U.S. patent application number 14/703514 was filed with the patent office on 2015-08-20 for articles of ignition resistant cotton fibers.
This patent application is currently assigned to Carbtex Technology, Inc.. The applicant listed for this patent is Carbtex Technology, Inc.. Invention is credited to David M. Hall, Francis P. McCullough.
Application Number | 20150233022 14/703514 |
Document ID | / |
Family ID | 53797593 |
Filed Date | 2015-08-20 |
United States Patent
Application |
20150233022 |
Kind Code |
A1 |
McCullough; Francis P. ; et
al. |
August 20, 2015 |
Articles of Ignition Resistant Cotton Fibers
Abstract
A bi-regional fiber with a cellulosic core and a wax outer
sheath is disclosed. The sheath can comprise high melting
temperature wax. The fiber may be produced by processing the
natural fiber at temperatures less than 70.degree. C. The fiber can
be processed in a standard manner such as, for example, a Keir
process which may include bleach at approximately 100.degree. C.
with a wax subsequently added at a temperature sufficient to
disperse the wax over the fiber surface. The fibers are ignition
resistant as measured by industry standard tests. The wax may
comprise from about 0.4 to 25 percent or greater of the fiber by
weight. The wax may be natural wax, synthetic or emulsified wax or
blends thereof. The bi-regional fibers can be blended with other
fibers including BRCF fibers to create fire resistant fabrics
including clothing, blankets and household materials.
Inventors: |
McCullough; Francis P.;
(League City, TX) ; Hall; David M.; (Auburn,
AL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Carbtex Technology, Inc. |
Dickinson |
TX |
US |
|
|
Assignee: |
Carbtex Technology, Inc.
Dickinson
TX
|
Family ID: |
53797593 |
Appl. No.: |
14/703514 |
Filed: |
May 4, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14071432 |
Nov 4, 2013 |
|
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14703514 |
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Current U.S.
Class: |
428/221 ;
156/180; 2/171; 2/207; 2/211; 2/227; 2/239; 2/400; 2/69; 2/74;
2/90; 2/93; 427/324; 428/375 |
Current CPC
Class: |
D06L 4/24 20170101; D06M
13/224 20130101; Y10T 428/2933 20150115; D06M 2101/06 20130101;
Y10T 428/249921 20150401; D06M 15/327 20130101; D06L 4/13 20170101;
D01F 8/02 20130101; A41D 31/08 20190201; D06L 4/70 20170101; D06M
15/70 20130101; D06L 4/12 20170101; D06M 2200/30 20130101 |
International
Class: |
D01F 8/02 20060101
D01F008/02; D06M 15/70 20060101 D06M015/70; D06M 15/327 20060101
D06M015/327; D06L 3/14 20060101 D06L003/14; A41D 31/00 20060101
A41D031/00 |
Claims
1. A bi-regional cotton fiber comprised of a cellulosic center and
an outer surface comprised of a wax.
2. The bi-regional fiber of claim 1, wherein the fiber is
bleached.
3. The bi-regional fiber of claim 2, wherein the fiber is bleached
with chlorine, ozone, peroxide, hypochlorite or a combination
thereof.
4. The bi-regional fiber of claim 1, wherein the wax comprises at
least 0.4 percent by weight of said fiber.
5. The bi-regional fiber of claim 1, wherein the wax comprises from
about 0.4 percent to about 25 percent by weight of said fiber.
6. The bi-regional fiber of claim 1, wherein the wax comprises
about 14 percent to about 16 percent by weight of said fiber.
7. The bi-regional fiber of claim 1, wherein the wax comprises is a
natural wax, a synthetic wax, an emulsified wax or a mixture
thereof.
8. The bi-regional fiber of claim 7, wherein the natural wax is a
cotton wax, a jojoba wax, a soy wax, a carnauba wax, or a
combination thereof.
9. The bi-regional fiber of claim 1, wherein the wax has a melting
point temperature of about 70.degree. C. or greater.
10. The bi-regional fiber of claim 1, wherein the wax has a melting
point temperature of about 90.degree. C. or greater.
11. The bi-regional fiber of claim 1, which has at least 10 percent
greater tensile strength as compared to natural cotton fibers.
12. The bi-regional fiber of claim 1, which has at least 20 percent
greater tensile strength as compared to natural cotton fibers.
13. The bi-regional fiber of claim 1, further comprising applying a
saponified acid or derivative thereof to the outer surface of the
fiber.
14. The bi-regional fiber of claim 13, wherein the saponified acid
or derivative thereof comprises lauric acid, myristic acid,
palmitic acid, stearic acid, oleic acid or combinations
thereof.
15. The bi-regional fiber of claim 1, which is fire retardant
and/or ignition resistant.
16. The bi-regional fiber of claim 15, which meets or exceeds a
vertical burn test conducted according to FAR 25.853(b).
17. The bi-regional fiber of claim 1, which contains no harmful
chemicals.
18. The bi-regional fiber of claim 17, wherein the harmful
chemicals comprise organohalogens.
19. The bi-regional fiber of claim 1, which has reduced water
absorption as compared to a natural cotton fiber.
20. A material comprised of a plurality of the bi-regional fibers
of claim 1.
21. The material of claim 20, which is fire retardant and/or
ignition resistant.
22. The material of claim 20, which has reduced water absorption as
compared to a natural cotton fiber.
23. The material of claim 20, which has a wrinkle resistance
greater than conventional cotton.
24. The material of claim 20, further comprising additional
fibers.
25. The material of claim 24, wherein the additional fibers
comprise natural fibers, synthetic fibers, carbonaceous fibers, and
combinations thereof.
26. The material of claim 24, wherein the synthetic fibers comprise
polyester.
27. The material of claim 26, wherein the synthetic fibers comprise
about 50 to about 90 percent polyester and about 10 to about 50
percent bi-regional fibers.
28. The material of claim 25, wherein the carbonaceous fibers are
flexible bi-regional carbonaceous fibers.
29. The material of claim 20, which comprises apparel for infants,
toddlers, children or adults.
