U.S. patent application number 14/071432 was filed with the patent office on 2015-05-07 for novel ignition resistant cotton fiber, articles made from ignition resistant cotton fibers, and methods of manufacture.
The applicant listed for this patent is Carbtex Technology, Inc.. Invention is credited to David Hall, Francis McCullough.
Application Number | 20150121628 14/071432 |
Document ID | / |
Family ID | 53005848 |
Filed Date | 2015-05-07 |
United States Patent
Application |
20150121628 |
Kind Code |
A1 |
McCullough; Francis ; et
al. |
May 7, 2015 |
NOVEL IGNITION RESISTANT COTTON FIBER, ARTICLES MADE FROM IGNITION
RESISTANT COTTON FIBERS, AND METHODS OF MANUFACTURE
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, e.g., Keir process which may
include bleach at approximately 100.degree. C.. and the wax
subsequently added at a temperature sufficient to disperse the wax
over the fibers. The fibers are ignition resistant as measured by
industry standard tests, e.g., FAR 25.853(b) or 14 CFR 25.853(b).
The wax may comprise less than 1 percent to 25 percent 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 subject of U.S. Pat. No.
5,700,573.
Inventors: |
McCullough; Francis;
(Houston, TX) ; Hall; David; (Auburn, AL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Carbtex Technology, Inc. |
Houston |
TX |
US |
|
|
Family ID: |
53005848 |
Appl. No.: |
14/071432 |
Filed: |
November 4, 2013 |
Current U.S.
Class: |
8/108.1 ;
428/221; 428/375; 8/111 |
Current CPC
Class: |
D06L 4/13 20170101; D06M
13/224 20130101; Y10T 428/2933 20150115; D06L 4/12 20170101; D06L
4/24 20170101; D06M 2200/30 20130101; D06M 2101/06 20130101; Y10T
428/249921 20150401 |
Class at
Publication: |
8/108.1 ;
428/375; 428/221; 8/111 |
International
Class: |
D06M 13/224 20060101
D06M013/224; D06L 3/06 20060101 D06L003/06; D06L 3/02 20060101
D06L003/02; D06L 3/08 20060101 D06L003/08 |
Claims
1. An ignition resistant fiber or assembly of fibers comprising a
fiber having a cellulosic center and an outer region or surface of
a wax wherein the wax comprises 0.4 to 1.0 or greater percentage by
weight of fiber.
2. The fiber or assembly of fibers of claim 1 further comprising an
outer region of a high temperature melting wax.
3. The fiber or assembly of fiber of claim 2 further comprising an
outer region of wax having a melting point of 70.degree. C. or
higher.
4. The fiber or assembly of fibers of claim 1 further comprising a
cellulosic center of cotton fiber.
5. The fiber or assembly of fibers of claim 1, wherein said wax is
a natural wax.
6. The fiber of claim 1 or assembly of fibers, wherein the said wax
is a emulsified wax or mixtures of emulsified waxes.
7. The fiber or assembly of fibers of claim 1, wherein said wax is
a mixture of natural and emulsified waxes.
8. The fiber or assembly of fibers of claim 1, wherein said wax is
cotton wax.
9. The fiber or assembly of fibers of claim 1 wherein said wax is
jojoba wax.
10. The fiber or assembly of fibers of claim 1 wherein said wax is
high melting soy wax.
11. The fiber or assembly of fibers of claim 1 wherein said wax is
carnuba wax
12. The fiber or assembly of fibers of claim 2 wherein the wax is
selected form a group consisting of natural wax, emulsified wax, a
mixture of emulsified waxes, a mixture of emulsified waxes and
natural wax, cotton wax, jojoba wax, high melting soy wax, carnuba
wax or combinations thereof.
13. The fiber or assembly of fibers comprising bi-regional cotton
of claim 1 is 10% to 20% stronger than standard high temperature
high alkalinity processed cotton.
14. The fiber or assembly of fibers of claim 1 wherein the fibers
have reduced absorption of water than high temperature high
alkalinity processed cotton.
15. The fiber or assembly of fibers of claim 1 wherein the fibers
have improved wrinkle resistance to high temperature high
alkalinity process cotton.
16. The fiber or assembly of fibers of claim 1 further comprising
applying a saponified acid derivative selected from a group
consisting of Lauric, Myristic, Palmitic, Stearic, Oleic or
combinations thereof.
