yarn groups.
Figure 3 depicts a flat knitted fabric comprised of
thermoplastic yarns wherein heat conditioning has caùsed
thermal deformation, in the form of melting and/or fusing of
individual yarns; dye is selectively extracted from the
deformed region of the fabric.
Figure 4 depicts a textile substrate in which dye has
been selectively extracted from the heat-treated
diamond-shaped areas, in accordance with the teachings of
this in~ention.
In one preferred embodiment of the invention, a textile
fabric comprised of polyester (e.g., polyethylene
teraphthalate) yarns which have been convent;onally dyed
with a disperse dye is impinged with heated streams of
fluid, for example, air, in a pattern-wise configuration by
an apparatus similar to that disclosed in commonly assigned
Canadian Patent No. 1,154, 581 referenced
above. This apparatus is discussed herein as merely one
example of an apparatus which may be used to practice this
inven~ion; commonly assigned U 5. Paten~ No. ~,364,156,
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also incorporated by reference herein~ further defines a
manifold which may prove advantageous when used in
conjunction with the apparatus of Canadian Patent No.
1,154/581. It is believed any means by which
appropriate amounts of heat may be suitably applied in a
pattern-wise configuration to the yarns comprising the
surface of the textile substrate to be patterned may be
employed. For example, a laser beam of suitable power and
intensity9 directed onto or over the substrate surface in a
pattern configuration, may be used instead of heated air
streams.
It is theorized that, where thermal energy is used to
condition the yarns9 the heat tends to induce a decrease in
the internal orientation of at least portions of individual,
untensioned yarns in those pattern areas where the maximum
rate of solvent extraction of dye is desired. The decrease
in orientation is thought to promote the entry of the
solvent into the yarn interior, perhaps by generating voids
between adjacent constituent molecules, and thereby
accellerate the dye extraction process. It is also
theorized-that thermal conditloning may tend to cause radial
migration of dye molecules ~rom the yarn interior toward the
yarn sur~ace which, contributes to the observed acc~llerated
rate of dye extraction by the solvent in thermally treated
yarns. Generally speaking, thermal conditioning of
thermoplastic yarns is accompanied by ~hermal deformation or
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distortion of the yarns, e.g., softening, longitudinal
shrinking, melting, or fusing of individual yarns. These
effects are schematically depicted on various substrates in
Figures 1 through 3. It is believed maximum rates of
selective dye extraction in accordance with the teachings of
this invention mdy be expected from those thermoplastic
yarns or portions of yarns which exhibit such thermally
induced deformations, as compared with thermoplastic yarns
in which no thermal deformation is observed. However, such
softening, shrinking, melting, or fusing, or other readily
observable, external effects are not believed to be
necessary to the practice of this invention. The degree to
which such observable effects occur depends upon many
factors, such as the type and composition of yarn used, the
degree to which the individual yarns are free to shrink, the
nature of the applied heat, etc.
It is also believed that conditioned polymeric yarns
have increased voids between adjacent polymer molecules
within the fibers comprising the yarns, as compare~ to
unconditioned yarns of the same type, thereby enhancing the
migration rate of solvent molecules into and out of the
yarns.
The following table was prepared to quantify the effects
of therMal conditioning on one~example of a polyester yarn,
using a preferred suitable solvent. A package of yarn, 20/2
T-811W Bright DACRON ~(DACRON is a trademark of DuPont),
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manufactured by Milliken & Company from DuPont polyethylene
terephthalate fiber, was dyed in a laboratory package dye
machine using Eastman Polyester Blue GLF (Color Index Name
Disperse Blue 27). Lengths of this yarn were heat treated
by immersion for 5 seconds in a fluidized bed, Model SBS-2
distributed by Fisher Scientific Company of Pittsburg,
Pennsylvania, over a range from 300F. to 500F., in
increments of 25F. Measurements of length before and after
heat treatment allowed calculation of the percent shrinkage
at each temperature. Standard lengths were then solvent
extracted by immersing them in 5 ml of methylene chloride at
room temperature for one minute and then removing the yarn
from the solvent. The UV-Visible spectra of these extracts
were then recorded to yield the absorbence attributed to the
blue dye at a wavelength of between 592 and 595
millimicrons~ thereby giving an indication of the amount of
dye extract by the solvent.