30. The material of claim 29, wherein the apparel comprises shirts,
socks, pants, sweaters, sweats, gators, hats, scarves, coats,
undergarments, sportswear, skirts, dresses, tops, blankets, and
designs and combinations thereof.
31. The material of claim 29, wherein the apparel is suitable for
wear in environments wherein conditions are greater than and/or
less than body temperature.
32. A method for manufacture of a fiber comprising: bleaching a
cotton fiber; and applying a wax to the fiber.
33. The method of claim 32, wherein bleaching comprises treating
the fiber with chlorine, ozone, peroxide, hypochlorite or a
combination thereof.
34. The method of claim 32, wherein bleaching is performed at about
40.degree. C. or less.
35. The method of claim 32, wherein bleaching is performed at room
or ambient temperature.
36. The method of claim 32, wherein bleaching is performed at a pH
of between about 6 and about 8.
37. The method of claim 32, wherein the fiber comprises ignition
resistance without added harmful chemicals.
38. The method of claim 32, wherein no wash step is performed after
bleaching and before application of the wax.
39. The method of claim 32, further comprising adding polyester
fibers.
40. The method of claim 39, wherein the polyester fibers were
treated with a solution of a hydrolyzed partial condensation of
trimethoxy methyl silane.
Description
REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation-in-part of U.S.
application Ser. No. 14/071,432 entitled "Novel Ignition Resistant
Cotton Fiber, Articles made from Ignition Resistant Cotton Fibers
and Methods of Manufacture" filed Nov. 4, 2013, which is entirely
incorporated by reference.
BACKGROUND
[0002] 1. Field of the Invention
[0003] The present invention is directed to ignition resistant
and/or flame retardant whole cotton fibers, and whole cotton fibers
having a bleached cellulose region at the core and an outer region
comprised a wax sheath or surface. In particular, the invention is
also directed to methods for the manufacture of the ignition
resistant whole cotton fiber, and to articles made from a
multiplicity of said whole cotton fibers.
[0004] 2. Description of the Background
[0005] Cotton is a natural fiber and is renewable. That is, a new
crop can be grown each year. Most synthetic fibers are made from
petroleum which is not a renewable resource. Cotton has been known
for thousands of years, and accordingly, the physical and chemical
properties about cotton are well known. Because of a unique
chemical nature, cotton can be made to be fire retardant, have
wash-wear qualities, and be wrinkle free, among other properties.
Cotton also can be blended with other textile fibers to enhance the
overall performance of the blended fabric.
[0006] According to Cotton Inc., the US produced 15.5 million bales
of short staple cotton and 583,000 bales of long staple cotton in
2014. Each bale weighs 480 pounds. This represents only a small
fraction of the world cotton production. This converts to 5.56
million metric tons of short staple cotton and 140,000 metric tons
of long staple cotton produced in the USA. The State of Texas is
the largest producer accounting for 40 percent of this crop
followed by Georgia, Mississippi, North Carolina, Arkansas and
Alabama.
[0007] Raw cotton, in other words the unprocessed material obtained
from plants, like all vegetable matter contains minerals, resins,
gums, protein, tannins, oils and waxes and carbohydrates in
addition to cellulose. Cotton normally has to be purified to remove
these products from the primary cellulose polymer substrate.
Natural cotton is typically bleached in either the yarn form or the
fabric form. This involves boiling the cotton for 30 plus minutes
in a strong alkaline solution. This process cleanses the cellulosic
part of the cotton and removes the natural wax on the outside of
the cotton.
[0008] Most of the unwanted portions of the cotton plant material
are removed in a "Kier" boil process. This has become the standard
treatment process in which caustic soda (NaOH) and other processing
aids are employed at temperatures of up to 100.degree. C. to
solubilize and remove impurities. The oils and waxes are
saponifiable and removed by this preparation process. Continuous
processes have been developed which utilize a steam treatment
(100.degree. C.) to speed up the process and reduce the time
required by the Kier (batch) method. A comparison of the
composition of raw cotton versus a Kier like treatment is shown in
Table 1.
TABLE-US-00001 TABLE 1 Percent Composition of Cotton: Raw vs. a
Kier* Treatment Raw Cotton KIER Cellulose 80-85 99.1-99.5 Wax
0.4-1.0 0.01-0.15 Ash 0.8-1.8 0.05-0.075 Pectin's 0.4-1.1 Nil
Protein (Nitrogen) 1.2-2.5 0.05-0.10 Pigment, Resin 3-5 Nil
Moisture 6-8 Nil *(Mathews' Textile Fibers, 5.sup.th ed. Wiley
& Sons, NY, 1947 p, 100)
[0009] Virtually all impurities are removed by Kier boil treatment.
Color is removed by a subsequent bleaching process normally
employing either peroxide or hypochlorite process which removes the
color to the desired degree of whiteness. Following these
treatments, the cotton fabric is ready for numerous after-treatment
processes such as dyeing by any of a variety of methods, conversion
to a wash-wear, conversion to flame and/or ignition resistance
and/or other treatments, including combinations of all of the
above. Further treatments to enhance the utility of treated cotton
fabric or cotton fabric blends are known.
[0010] The wax in the cotton fiber is not one having a single
component, but is thought to have a blend of complex esters, acids
and alcohols. The waxes are thought to have a composition involving
C.sub.24-C.sub.34 primary alcohols as well as other complex
mixtures and a melting point of about 77.degree. C., a density of
0.976, an acid value of 29, saponification value of 57 (after
acetylation, 137), an acetyl value of 84, an iodine number of 27,
and 68% of un-saponifiable material (having an acetyl value of
123--indicating an absence of wax esters and a large proportion of
free wax alcohols). It is probably the free wax alcohols that
survive the treatment conditions outlined in the Kier and like
processes. The purpose of the wax in the fiber is to protect the
cotton seed from the harsh environments it may be subjected to
prior to spring planting. Loose raw cotton will float on water for
months; hence the cotton seed is protected against winter rains
damage. Still, it is these wax components that survive the
processing treatments which results in the surprise benefits of
ignition resistance cotton.
[0011] To reduce the inherent flammability of cotton fabrics,
cotton fiber can be combined with flame and/or ignition resistant
fibers, such as synthetic fibers. For apparel use modacrylic fibers
and matrix fibers of vinyl/vinyon, among others, have been used.