17. Bi-regional cotton fibers comprising a cellulosic center and an
outer region of high temperature wax wherein the fibers pass a
standard vertical burn tests conducted according to FAR
25.853(b).
18. Bi-regional cotton fibers comprising a cellulosic center and an
outer region of a cotton wax, a natural wax, or a blend of natural
and synthetic waxes melting in the range of 58 to 87.degree. C.
wherein the fiber passes an ignition resistance test comprising: a
minimum of three battings having a dimension of 2.5 cm.times.15
cm.times.30 cm and comprised of 80% the bi-regional carbonaceous
fibers and 20% polyester fibers sprayed with a solution of a
hydrolyzed partial condensation of trimethoxy methyl silane wherein
the battings are compressed at 25 lb/in.sup.2 (1.75 Kg/cm.sup.2) at
a temperature of 260.degree. F. (127.degree. C.) into panels and
wherein the coating is comprised of 10% by weight, wherein standard
vertical burn tests according to FAR 25.853(b) are conducted,
wherein the panels are conditioned by maintaining the panels in a
conditioning room maintained at a temperature of 21.degree.
C..+-.5.degree. C. and 50%.+-.5% relative humidity for 24 hours
preceding the test, wherein each panel is supported vertically and
exposed to a Bunsen or Turill burner with a nominal I.D. tube
adjusted to give a flame of 3.8 cm in height with a minimum flame
temperature is 843.degree. C., wherein the lower edge of the panel
is 1.9 cm above the top edge of the burner, wherein the flame is
applied to the center line of the lower edge of the specimens for
12 seconds and then removed and wherein the panel self extinguishes
and average burn length does not exceed 20 cm, the average after
flame does not exceed 15 seconds and there are no flame
drippings.
19. Bi-regional cotton fibers comprising a cellulosic center and an
outer region of a cotton wax, a natural wax, or blend of natural
and synthetic waxes melting in the range of below 58.degree. C.
wherein the fiber passes an ignition resistance test comprising: a
minimum of three battings having a dimension of 2.5 cm.times.15
cm.times.30 cm and comprised of 80% the bi-regional carbonaceous
fibers and 20% polyester fibers sprayed with a solution of a
hydrolyzed partial condensation of trimethoxy methyl silane wherein
the battings are compressed at 25 lb/in.sup.2 (1.75 Kg/cm.sup.2) at
a temperature of 260.degree. F. (127.degree. C.) into panels and
wherein the coating is comprised of 10% by weight, wherein standard
vertical burn tests according to FAR 25.853(b) are conducted,
wherein the panels are conditioned by maintaining the panels in a
conditioning room maintained at a temperature of 21.degree. C.
.+-.5.degree. C. and 50%.+-.5% relative humidity for 24 hours
preceding the test, wherein each panel is supported vertically and
exposed to a Bunsen or Turill burner with a nominal I.D. tube
adjusted to give a flame of 3.8 cm in height with a minimum flame
temperature is 843.degree. C., wherein the lower edge of the panel
is 1.9 cm above the top edge of the burner, wherein the flame is
applied to the center line of the lower edge of the specimens for
12 seconds and then removed and wherein the panel self extinguishes
and average burn length does not exceed 20 cm, the average after
flame does not exceed 15 seconds and there are no flame
drippings.
20. A fabric or fiber assembly comprising bi-regional cotton fibers
comprising a cellulosic center and an outer region of a wax wherein
the fibers passes Testing Flammability of Clothing Textiles, 16 CFR
1610, comprising fabric specimens of 2 inches by 6 inches are dried
and cooled, the specimens are placed at a 45.degree. angle impinged
with a flame of 5/8 inch length for a second wherein a plain
surface fabric burn time is 3.5 seconds or more and a raised
surface fabric average burn time is 7 seconds or more.
21. An ignition resistant fiber or assembly of fibers comprising a
fiber having a cellulosic center and an outer region of a wax
wherein the wax comprises 0.4 to 25 percent of the fibers by
weight.
22. The fibers or assembly of fiber of claim 16 wherein the wax
comprises 1.0 to 15 percent of the fibers by weight.
23. The fibers or assembly of fibers of claim 16 wherein the wax
comprises 10 to 25 percent of the fibers by weight.