The results are tabulated below:
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Table 1
% Shrinkage, Absorbance Of Heat Treated Polyester Yarn
5Temperature % ShrinkageRelative Absorbance
300 0 .048
325 0.2 .092
350 0.~ .108
375 3.5 .057
400 6.8 .043
425 9.6 .070
450 20.5 .349
475 28.2 .699
500 Melted
It can be seen from this table that, for this particular
yarn/solvent system, the rate of dye extraction generally
increases after brief thermal conditioning at temperatures
above about 300F., and increases dramatically after brief
thermal conditioning at temperatures extending from about
425F. to somewhere between about 475F. and 500F., i.e., a
temperature just below the melting point of the
unconstrained yarn. Where the yarn is constralned, somewhat
higher temperatures, i.e., 500F. or above, may be employed
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to generate increased shrinkage and increased dye extraction
rates.
After the fabric has been suitably heat treated in the
desired pattern configuration, the fabric is then exposed
for a controlled period of time to a solvent which, during
that time period, selectively extracts dye from the heat
treated areas only, and which has relatively little or
substantially no effect upon those portions of the fabric
surface which have not been heat treated in accordance with
the teachings of this invention. There is no requirement
that the heat treated fabric be immediately exposed to the
solvent, or be stored under any particular set of conditions
following the pattern-wise heat treatment of the fabric.
There is also no requirement that the fabric be dyed prior
to the pattern-wise application of heat; good results may be
obtained if a fabric is first subjected to the pattern-wise
application of heat, then piece dyed, then exposed to a
solvent, all in separate independent steps, in accordance
with the teachings of this application. Because under such
conditions the heat treated areas tend to pick up more dye
than the untreated areas, extraction times may be extended,
because more dye may be required to be extracted.
Any suitable solvent may be used. Solvents which have
been used with fabrics containing polyester yarns which were
dyed using disperse dyes include hot perchloroethylene and
19 ~ trichloroethane. Other solvents which may be found to
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be satisfactory may be found in Table II of the technical
artic1e "Interactions of Nonaqueous Solvents with Textile
Fibers - Part I: Effects of Solvents on the Mechanical
Properties of a Polyester Yarn" by A. S. Ribnick, H.-D.
Weigmann, and L. Rebenbeld, appearing in the Textile
Research Journal, December 1972, at pages 720-726 ~Table I I
at page 722) as well as in Table I of the technical article
"Interactions of Nonaqueous Solvents with Textile Fibers -
Part II: Application of the Solubility Parame-ter Concept to
Polyester Fiber-Solvent Interactions" by B. H. Knox, H.-D.
Weigmann, and M. G. Scott, appearing in the Textile Research
Journal, March, 1975 at pages 203-217 (Table I at 206); the
contents of these two tables are hereby expressly
incorporated by reference.
A preferred solvent for polyester yarn/disperse dye
combinations is methylene chloride, which may be used at
room temperature and which is capable of extracting
substantial quantities of disperse dye from pattern-wise
heat treated polyester relatively quickly. In one
embodiment, polyester-containing fabric which has been heat
treated in a pattern-wise configuration may be immersed in a
bath of methylene chloride at room temperature and agitated
for a short period of time to assure proper clrculation of
the solvent in the vicinity of the yarns comprising the
patterned areas of the fabrlc. The methylene chloride ::
solvent can, in a matter of 30 to 60 seconds or less,
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extract substantially all the visible dye from those pattern
areas of the fabric which have been heavily heat treated.
During the same time period, the solvent will extract
visably less dye from pa~tern areas, or portirons of
individual yarns, which have been less heavily treated,
i.e., exposed to lower temperatures, and will extract
substantially no dye from those areas or yarns, or portions
of yarns, which have not been heat treated. Using warm or
hot methylene chloride solvent produces the same selective
extraction effects, but within a substantially shortened
time period virtually complete dye extraction may be
achieved in heavily patterned areas in a matter of a few
seconds. It must be remembered that if solvent exposure
time is not monitored carefully, complete dye extraction
will occur in lightly treated or non-treated areas as well.
Means other than immersion may be used to bring the
fabric ;nto contact with the solvent if desired, e.g., the
solvent may be sprayed on the fabric. It is also
contemplated that, following application of the solvent,
physical agitation of the yarns, to wash dye saturated
solvent from the surface may be used to facilitate the
extraction process. Means for halting solvent action may
vary. Most simpley, of course, the solvent may be washed or
otherwise removed From the substrate surface after the
desired "residence time" or exposure time has passed.