The resulting fabrics frequently lack the performance properties
and consumer appeal of pure cotton fabric. Fiber composed of 50
percent vinal and 50 percent vinyon, for example, is not strong
enough to form its own fabric and is not easily dyed. Another
disadvantage of this method of producing fire resistant fabric is
that yarns containing two or more fibers with different
flammability characteristics which tends to produce fabrics having
non-uniform cross-sectional areas, and therefore, non-uniform fire
resistant characteristics.
[0012] Alternatively, cotton fabric can be treated with flame
retardant chemicals and/or chemicals that promote ignition
resistance that change or interrupt the burning process known as
pyrolysis. However, cotton fabric treated with such chemicals lack
the performance properties and consumer appeal of pure cotton
fabric. Most of these treatments involve harsh chemicals which are
very unfriendly to the environment. Several have also been linked
to health problems in infants and newborns. For this reason most of
the newborn and infant bedding and sleepwear has been switched to
100 percent polyester.
[0013] During pyrolysis most textile materials must first undergo
decomposition to form volatile combustibles before they will burn.
Decomposition occurs when the textile material is exposed to a
sufficient source of heat. The decomposition temperature for
textile materials is dependent upon the composition of the material
and is different for different fibers. When the textile material
decomposes, volatile materials are formed. The volatile materials
ignite in the presence of oxygen to produce heat. The heat produced
during pyrolysis may cause further decomposition of the textile
material leading to its complete destruction.
[0014] The application of flame retardant chemicals or chemicals
that provide ignition resistance interrupt pyrolysis. For example,
the flame retardant or ignition resistance may be converted upon
heating into acids and bases that catalyze decomposition of the
textile at lower temperatures than are required for the formation
of volatile combustibles. Compounds containing phosphorus are
converted to acidic materials that catalyze the thermal
decomposition of the polymer. Alternatively, the flame retardant or
ignition resistance chemicals may decompose or sublime upon heating
to release large amounts of nonflammable vapors which exclude
oxygen from the flame.
[0015] A need exists for a cotton fiber that is inherently flame
and/or ignition resistant such that fabric made from these fiber
complies with flammability and safety regulations without
application of harsh chemicals, or with application of reduced
amounts of chemical compared to fabric made from untreated cotton
fibers.
[0016] A need also exists for a cotton fiber that is made
inherently flame and/or ignition resistance such that fabric made
from these fibers complies with flammability safety regulations by
having a ignition resistant wax sheath without application of flame
retardant chemicals, or with application of reduced amounts of such
chemical compared to fabric made from untreated cotton fiber.
SUMMARY OF THE INVENTION
[0017] The present invention comprises a major departure from the
present state of the art by discovering that bi-regional cotton
fiber which has a wax sheath unexpectedly has flame retardant
and/or ignition resistant properties, even after being dyed under
low temperature and alkaline conditions.
[0018] One embodiment of the invention is directed to bi-regional
cotton fiber comprised of a cellulosic center and an outer surface
comprised of a wax. Preferably the bi-regional fiber is bleached
and preferably bleached with chlorine, ozone, peroxide,
hypochlorite or a combination thereof. Preferably the wax comprises
at least 0.4 percent by weight of said fiber, more preferably the
wax comprises from about 0.4 percent to about 25 percent by weight
of said fiber, and more preferably from about 14 percent to about
16 percent by weight of said fiber. Preferably the wax comprises is
a natural wax, a synthetic wax, an emulsified wax or a mixture
thereof, wherein the natural wax is preferably a cotton wax, a
jojoba wax, a soy wax, a carnauba wax, or a combination thereof,
and also preferably the wax has a melting point temperature of
about 70.degree. C. or greater or about 90.degree. C. or greater.
Preferably the fibers have at least 10 percent greater tensile
strength as compared to natural cotton fibers, and more preferably
at least 20 percent greater tensile strength as compared to natural
cotton fibers. Also preferably the bi-regional fibers further
comprise a saponified acid or derivative thereof on the outer
surface of the fiber. Preferably the saponified acid or derivative
thereof comprises lauric acid, myristic acid, palmitic acid,
stearic acid, oleic acid or combinations thereof. Preferably the
bi-regional fiber is fire retardant and/or ignition resistant
and/or meets or exceeds a vertical burn test conducted according to
FAR 25.853(b). Preferably, the fire retardant and/or ignition
resistant bi-regional fiber contains no harmful chemicals such as
organohalogens. Also preferably, the bi-regional fiber has reduced
water absorption as compared to a natural cotton fiber.
[0019] Another embodiment of the invention is directed to materials
comprised of a plurality of the bi-regional fibers of the
invention. Preferably the materials are fire retardant and/or
ignition resistant and, also preferably, the materials have reduced
water absorption as compared to a natural cotton fiber. Preferably
the materials have a wrinkle resistance greater than conventional
cotton.
[0020] Another embodiment of the invention comprises fibers and/or
materials of the invention further comprising additional fibers
such as, for example, natural fibers, synthetic fibers,
carbonaceous fibers, and combinations thereof. Preferably the
synthetic fibers comprise polyester and the carbonaceous fibers
comprise flexible bi-regional carbonaceous fibers. Also preferably,
the synthetic fibers comprise about 50 to about 90 percent
polyester and about 10 to about 50 percent bi-regional fibers.
[0021] Another embodiment of the invention comprises apparel
comprised of materials and/or fibers of the invention as for
infants, toddlers, children and adults. Preferably the apparel
comprises shirts, socks, pants, sweaters, hats, coats,
undergarments, sportswear, skirts, sweats, scarves, gators,
dresses, tops, blankets, and designs and combinations thereof. Also
preferably, the apparel is suitable for wear in environments
wherein conditions are greater than and/or less than body
temperature including for sports activities such as for example,
snow sports, hiking in mountains, jungles and deserts, and rock and
mountain climbing. At least in part due to immediate transfer of
water and water vapor through the material, apparel of the
invention is suitable for wear in both ambient and extremes of
temperature environments.