24. The fibers or assembly of fibers of claim 16 wherein the wax
comprises 14 to 16 percent of the fibers by weight.
25. Bi-regional cotton fiber comprising a cellulosic center and an
outer region comprising a wax coating wherein the wax comprises 0.4
percent to 1.5 percent by weight of the fiber.
26. A bi-regional fiber having a cellulosic center and an outer wax
coating bleached in a low temperature--peroxide/catalyst or low
alkalinity hypochlorite process employing an oxidative process to
remove impurities.
27. A process of making an ignition resistant cotton fiber where
said fiber is derived from an ECRU or raw cotton fiber by bleaching
fiber at less than 70.degree. C. with a bleaching solution
comprising a peroxide, peroxide catalyst, and a wetting agent.
28. A process of bleaching cotton fiber comprising a bleach
solution of 1 g/l Cl.sub.2 at a temperature not exceeding
40.degree. C.
29. A treatment process for raw cotton comprising treating the raw
cotton at a temperature below 75.degree. C. and a peroxide/catalyst
or low alkalinity hypochlorite process.
30. A process of treating raw cotton of claim 22 further comprising
omitting a post treatment acid wash step.
31. A process of making an ignition resistant cotton fiber where
said fiber is derived from an ECRU or raw cotton fiber by bleaching
fiber at less than 70.degree. C. with a bleaching solution
comprising an OX.sup.- system, where X is a halogen and where the
pH is 6.5 to 8.
32. A process of making an ignition resistant cotton fiber where
said fiber is derived from a standard bleaching process where an
outer region comprises a natural, emulsified or blend of wax that
is added subsequent to the bleaching process.
33. The process of claim 25 further comprising wax comprising a
high temperature melting wax.
34. A blended fire retardant fiber assembly comprising from 10 to
90% of bi-regional cotton fibers with BRCF fibers wherein the
blended fibers comprises fire retardant properties.
Description
FIELD OF THE INVENTION
[0001] The present disclosure relates to an ignition resistant
(flame retardant) whole cotton fiber, said whole cotton fiber
having a cellulose region at the core and an outer region of a wax
sheath or surface. The disclosure also relates to methods for the
manufacture of the ignition resistant whole cotton fiber, and to
articles made from a multiplicity of said bi-regional carbonaceous
fibers.
[0002] The untreated cellulose core fiber comprises at least 70% of
the fiber by weight and the wax sheath comprises from at least 2/10
of a percent to 15% of the cotton fiber by weight.
BACKGROUND OF THE INVENTION
[0003] 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
available for thousands of years; hence a great deal of knowledge
about its physical and chemical properties are well known. Because
of its unique chemical nature, it can be made to be fire retardant,
have wash-wear (wrinkle free), among numerous other properties. It
can be blended with other textile fibers to enhance the overall
performance of the blended fabric.
[0004] Raw cotton, i.e., unprocessed, like all vegetable matter
contains minerals, resins, gums, protein, tannins, oils and waxes,
and carbohydrates, in addition to cellulose. It normally has to be
purified in order to remove these products from the primary
cellulose polymer substrate. Most of these are removed in a "Kier"
boil process, a 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 these impurities.
The oils and waxes are saponifiable; hence are removed by this
"preparation" process. Continuous processes have been developed
which utilizes 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 % 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 *(From: Mathews' Textile Fibers, 5.sup.th ed. Wiley & Sons,
NY, 1947 p, 100)
[0005] Note that virtually all impurities are removed by Kier boil
"preparation" process treatment. Color is removed by a subsequent
bleaching process normally employing either a Peroxide or a
Hypochlorite process which removes the color to the desired degree
of whiteness. The cotton fabric is now ready for numerous
after-treatment processes such as dyeing by any of a variety of
methods, conversion to a wash-wear, flame resistant or others,
including combinations of all of the above. The patent literature
is rife with further treatments to enhance the utility of the so
treated cotton fabric (or cotton fabric blends).
[0006] The wax in the cotton fiber is not one having a single
component but is thought to have a blend of complex esters and
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 above (Kier process and
the like). 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
etc. Still, it is these wax components that survive the treatments
outlined which results in the surprise benefits of ignition
resistance cotton.
[0007] In order to reduce the inherent flammability of cotton
fabrics, cotton fiber can be combined with inherently flame
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% Vinal and 50% 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.