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It is preferred that the chosen solvent be one which is
not readily flammable, and of course should be one which is
neither grossly toxic to humans nor destructive to the yarns
used. It is believed that suitable solvents should be
selected from those solvents having a hildebrand solubility
parameter ( ) which is appropriate to the yarn of
interest. It has been found, for example, that for yarns
consisting essentially of polyethylene teraphthalate (
10.7), workable solvents should have hildebrand solubility
parameter values within the range of about 8 to about 14.
Solvents having values closest to 10.7 do not necessarily
result in maximum dye extraction rates and are not
necessarily preferred over other solvents having more
extreme values. Factors such as the size and therefore the
accessibility of the solvent molecule relative to the voids
between the polymer chains within the fi~ers which make up
the yarn must be accommodated. High solvent migration rates
are desirable. Solvents having values substantially higher
or lower than 10.7 may interact quite well with different
portions o~ the polyethylene teraphthalate molecule and
produce high dye extraction rates. It has been found that
suitable solvents having solubility~parameter values between
about 9 and~about 10, and also between about 11.5 to about
13, often work quite well, suitable solvents from the former
group tend to interact well with~the aromatic portion of;the
polyethylene teraphthalate molecule, while solvents from the
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latter group tend to interact well with the aliphatic
portion of that molecule.
The following Examples are intended to describe
particular applications of the invention, and are not
intended to be limitins. The device used to pattern the
fabric with streams of heated or hot air was similar to
those devices disclosed in commonly assigned Canadian
Patent No. 1,154,581 and U.S. Patent No. 4,364,156,
referenced above.
Example 1
A 100% polyester napped pile fabric having a weight of
10 oz. per square yarda identified by Milliken & Company as
Style g301, was conventionally dyed with disperse dyes to
give a uniform medium brown color. The fabric was then
treated with streams of hot air from the heated air devlce
described hereinabove to generate a sculptured pile fabric
having a pin dot array of depresseda thermally shrunken
yarns. The fabric speed in the device was 6.5 ypm, the
manifold air temperature was about 670F. The coloration in
the sculptured prior to exposure to the solvent areas was
slightly darker than in the background area, where the pile
remained substantially erect. The patterned fabric was
immersed in a bath of methylene chloride at 23C. for one
minute~, removed, and dried in a stream of room temperature
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air. When completely dry the fabric exhibited a pattern of
very light brown sculptured dots on a background
substantially unchanged in color. The contrast exhibited by
the pattern areas on the treated sample was excellent, and
the pattern was very easy to see from any angle.
Example 2
A 44 gauge double needle bar raschel knit polyester pile
fabric, identified by Milliken & Company as Style 6590
having a weight oF approximately 9 oz./yd.2 was dyed with a
disperse dye to give a uniform deep blue color. This fabric
was treated with streams of hot air using the device
disclosed above to yield a dot array of thermally shrunken
pile. The fabric speed in the device was 25 ypm; the
manifold air temperature was about 820F. When treated with
methylene chloride as described above for 1 minute, removed
and air dried, the final product exhibited a uniformly deep
blue field with a substantially white pin dot array,
corresponding exactly to the shrunken pile areas,
superimposed thereon.
Example 3
A raschel knit pile fabric of 100% polyester, identlfied
by Milliken & Company as Style 180 having a weight of
~ approximately 5 oz./yd.2 was dyed to a uniform green color
with disperse dye.~The~fabrlc WdS treated with streams of
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hot air in pattern configuration using the above-referenced
device. The fabric speed in the device was 7 ypm; the
manifold air temperature was about 700F. A sculptured
image was obtained which was difficult to read at all angles
of light. The fabric was then dipped in methylene chloride
at 23C. for 30 seconds, removed and dried with a stream of
cool air to yield a highly contrasting desiyn of white
ayainst a green background that was much more readable than
the untreated patterned fabric.