[0022] Another embodiment of the invention comprises methods for
manufacture of a fiber comprising: bleaching a cotton fiber; and
applying a wax to the fiber and, also preferably, no wash step is
performed after bleaching and before application of the wax.
Preferably bleaching comprises treating the fiber with chlorine,
ozone, peroxide, hypochlorite or a combination thereof and, also
preferably, bleaching is performed at about 40.degree. C. or less,
or at room or ambient temperature and at a pH of between about 6
and about 8. Preferably the fibers comprise ignition resistance
without added harmful chemicals. Preferably the manufacturing
combines fibers of the invention with polyester fibers and also
preferably, the polyester fibers are treated with a solution of a
hydrolyzed partial condensation of trimethoxy methyl silane.
[0023] Other embodiments and advantages of the invention are set
forth in part in the description, which follows, and in part, may
be obvious from this description, or may be learned from the
practice of the invention.
DESCRIPTION OF THE INVENTION
[0024] Cotton fabric can be made flame retardant or ignition
resistant by treating with certain chemicals that change or
interrupt pyrolysis (e.g., organohalogens, compounds containing
bromine or chlorine). These treatments typically involve harsh
chemicals which are unfriendly to the environment and linked to
health problems. Many of these compounds are known to be harmful
and may be carcinogenic and/or toxic. In addition, cotton fabrics
so treated lack the performance properties and consumer appeal of
pure cotton.
[0025] It has been surprisingly discovered that cotton fibers can
be made fire retardant and/or ignition resistant without the need
for harsh or harmful chemical treatments by creating hi-regional
fibers of the invention. These bi-regional fibers of the invention
preferably contain substantially reduced or no harsh and/or harmful
chemicals. Bi-regional cotton fibers of the invention are made from
regular, ecru (i.e., raw) or unbleached cotton either in the yarn
or in fabric form. The resultant bi-regional cotton that preferable
has at least about a ten percent or more greater tensile strength
as compared to untreated or conventionally treated cotton fibers,
more preferable about 20 percent or greater, more preferably about
30 percent or greater, more preferably about 50 percent or greater.
Fibers of the invention with increased tensile strength as compared
to regular process cotton using high temperature and high
alkalinity, also have surprisingly superior moisture handling
capabilities and wrinkle resistance as compared to traditional
cotton. Superior moisture handling capability means that the fiber
or fiber assembly is less absorbent of water.
[0026] Bi-regional cotton fibers of the invention are preferably
ignition resistant and flame retardant and pass the 45 degree angle
flame impingement test as prescribed for children sleepwear in the
United States. The bi-regional cotton has no harsh chemicals in
contact with the infant skin and requires no additional ignition
resistance or flame retardant treatment such as that required by
traditional cotton. The chemical treatments conventionally required
for flame and ignition resistance normally used in traditional
cotton have been linked to sudden infant death syndrome and low
IQs. Further, the cost of making the bi-regional cotton is
competitive with polyester and should restore this material as the
material of choice for newborn, infant and children's clothing.
[0027] The preferred embodiment of bi-regional cotton retains the
natural waxes and oils of raw cotton and requires no additional
finishes or lubricants and has superior handling compared with
traditional cotton fabrics. The bi-regional cotton dyes in a more
uniform manner than traditional processed cotton, such as the Kier
process, and has far superior comfort properties.
[0028] The intended consequence of the Kier process, which is the
standard processing of cotton, is that it removes all of the wax
from the cotton fibers. A low alkaline and low temperature process
has been developed that does not remove the waxes. It was
surprisingly discovered that an unexpected result of such a
treatment allows the wax to either migrate to the surface of the
cotton fiber or does not remove the surface wax thereby markedly
increasing the ignition resistance of the final cotton fabric. Also
the method with mild heating migrates the wax to the surface
forming the bi-regional fiber. Other properties such as an enhanced
hand feel and smoothness of the fiber assemblies, is also obtained.
The process requires that all treatments must be performed at a low
temperature and alkalinity so as not to result in unintended
saponification which could solubilize and result in removal of the
wax.
[0029] Dye-ability is an important asset for any textile fiber.
Cotton is fortunate that it can be colored by numerous different
dyeing classes. Unfortunately, many of these such as vat, sulfur
and/or naphthol, are performed employing high alkaline conditions.
The choice of dye class varies in the fastness properties they are
able to impart to the finished dyed cotton such as light fastness,
wash fastness, fastness to perspiration and the like. To achieve
uniformity of dyeing, the cotton is first prepared so that a
uniform uptake and leveling of the applied dyestuff is achieved.
The normal preparation step involves a Kier type treatment followed
by bleaching to remove natural colored impurities. The most
desirable dyeing conditions which insure survivability of the
residual wax is a low temperature/low alkali reactive dyeing
process.
[0030] Accordingly, the normally employed Kier/bleach process can
be replaced with either a low temperature-peroxide/catalyst or low
alkalinity hypochlorite process. These bleaching steps employ an
oxidative rather than a high heat/alkalinity process to remove
cotton impurities. The result is a process that retains essentially
all of the waxy composition of the cotton fiber. In addition, the
wax appears un-expectantly to either migrate to the surface of the
fiber or remain on the surface and is not removed by these
oxidative processes. This process creates a wax layer on the outer
surface of the cotton, thereby causing fibers to be bi-regional.
This surface wax contributes to improving the ignition resistance
of the fabric.
[0031] When using peroxide bleaching, the bleach temperature
preferably does not exceed 60.degree. C. Normal peroxide processes
are done at the boil or employ a steaming step, for example, by
saturated steam at 100.degree. C. or greater for continuous
operations. Instead of employing a high alkalinity to stabilize the
peroxide bath, only a 2 g/l caustic solution is employed along with
a complex blend of low foaming surfactants, a stabilizer (e.g.,
Crosprep HES), and a catalyst that is active at the lower
temperature (e.g., Crosprep CAT) is employed. Any remaining
peroxide is neutralized employing a non alkaline agent (e.g.,
Croszyme PEK). Crosprep and Croszyme can be obtained commercially
from Eurodye-CTC S.A., Jodoigne, Belgium.