[0008] Alternatively, cotton fabric can be treated with flame
retardant chemicals that change or interrupt the burning process
known as pyrolysis. Cotton fabric treated with flame retardant
chemicals, however, typically lack the performance properties and
consumer appeal of pure cotton fabric. Most of these chemical
treatments involve the use of 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% Polyester.
[0009] 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.
[0010] The application of flame retardant chemicals may interrupt
pyrolysis. For example, the flame retardant 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
may decompose or sublime upon heating to release large amounts of
nonflammable vapors which exclude oxygen from the flame.
[0011] A need exists for a cotton fiber that is inherently flame
resistant such that fabric made from the fiber complies with
flammability and safety regulations without application of flame
retardant chemicals, or with application of reduced amounts of
flame retardant chemical compared to fabric made from known
untreated cotton fiber.
[0012] A need also exists for a cotton fiber that is made
inherently flame resistant such that fabric made from the fiber
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 flame
retardant chemical compared to fabric made from known untreated
cotton fiber.
DEFINITIONS
[0013] The term "whole cotton" used herein generally refers to an
ignition resistant fiber that has a cellulosic core and an outer
region of a wax containing sheath or surface.
[0014] 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 Flamability of Clothing
Textiles).
[0015] 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.
[0016] The term "cohesion" or "cohesiveness" used herein, applies
to the force which holds fibers together, especially during yarn
manufacture. It is a function of the type and amount of lubricant
used, the fiber crimp and twist.
[0017] The term "Kier process" as used herein refers to the prior
art standard processing of treating raw cotton by boiling the
cotton in order to remove products from the primary cellulose
polymer substrate. The oils and waxes are saponifiable; hence are
removed by this "preparation" process.
[0018] 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.
[0019] All percentages given herein are in "percent by weight"
unless otherwise specified.
SUMMARY OF THE INVENTION
[0020] The present invention comprises a major departure from the
present state of the art by discovering that be cotton fiber which
has a wax sheath unexpectedly has ignition resistant properties,
even after being dyed under low temperature and alkaline
conditions.
[0021] Bi-regional cotton of the invention is made from regular,
ECRU or unbleached cotton either in the yarn or in fabric form. The
resultant bi-regional cotton is 10% to 20% stronger than regular
process cotton using high temperature and high alkalinitiy and has
superior moisture handling capability and wrinkle resistance
compared to traditional cotton. Superior moisture handling
capability means that the fiber or fiber assembly is less absorbent
of water.
[0022] Most importantly, we have recently discovered that the
bi-regional cotton is inherently flame retardant and passes 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 flame retardant treatment such as that required by
traditional cotton to pass the 45.degree. angle flame impingement
test. The flame retardant treatments normally used in traditional
cotton have been linked to sudden infant death syndrome and low
IQs. 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.
[0023] 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.
[0024] The intended consequence of the Kier process, i.e., normal
or standard processing of cotton, is that it removes all of the wax
from the cotton fibers. A novel treatment has been developed which
employs a low alkaline and low temperature process that does not
remove the waxes. We have found 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 (mild heating) migrates the wax to the surface forming
the bi-regional fiber. Other properties, such as an enhanced hand
(feel) smoothness of the fiber assemblies is also obtained. The
cotton feels smoother than standard processed cotton. The process
requires that all treatments must be done at a low temperature and
alkalinity in order not to result in any unintended saponification
which will solubilize, and result in removal of the wax.
[0025] 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
& Naphthol) are done employing high alkaline conditions. The
choice of dye class will vary 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. In order to
achieve uniformity of dyeing, it is necessary to first prepare the
cotton 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.
[0026] 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 all the
cotton impurities. The result is a process which 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 it to be bi-regional.
This surface wax contributes to improving the ignition resistance
of the fabric.
[0027] When using peroxide bleaching as taught by the instant
disclosure, the bleach temperature does not exceed 60.degree. C.
Normal peroxide processes are done at the boil or employ a steaming
step, i.e., 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 (such as Crosprep HES), and a catalyst that is active at
the lower temperature (such as Crosprep CAT) is employed. Any
remaining peroxide is neutralized employing a non alkaline agent
(such as Croszyme PEK). (The Crosprep and Croszyme are obtained
from Eurodye-CTC S.A., Jodoigne, Belgium.)