Example 4
A 100% polyester knit fabric (interlock) manufactured by
Milliken ~ Company and identified as Style 2651 having a
weight of 3.0 oz.yd. was dyed to a deep blue shade using
disperse dye and imaged by computer controlled streams of
heated air using the above-referenced device. The fabric
speed in the device was 3.75 ypm, the manifold air
temperature was about 8Z0F. Prior to exposure to the
solvent, the image was darker in the heated area. When
dipped in methylene chloride at 23C. for 30 seconds and air
dried, the imaged area became lighter. A second portion of
the same fabric, similarly patterned and exposed to
methylene chloride for 60 seconds, exhibited contrast which
was even greater, with the color of the unimaged area
remaining constant.
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Example 5
A woven fabric containing an intima~e blend of polyester
and cotton in the ratio 65/35 manufactured by Milliken &
Company and identified as Style 2602, weighing approximately
4.75 oz./yd. was union dyed to a navy blue shade. The
fabric was imaged with hot air streams to yield a diamond
pattern with flowers in the center, using the
above-referenced device. The fabric speed in the device was
6 yp~, the manifold air temperature was about 700F. On the
dark navy fabric, there was only slight contrast between the
imaged and the unimaged areas. After dipping in methylene
chloride at 23C. for 1 minute, the dye was extracted from
the polyester yarns that had been thermally tranformed by
the hot air while the dye in the cotton fibers remained
unaffected. The result was a light blue pattern on a darker
navy background due to extraction of the dye within the
polyester fibers.
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A napped woven fabric containing a disperse-dyeable
polyester yarn in the filling direction and a
cationic-dyeable polyester yarn in the warp direction was
woven in such a way that, after cross-dyeing, napping
created a sculptured effect consisting of square-shaped
non-pile areas, approximately 0.1 inches per s;de, which
appeared black (cationic dye) in a~field of grey (dispersed
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dyed nap). The fabric was manufactured by Milliken &
Company and identified as Style 8317 having a weight of
approximately 10 oz./yd. . The fabric was imaged with a
stream of hot air using the above-referenced device. The
fabric speed in the device was 6.75 ypmj the manifold air
temperature was about ~70F. The fabric was immersed in
methylene chloride at 23C. for 1 minute, then dri~d. The
resulting pattern showed a highly contrasting white pattern
area, and a black pin dot on a grey background. The
resulting effect was multicolor and showed good contrast
with the cationic dye removed to a much lesser extent, if at
all, by the solvent extraction process.
Example 7
A woven polyester fabrlc having both cationic-dyeable
polyester yarn and disperse-dyeable polyester yarn,
identified as Style 8327 having a weight of 9.5 oz./yd.2 was
cross-dyed and then patterned with a stream of heated air at
760F. in the above-referenced device. Fabric speed was
6.75 ypm. The patterned fabric was then dipped in methylene
chloride for 1 minute at 23C. After 1 minute the sample
was removed and dried. It showed strong contrast where the
hot air had impinged, glvlng very light diagonal blue line
pattern against a field o~ medium-to-dark blue yarns.
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Example 8
The fabric of Example 1 was similarly treated with hot
air. The treated fabric was then immersed for 5 seconds in
a bath of methylene chloride heated to 35C. The results
after removal from the solvent and drying were substantially
identical to those achieved in Example 1.
Example 9
The procedures of Example 1 were followed, except that
acetone heated to 53C. was substituted for methylene
chloride. The results were similar to those achieved in
Example 1.
Example 10
The procedures of Example 1 were t`ollowed, except that
1,1,1-trichloroethane at 70C. was substituted for the
methylene chloride. The results were similar to those
achieved in Example 1.
Example 11,
The procedures of Example l were followed, except that
perchloroethylene at 95C. was substituted for the methylene
chloride,~and the exposure time was extended to S minutes.
~The results were sim11ar~to those~achieved 1n Example 1.
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Example 12
The procedures of Example 1 were followedJ except that
ethanol at 73C. was substituted for the methylene chloride,
and the exposure time was extended to 5 minutes. A very
slight change in the visual dye concentration was observed
in the treated areas.
Example 13
The procedures of Example 1 were followed, except that
the heat treatment with hot air streams was done prior to
conventional dyeing. The resulting fabric contained dark
brown dots on a medium brown fieldO Exposure of the
patterned fabric to methylene chloride for one minute at
23C. results in a noticeable visual lightening of the dot
areas. Further exposure, for a total exposure time of 5
minutes, resulted in a fabric exhibiting light beige dots on
a medium brown field.
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