[0032] If chlorine bleach is used, preferably 1 g/l Cl.sub.2 is
employed in the bleach bath to prevent over bleaching and pH is
maintained at 7.5 to 8.0. Preferably sodium carbonate is used as
buffering the bleach bath instead of caustic soda. This reduces the
potential saponification of the wax. At lower pH, the bleaching
action increases. For cotton fabrics with high natural color
content, the temperature can also be increased, but should
preferably not exceed 40.degree. C. Preferably the temperature is
40.degree. C. or below, more preferably 30.degree. C. or below,
more preferably 25.degree. C. or below, and more preferably at
about ambient or room temperature. In such cases it is preferred to
employ the weaker (1 g/l Cl.sub.2) bleach solution at a higher
temperature than to use stronger bleach solutions at lower
temperatures. This is because the activity of the OCl.sup.-ion
responsible for the bleaching is temperature dependent (see, R. H.
Peters, Textile Chemistry Vol. II, Elsevier, New York 1967). Normal
Chlorine bleaching processes, pads the bleach solution onto wet
goods such as fabric directly from the kier process. In the process
of the invention, the bleach is applied directly to the dry cloth
and problems associated with bleaching uniformity in the fabric are
reduced. The bleach solution can be applied by any of the
application processes such as, for example, spraying, foaming,
padding or the like.
[0033] Acidic products are produced as the oxidation process
proceeds which reduce the normal alkalinity present. Ordinary
bleaching with chlorine requires additional alkali to insure
neutralization of the HCl which is formed during bleaching. This
results in excessive alkali being present after bleaching which is
removed usually by a post treatment with acetic acid. Another
advantage of this bi-regional cotton process is that an acetic acid
wash step, to remove residual alkali, can usually be omitted since
very little residual base should be present after the bleaching
process. This saves processing time and also expense. The pH of the
fabric will be sufficiently low after rinsing so as not to
interfere with subsequent dyeing processes.
[0034] In a continuous process, J boxes can be employed to store
the padded cloth but the dwell time preferably does not exceed 20
minutes. As with any chlorine bleach methods any residual chlorine
is preferably neutralized with either sodium thiosulfate or sodium
bisulfite antichlor.
[0035] Bleaching with bromine is faster than with chlorine but
generally the method is not as cost effective as with chlorine.
Small amounts (e.g., 1-2 percent of bromine on weight of chlorine
content) added to the chlorine bleach solutions also measurably
improves bleaching efficiency (see, R. H. Peters, Textile
Chemistry, Vol II, Elsevier, New York, 1967).
[0036] Other cellulosic fibers that do not have a natural wax
content similar to bi-regional cotton of the invention are
preferably treated with a topical wax and receive the same or
similar ignition resistance. These other cellulosic fibers include
the Rayon's, Linen, although non-prepared Linen has a natural wax
content of 0.5-2.0 percent (having a melting point of about
62.degree. C.) as well as blends. In these cases it is possible to
subsequently treat the cellulose containing fabrics with a number
of natural wax emulsions. The temperatures of drying will allow the
emulsified wax to evenly distribute itself and become affixed on
the fiber surface to achieve the bi-regional structure and the same
ignition resistance as the so treated cotton.
[0037] This technique can also be employed to treat cotton fabrics
processed in the classical fashion such as, for example, by the
Kier process which removes virtually all natural wax. A number of
high melting petroleum based waxes are also known and are available
that will also have utility as substitutes for the natural waxes.
Preferred waxes include, but are not limited to carnauba, bees wax,
palm, soy, candelilla, jojoba, wool waxes, and the like and
combinations thereof (see Table 2). Blends of natural waxes and
petroleum based waxes may also be utilized. Cotton having different
processing histories can be treated with these types of wax blends
and are included within the scope of the invention.
TABLE-US-00002 TABLE 2 Melting Points of Some Natural Waxes
(.degree. C.) Bees Wax 62-65 Palm 58-60 Carnauba 81-86 Candelilla
68-73 Soy (high melting type) ~82 Jojoba (high melting type) ~70
Cotton ~77
[0038] In addition, blends of cellulosic fibers will benefit from a
post application of an emulsified wax or combination of waxes. The
application of the saponified acid derivatives such as, for
example, lauric, myristic, palmitic, stearic, oleic and
combinations thereof provide ignition resistance to treated
fabrics. These products are removable in a conventional laundry
cycle, but are preferably useful for fabrics that are not intended
to be laundered.
[0039] Once the fabric has been bleached it is preferably dyed. The
dyeing method of choice is with reactive dyes that can be dyed at
temperatures not exceeding 60.degree. C. and at low alkalinity. The
dyes form a covalent dye with active hydrogen on the cotton fiber.
The dye is preferably salted on with high concentrations of sodium
chloride. The amount employed depends upon the dye level required
to produce the required shade. Table 3 provides levels of salt to
employ and concentration of alkali. A preferred alkali is soda ash
and can be employed to achieve the fixation of the dye. Once the
dye reaches the desired equilibrium, for example the proper shade,
2 gpl soda ash is added to fix the dye within the fibers. This
level of alkalinity does not result in saponification of the
surface wax. Dyeing is continued at the 60.degree. C. until
fixation is assured.
TABLE-US-00003 TABLE 3 Salt and Alkali Concentrations at Specific
Dye Add-ons Percent Dye on Fabric NaCl (gpl) Soda Ash (gpl)
<0.50 20 10 0.50-1.0 35 15 1.0-2.0 50 20 2.0-4.0 60 20 >4.0
80 20
[0040] One disadvantage of cotton fabric is that the material
ignites easily and burns rapidly. The flammability of a fabric is
dependent upon its composition (see, Mehta, R. D., Textile Research
Journal 44(10): 825-826 (1974)). The extent of flame and glow
resistance of a fabric increases as the carboxyl and metal contents
of the fabric increased. In view of the danger posed by flammable
textiles in general, the government has promulgated consumer safety
regulations for textiles including safety standards for carpets and
rugs, mattresses and children's sleepwear. The flammability
characteristics of textiles used to manufacture upholstery found in
motor vehicles and airplanes are also regulated.