[0028] If chlorine bleach is used only 1 g/l Cl.sub.2 is employed
in the bleach bath to prevent over bleaching. The pH is maintained
at 7.5 to 8.0. Sodium carbonate is better at buffering the bleach
bath than caustic soda. This also 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 never exceed
40.degree. C. In such cases it is best 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, N.Y. 1967) Normal Chlorine bleaching processes, pads
the bleach solution onto wet goods such as fabric directly from the
kier process. In the revised process subject of this disclosure,
the bleach is applied directly to the dry cloth and the problems
with bleach uniformity in the fabric is reduced. The bleach
solution can be applied by any of the application processes such as
spraying, foaming or padding or the like.
[0029] Acidic products are produced as the oxidation process
proceeds which reduces 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
must be 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 expenses. The pH
of the fabric will be sufficiently low after rinsing so as not to
interfere with subsequent dyeing processes.
[0030] In a continuous process, J boxes can be employed to store
the padded cloth but the dwell time should not exceed 20 minutes.
As with any chlorine bleach methods any residual chlorine should be
neutralized with either sodium thiosulfate or sodium bisulfite
antichlor.
[0031] Bleaching with bromine is faster than with chlorine but
generally the method is not as cost effective as with chlorine. We
have found that Small amounts (1-2% of bromine on weight of
chlorine content) added to the chlorine bleach solutions also
measurably improves bleaching efficiency. Ref: R. H. Peters,
Textile Chemistry, Vol II, Elsevier, N.Y., 1967
[0032] Other cellulosic fibers which may not have an inherent
natural wax content similar to our so treated cotton, (bi-regional
cotton) can be treated with a topical wax and receive the same
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% (having a melting point of about 62.degree. C.)
as well as their 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.
[0033] This technique can also be employed to treat cotton fabrics
that have been processed in the classical fashion i.e. Kier
process, that removed virtually all of its natural wax. Applying
any of a number of different natural waxes that include, but not
limited to carnauba, bees wax, palm, soy, candelilla, jojoba, &
wool waxes and the like. 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. These are also known and
those skilled in the art have.sub.-knowledge of methods necessary
to emulsify and apply these waxes, that will well work to achieve
the desired ignition resistant properties of the natural waxes.
Blends of natural waxes and petroleum based waxes will also have
utility for these applications. 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
[0034] From the foregoing discussion, it should be obvious to those
of ordinary skill in the art that blends of cellulosic fibers will
well benefit from a post application of an emulsified wax or
combination of waxes. In addition the application of the saponified
acid derivatives such as Lauric, Myristic, Palmitic, Stearic, Oleic
among others will provide some ignition resistance to the so
treated fabrics. These products will be removable in the laundry
cycle but might be useful for fabrics that are not intended to be
laundered.
[0035] Once the fabric has been bleached it may be 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 forms a covalent dye with an active hydrogen on the cotton
fiber. The dye must be 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 the suggested level
of salt to employ and concentration of alkali (The preferred alkali
is soda ash) that needs to be employed to achieve the fixation of
the dye. Once the dye reaches the desired equilibrium (i.e., 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 % 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
[0036] One disadvantage of cotton fabric, however, is that it
ignites easily and bums rapidly. The flammability of a fabric is
dependent upon its composition. Mehta, R. D., Textile Research
Journal 44(10): 825-826 (1974), incorporated herein by reference,
for example, found that the extent of flame and glow resistance of
a fabric increased 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 by the
government.
DETAILED DESCRIPTION OF THE INVENTION
[0037] This disclosure teaches a novel bi-regional cotton fiber or
fabric (fiber assembly) made from such fibers. The cotton or
cellulose (cellulosic) core fiber comprises the fiber core at least
70% of the fiber by weight and have a wax sheath or coating (outer
core) comprising at least 2/10 of a percent to 25% of the whole
cotton fiber by weight. The wax coating may be high temperature
(high melting point) wax, i.e., melting point at or above
70.degree. C. The wax coating may be of lower temperature melting
wax. High temperature wax is deemed to be wax with a melting point
in excess of 70.degree. C. 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 (less than 70.degree. C.). In
another embodiment, the wax may be coated on the fibers after
standard process, e.g., Kier processing.
[0038] In one embodiment the wax may constitute 10% to 25% by
weight of the cotton fiber. In another embodiment, the wax may
comprise 14% to 16% of the cotton fiber by weight.