[0041] In one embodiment, the invention comprises a bi-regional
cotton fiber, fiber assembly or fabric. The cotton or cellulose
(e.g., cellulosic) core fiber comprises the fiber core at least 70
percent of the fiber by weight and have a wax sheath or coating
(also referred to as the outer core) comprising at least 2/10 of a
percent to 25 percent of the whole cotton fiber by weight. The wax
coating may be high temperature (high melting point) wax which is
preferably a melting point at or above 70.degree. C. Alternatively,
the wax coating may be of lower temperature melting wax. This
bi-regional fiber contains a unique blend of cellulose with wax.
The wax may be a naturally occurring wax from the processed cotton
ball or it may be an emulsified wax added to the fiber surface.
This wax can be added to the fibers after a low temperature
processing, preferably less than 70.degree. C. In another
embodiment, the wax may be coated on the fibers after standard
process such as, for example, Kier processing.
[0042] In one embodiment the wax may constitute about 0.4 to 1
percent by weight of the cotton fiber. In another embodiment the
wax may constitute about 10 to 25 percent by weight of the cotton
fiber. In another embodiment, the wax may comprise about 14 to 16
percent of the cotton fiber by weight.
[0043] The fibers or woven fabric made from such fibers become an
ignition resistant fiber. This is attributed to the high wax
content of the fibers coating the exterior (see Example 4). The
fibers or fabric preferably exhibit a smooth, silky texture and
enhanced moisture (water wetting) resistance as a result of the wax
coating. Fiber of the invention is preferably stronger than
standard cotton fibers because of the milder processing conditions
employed, such as, for example, lower processing temperature. The
cotton of the invention preferably possesses flame resistance
(flame retardant and/or ignition resistance) to meet flammability
safety regulation without application chemical additives or with
application of reduced amounts of flame resistant chemicals.
[0044] It has also been surprisingly discovered that blends of the
cotton fiber of the invention can be made with flexible bi-regional
carbonaceous fibers (BRCF) as described in U.S. Pat. No. 5,700,573.
Blends comprising preferably from 10 to 90 percent of the cotton
fibers of the invention with the balance of the fibers being BRCF.
Preferably untreated cellulose core fiber comprises at least 70
percent of the fiber by weight and the wax sheath comprises from at
least 0.2 percent to 15 percent of the cotton fiber by weight.
These blends are made into knitted fabrics having densities ranging
preferably from 3 to 15 ounces per square yard are ignition
resistant and have superior cooling properties due to the micro
evaporative cooling nature of both the cotton fibers of the
invention and the BRCF The ignition resistance of the fabric
blends, utilizing the BRCF and/or the cotton fibers of the
invention, are determined following the test procedure set forth in
14 C.F.R. .sctn.25.853(b). Samples preferably pass an FR test and
exhibit superior thermal resistance values with clo thermal
resistance values ranging from 2.6 to 3.6.
[0045] The low-energy room temperature method of cleaning and
bleaching leaves the natural wax sheath around the cotton resulting
in significant energy savings and carbon dioxide emission
reductions, in comparison to the traditional high pH effluent
process. For each metric ton of cotton, the process of the
invention produces smarter cotton which reduces CO.sub.2 emissions
by 560 pounds and reduces energy consumption by 906 kWh. When this
process is widely adopted in the USA, CO.sub.2 emissions can be
reduced by up 4.43 MM tons and up to 14 GWh. Besides the
significant positive environmental impact, the superior smarter
cotton is up to 30 percent stronger, shows inherent reduced
ignitability, enhanced moisture wicking, stain and easy care
properties. Clothing and articles made from the smarter cotton are
environmentally green and made from a sustainable material compared
to synthetic materials. For example, 5.7 million metric tons of
cotton will save 906 kWh (kilowatt hours) and 506 lbs. per metric
ton. Two forms of smarter cotton are released to the market.
[0046] One form of the smarter cotton of the invention that
comprises premium long staple combed cotton is referred to herein
as NuGard. NuGard is a form of cotton fibers of the invention that
has significantly improved properties compared to conventional
forms of cotton. NuGard maximizes the wearer's comfort in addition
to reduced ignitability without adding flame resistant chemicals.
Articles composed of NuGard are extremely cool in warm weather,
have a naturally ultimate soft silky hand, and show reduced
tendency to staining and wrinkling as compared with conventionally
treated cotton and polyester. Sweat rings with Nugard are not
present thanks to its micro-evaporation power. The natural wax
repels instant spills, facilitates vapor transport inside-out
keeping the wearer cool and dry to the skin. Instead of
compromising performances, the sustainable lower energy process is
in synergy with enhanced comfort, quick dry laundry and easy care
conditions. Bi-regional cotton fibers of the invention including
Nugard cotton can be made into most any apparel including apparel
for infants, toddlers, children and adults such as, for example,
shirts, socks, pants, sweaters, hats, scarves, gators, sweats,
coats, undergarments, sportswear, skirts, dresses, tops, and
blankets. Other embodiments of the invention comprise materials
composed of fibers of the invention combined with additional fibers
and other materials, such as, for example, leathers, metals,
plastics and other polymers in creating most any design and style
of clothing and apparel. Workhorse cotton fabric products such as
underwear, denim jeans, sheeting, bedding, children's clothing, and
the like can be referred to as DuraGard products.
[0047] Treated cotton, because of the wax coated surfaces has the
following preferred characteristics: (i) increased staining
resistance and improved soil release characteristics; (ii) natural
softness and hand; (iii) natural water repellency providing greater
dry sleeping comfort; (iv) when blended with diamondown will
provide superior thermal comfort by blocking 91 percent of radiant
heat loss; (v) enhanced fabric wick ability; and (vi) less problems
associated with dyeing. Fabrics manufactured employing the so
treated cotton will experience a greater degree of polymerization
(DP) in the final fabric because of the less harsh preparation and
process treatments normally employed. As a consequence, in a
comparison of water-repelling cotton of one embodiment of the
invention shows water beading on and not within the fabric, whereas
traditional cotton shows water being absorbed by the fabric. Also
because of the lower processing damage, the fabrics possess
increased tenacity (about 14 percent) and elongations (about 14
percent). In addition, the milder processing reduces the associated
energy costs (about 20 percent minimum) as well as lower water
consumption and waste water treatment requirements. There is also a
lowering of the CO.sub.2 emissions (about 17 percent minimum)
because the processes are preferably accomplished at lower
temperatures.