[0039] 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 below.
The fibers or fabric also exhibit a smooth silky texture. The
fibers are also exhibit enhanced moisture (water wetting)
resistance as a result of the wax coating. The fiber is also
stronger than standard cotton fibers because of the milder
processing conditions employed, e.g., lower processing temperature.
The cotton taught by this disclosure possesses inherent flame
resistance to meet flammability safety regulation without
application chemical additives or with application of reduced
amounts of flame retardant chemicals. [0040] It was also found that
novel blends of the cotton fiber of the invention can be made with
flexible biregional fibers (BRCF) as described in U.S. Pat. No.
5,700,573 which is herein incorporated by reference with the blend
comprising from 10 to 90% of the cotton fibers of the invention
with the balance of the lands containing the flexible biregional
fibers. These blends made into knitted fabrics having densities
ranging 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 the cotton fibers of the invention, are determined
following the test procedure set forth in 14 CFR 25.853(b) which is
herein incorporated by reference. All samples pass this FR test.
The samples also exhibit superior thermal resistance values with
clo Thermal resistance value values ranging from 2.6 to 3.6.
[0041] It is to be understood that the forms of the disclosure
herein shown and described are to be taken as the presently
preferred embodiments. As already stated, 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.
[0042] While specific embodiments have been illustrated and
described, numerous modifications are possible without departing
from the spirit of the invention, and the scope of protection is
only limited by the scope of the accompanying claims.
EXAMPLE 1
Bleaching with Peroxide
[0043] 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. 1 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.
[0044] 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.
[0045] Bleaching with Chlorine
[0046] The fabric is padded to 100% 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.
[0047] The disclosure also teaches a process of making an ignition
resistant cotton fiber where said fiber is derived from an ECRU or
raw cotton fiber by bleaching fiber at less than 70.degree. C. with
a bleaching solution comprising an OX.sup.- system, where X is a
halogen and where the pH is 6.5 to 8.
[0048] Dyeing
[0049] The dyebath is set with the proper concentration of dye on
the fabric, 1 gpl of an 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 (from 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.
[0050] Treatment of Cellulose Containing Fabrics after a Standard
Preparation Treatment
EXAMPLE 2
[0051] A desized and bleached cotton print cloth (Testfabrics'
style 400 weighing 3.03 osy (oz/yd.sup.2) was treated at 100% wet
pickup with a solution of a 0.75% owf (on weight of fabric)
emulsified candelilla wax, and 0.1% nonionic wetting agent. After
drying, the fabric passed the 45.degree. flammability test, (16 CFR
1610, Standard for the Flamability of Clothing Textiles which is
incorporated herein by reference in its entirity) and did not
ignite even after a 4 second flame impingement.
EXAMPLE 3
[0052] 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' syle 493,
weighing 4.45 osy) gave the same results (passed the 45.degree.
flammability test) after treating in the fabrics in the manner
described above, (treated at 100% wet pickup with a solution of a
0.75% owf (on weight of fabric) emulsified candelilla wax, and 0.1%
nonionic wetting agent).
EXAMPLE 4
[0053] A spun Viscose challis (ISO-105/F02, Testfabrics' style 266,
weighing 4.07 osy) treated as above, did not ignite even after a 4
second flame impingement.
EXAMPLE 5
[0054] 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.
[0055] The same results were obtained when bees wax was substituted
for the candelilla wax.
[0056] The same results were obtained when a 50/50 emulsified blend
of Jojoba and Carnauba was employed.
[0057] The desized and bleach print cloth (Testfabrics' style 400)
cited above was treated with 1.0% blend (50/50 w/w) mixture of
Oleic and Stearic acid at 75% 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
[0058] 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 CFR 25.853(b), which is
incorporated herewith by reference. The test is performed as
follows:
[0059] A minimum of three 1''.times.6''.times.6'' (2.54
cm.times.15.24 cm.times.15.24 cm) specimens (derived from a batting
of the bi-regional Whole Cotton fibers of Example 5 are prepared.
The specimens are conditioned by maintaining them in a conditioning
room maintained at a temperature of 70.degree. C..+-.3.degree. and
5% relative humidity for 24 hours preceding the test.
[0060] 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. 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.
[0061] Pursuant to the test, the material is self-extinguishing.
The average burn length does not exceed 8 in. (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.
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