[0048] Forms of the invention herein shown and described are to be
taken as the presently preferred embodiments. Various changes may
be made in the shape, size and arrangement of components or
adjustments made in the steps of the method without departing from
the scope of this invention. For example, equivalent elements may
be substituted for those illustrated and described herein and
certain features of the invention maybe utilized independently of
the use of other features, all as would be apparent to one skilled
in the art after having the benefit of this description of the
invention.
[0049] The term "ignition resistant" as used herein refers to
fibers or fiber assemblies that satisfactorily pass the (a) FAR
25.853(b) Flammability of Aircraft Seat Cushions, or (b)
flammability test or the 45 degree angle flame impingement test (16
CFR 1610, Standard for the Flammability of Clothing Textiles).
[0050] The term "fiber assembly" used herein applies to a
multiplicity of fibers that are in the form of a yarn, a wool like
fluff, batt, mat, web or felt, and comprising a formed sheet,
screen or panel, a braided, knitted or woven cloth or fabric, or
the like.
[0051] The term "cohesion" or "cohesiveness" used herein, applies
to the force which holds fibers together, especially during yarn
manufacture and is a function of the type and amount of lubricant
used, the fiber crimp and twist.
[0052] The term "Kier process" as used herein refers to the prior
art standard processing of treating raw cotton by boiling the
cotton to remove oils and waxes by saponification from the primary
cellulose polymer substrate.
[0053] The term "high temperature high alkalinity processed cotton"
means cotton processed by the Kier process or similar processes
conducted at temperatures of near 100.degree. C.
[0054] All percentages disclosed herein are "percent by weight"
unless otherwise specified.
[0055] The following examples illustrate embodiments of the
invention, but should not be viewed as limiting the scope of the
invention.
Example 1
Bleaching with Peroxide
[0056] To the cotton fabric is added a solution containing 3-4 gpl,
peroxide (50%), 2 gpl caustic soda (NaOH), and 1 gpl of a low
foaming surfactant/stabilizer (such as Crosprep HES) at a 10/1
fabric to liquor ratio. The fabric and solution is heated to
60.degree. C. over 15 minutes. One gpl of a catalyst suitable for
low temperature peroxide bleaching (such as Crosprep CAT) is added
and the fabric heated in this mixture at the 60.degree. C.
temperature for 45 minutes followed by draining and refilling.
Acetic acid is added over 5 minutes until the pH stabilizes to
6.5-7.0. The fabric is then treated for 10 minutes with a
stabilized liquid catalase (such as Croszyme PEK) to neutralize any
residual peroxide. The fabric is rinsed, drained and dried.
[0057] Cotton yarns can be bleached effectively in a pressure
dyeing machine. The pH of the bleach liquors can be easily adjusted
to control the pH with soda ash. The bleach solution is
automatically programmed to give alternate inside out and outside
in of the yarn package in to insure bleach uniformity. The acetic
acid rinse can be controlled to keep the cloth near neutral. This
is followed by treatment with the catalase to remove residual
peroxide and a final rinse.
Bleaching with Oxygen
[0058] The advantages of employing package dyeing equipment for the
novel low temperature, low alkali bleaching system is essentially
the same as that cited for the chlorine bleach systems via a
finishing plant operation. During this dyeing process, pH control
is maintained for the bleach system. The pH is continuously
monitored through the add system of the package dyeing machine.
Bleaching with Chlorine
[0059] The fabric is padded to 100 percent wet pick up in a
solution containing 0.2 g/l wetting agent and 1 gpl chlorine bleach
at a pH of 7.5-8.0 and stored in a J Box for 20 minutes at room
temperature. For highly discolored fabrics the temperature may be
increased but may not exceed 40.degree. C. For pH adjustments, soda
ash is preferred because of its buffering effect and so the cloth
will not need an acetic acid rinse to obtain a final pH of 6.8-7.2.
An antichlor treatment with sodium bisulfite or sodium thiosulfate
to remove any unreacted chlorine completes the bleaching
process.
[0060] Fibers derived from raw cotton fiber (ecru) are bleached at
less than 70.degree. C., preferably at ambient or room temperature,
with a bleaching solution comprising an OX.sup.- system, where X is
a halogen and where the pH is 6.5 to 8.
Dyeing
[0061] The dye bath is set with the proper concentration of dye on
the fabric, 1 gpl of antifoam such as Croscolor SLR New, 1 gpl of
Croscour HP-JS and the salt concentration from Table 3. The
temperature is raised to 60.degree. C. and dye for 20 minutes. Soda
ash (see Table 3) is added and dyeing continued for 40 additional
minutes. The bath is dropped and the fabric is given a hot
(60.degree. C.) rinse containing 1 gpl acetic acid. The bath is
dropped and the fabric soaped 10 minutes at 60.degree. C. with 1
gpl Croscolor BCSR followed by a hot (60.degree. C.) rinse for 10
minutes and a cold rinse (20.degree. C.) for 10 minutes. Treatment
of cellulose containing fabrics continues after a standard
preparation treatment.
[0062] Another method of chlorine bleaching is to employ package
dyeing equipment. This method offers considerable advantages over
continuous bleaching in a finishing plant. The pH of the process is
continuously monitored via the add tank and corrections can be made
while running. After the antichlor treatment the yarn packages do
not need to be dried but the dyeing operation can be started
immediately. This bleach method can be employed on small runs in
order to make and test product changes, for example, in the color
line or for product modifications. Further, this method provides
better shrinkage control of the yarns since normal shrinkage will
have occurred during the package bleaching/dyeing process.
Example 2
[0063] A desized and bleached cotton print cloth (Testfabrics style
400 weighing 3.03 osy (oz/yd.sup.2)) was treated at 100 percent wet
pickup with a solution of a 0.75 percent owf (on weight of fabric)
emulsified candelilla wax, and 0.1 percent nonionic wetting agent.
After drying, the fabric passed the 45.degree. C. flammability
test, (16 C.F.R. .sctn.1610, standard for the flammability of
clothing textiles) and did not ignite even after a 4 second flame
impingement.
Example 3
[0064] An army carded cotton sateen which had been desized and
bleached (Testfabrics style 428 weighing 6.93 osy, and a bleached,
mercerized, and carded cotton broad cloth (Testfabrics' style 453,
weighing 3.53 osy) and a cotton sheeting (Testfabrics' style 493,
weighing 4.45 osy) gave the same results (passed the 45.degree. C.
flammability test) after treating in the fabrics in the manner
described above, (treated at 100 percent wet pickup with a solution
of a 0.75 percent owf (on weight of fabric) emulsified candelilla
wax, and 0.1 percent nonionic wetting agent).
Example 4
[0065] A spun Viscose challis (ISO-105/F02, Testfabrics style 266,
weighing 4.07 osy) treated as above, did not ignite even after a
four second flame impingement.
Example 5
[0066] A Cotton/Linen 56/44 blended fabric (Testfabrics' style
L5040, weighing 6.4 osy) treated as above did not ignite even after
a 4 second flame impingement. The same results were obtained when
bees wax was substituted for the candelilla wax. The same results
were obtained when a 50/50 emulsified blend of Jojoba and Carnauba
was employed.
[0067] The desized and bleach print cloth (Testfabrics' style 400)
cited above was treated with 1.0 percent blend (50/50 w/w) mixture
of oleic and stearic acid at 75 percent wet pickup. After drying,
fabric did not ignite even after a 4 second flame impingement. The
ignition resistance protection did not occur after the fabric was
laundered to remove the acid blend.
Example 6
[0068] The non-flammability and ignition resistance of the
bi-regional cotton fibers of the disclosure is determined following
the test procedure set forth in 14 C.F.R. .sctn.25.853(b). The test
is performed as follows:
[0069] A minimum of three 1 inch.times.6 inch.times.6 inch (2.54
cm.times.15.24 cm.times.15.24 cm) specimens (derived from a batting
of the bi-regional whole cotton fibers as prepared above. The
specimens are conditioned by maintaining them in a conditioning
room maintained at a temperature of 70.degree. C..+-.3.degree. C.
and 5 percent relative humidity for 24 hours preceding the
test.
[0070] Each specimen is supported vertically and exposed to a
Bunsen or Turill burner with a nominal I.D. tube of 1.5 inches (3.8
cm) in height. The minimum flame temperature is measured by a
calibrated thermocouple pyrometer in the center of the flame and is
1550.degree. F. (843.degree. C.). The lower edge of the specimen is
0.75 inch (1.91 cm) above the top edge of the burner. The flame is
applied to the cluster line of the lower edge of the specimens for
12 seconds and then removed.
[0071] Pursuant to the test, the material is self-extinguishing.
The average burn length does not exceed 8 inch (20.32 cm), the
average after flame does not exceed 15 seconds and flaming
drippings did not continue to burn for more than 5 seconds after
falling to the burn test cabinet floor.
Example 7
[0072] Ozone has been found to be effective in the de-colorization
of dyes such as indigo (see Wasinger/Hall U.S. Pat. Nos. 5,313,811,
5,366,510 and 5,531,796). Ozone is also effective as a bleaching
agent on desized and prepared goods in a finishing plant operation
(see, Wasinger/Hall U.S. Pat. No. 5,376,143). Ozone may not have
been used as a bleaching agent on raw cotton goods because the
usual finishing plant preparation procedures involve the removal of
the wax.
[0073] Raw cotton yarn can be bleached in a package dyeing machine
using ozone without removal of the cotton wax to a degree of
whiteness ranging from 75-85 (AATCC Method 110 "American
Association of Textile Chemists and Colorists") depending upon the
time, ozone concentration and water temperature of the treatment.
The so bleached goods were found to have retained almost all of its
initial tensile strength along with an increase in the wet-ability
of the goods without any measurable wax removal. After treatment
the package is ready for dyeing.
[0074] In a one pound Morton sample package dye machine, is added
deionized water (pH 6.9-7.2 and 15-18.degree. C.), 0.10 gpl
Tergitol wetting agent owb that was circulate in and out through
the yarn package for 5 minutes. Ozone from a ClearWater Tech (Model
CD2000P) generator with a dry air flow and at a pressure of 10 psi
was added continuously over 30-60 minutes depending upon the level
of whiteness desired. The flow cycle was 5 minutes on the outside
in and 5 minutes on inside out. After rinsing (two in-out cycles)
twice with deionized water, the package was dried by the usual
methods. If dyeing is to occur, the packages are already prepared
and do not need to be pre-dried prior to the dyeing. Since the
packages are wound in a loose state, normal shrinkage occurs and
hence the shrinkage in the final garment is mitigated. Another
advantage is that small lots can be evaluated for color and other
properties without the need for long runs to produce enough fabric
for full finishing machinery trials.
[0075] Ozone creates hydroxyl (OH.sup.-) radicals which although
they are short lived at elevated temperatures are sufficiently
stabile in cold water to effectively facilitate in the bleaching
along with the ozone itself.
[0076] Additional advantages of this bleach system include the
absence of BOD (biochemical oxygen demand) in the effluent; any
bacteria or fungi in the cotton goods are also destroyed.
[0077] The use of the package machine is also useful for bleaching
employing essentially the same low temperature process that is
described for fabric bleaching. The advantage of this process is
that the yarn is now ready for dyeing without a pre-drying step
employed with fabric bleaching.
[0078] Other embodiments and uses of the invention will be apparent
to those skilled in the art from consideration of the specification
and practice of the invention disclosed herein. All references
cited herein, including all publications, and all U.S. and foreign
patents and patent applications are specifically and entirely
incorporated by reference. The term comprising, where ever used, is
intended to include the terms consisting and consisting essentially
of. Furthermore, the terms comprising, including, and containing
are not intended to be limiting. It is intended that the
specification and examples be considered exemplary only with the
true scope and spirit of the invention indicated by the following
claims.
* * * * *