U.S. patent application number 16/924296 was filed with the patent office on 2020-10-29 for bleaching and shive reduction process for non-wood fibers.
The applicant listed for this patent is CRAILAR TECHNOLOGIES, INC., GPCP IP Holdings LLC. Invention is credited to Raymond Jeffrey Harwood, Jeffrey A. Lee, Edward J. Smith, Alan E. Wright.
Application Number | 20200340172 16/924296 |
Document ID | / |
Family ID | 1000004987395 |
Filed Date | 2020-10-29 |
![](/patent/app/20200340172/US20200340172A1-20201029-D00000.png)
![](/patent/app/20200340172/US20200340172A1-20201029-D00001.png)
![](/patent/app/20200340172/US20200340172A1-20201029-D00002.png)
![](/patent/app/20200340172/US20200340172A1-20201029-D00003.png)
![](/patent/app/20200340172/US20200340172A1-20201029-D00004.png)
![](/patent/app/20200340172/US20200340172A1-20201029-D00005.png)
![](/patent/app/20200340172/US20200340172A1-20201029-D00006.png)
![](/patent/app/20200340172/US20200340172A1-20201029-D00007.png)
![](/patent/app/20200340172/US20200340172A1-20201029-D00008.png)
![](/patent/app/20200340172/US20200340172A1-20201029-D00009.png)
![](/patent/app/20200340172/US20200340172A1-20201029-D00010.png)
View All Diagrams
United States Patent
Application |
20200340172 |
Kind Code |
A1 |
Lee; Jeffrey A. ; et
al. |
October 29, 2020 |
BLEACHING AND SHIVE REDUCTION PROCESS FOR NON-WOOD FIBERS
Abstract
The present invention is directed to a method for scouring and
increasing the brightness of non-wood fibers. The method comprises
forming a mixture of non-wood fibers, exposing the mixture to a
scouring liquor and a scouring agent comprising oxygen gas to form
a scouring mixture, and scouring the scouring mixture by radially
circulating the scouring liquor throughout the scouring mixture to
provide scoured fibers.
Inventors: |
Lee; Jeffrey A.; (Neenah,
WI) ; Harwood; Raymond Jeffrey; (Leicestershire,
GB) ; Smith; Edward J.; (Leicestershire, GB) ;
Wright; Alan E.; (Marietta, GA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GPCP IP Holdings LLC
CRAILAR TECHNOLOGIES, INC. |
Atlanta
Victoria |
GA |
US
CA |
|
|
Family ID: |
1000004987395 |
Appl. No.: |
16/924296 |
Filed: |
July 9, 2020 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
14716247 |
May 19, 2015 |
10711399 |
|
|
16924296 |
|
|
|
|
62000846 |
May 20, 2014 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D01C 1/02 20130101; D06L
4/621 20170101; D06L 4/671 20170101 |
International
Class: |
D06L 4/671 20060101
D06L004/671; D01C 1/02 20060101 D01C001/02; D06L 4/621 20060101
D06L004/621 |
Claims
1. An article, comprising: scoured and brightened bast fibers
comprising a mean length of at least 7 millimeters (mm); and a
brightness of at least 70 as measured by Technical Association of
the Pulp and Paper Industry (TAPPI) 525 standard test method;
wherein the article is a yarn, a thread, a rope, a cord, or a
sliver.
2. The article of claim 1, wherein the scoured and brightened bast
fibers are flax fibers, hemp fibers, jute fibers, ramie fibers,
nettle fibers, Spanish broom fibers, kenaf plant fibers, or any
combination thereof.
3. The article of claim 1, further comprising a lubricant, a
finish, an antistatic agent, or a combination thereof.
4. The article of claim 1, further comprising synthetic fibers,
polymeric fibers, thermoplastic fibers, staple fibers, regenerated
cellulose fibers, cotton fibers, wood pulp fibers, or a combination
thereof.
5. A fabric, comprising: scoured and brightened bast fibers
comprising a mean length of at least 7 millimeters (mm); and a
brightness of at least 70 as measured by Technical Association of
the Pulp and Paper Industry (TAPPI) 525 standard test method;
wherein the fabric is a woven fabric or a knit fabric.
6. The fabric of claim 5, wherein the fabric comprises a yarn, a
thread, a rope, or a combination thereof.
7. The fabric of claim 5, wherein the scoured bast fibers are flax
fibers, hemp fibers, jute fibers, ramie fibers, nettle fibers,
Spanish broom fibers, kenaf plant fibers, or any combination
thereof.
8. The fabric of claim 5, further comprising synthetic fibers,
polymeric fibers, thermoplastic fibers, staple fibers, regenerated
cellulose fibers, natural fibers, or a combination thereof.
9. The fabric of claim 8, wherein the natural fibers are cotton
fibers.
10. The fabric of claim 8, wherein the polymeric fibers are
polyester fibers.
11. The fabric of claim 5, wherein the fabric is or is used in a
wet wiper, a dry wiper, an impregnated wiper, a sorbent, a clean
room wiper, a medical supply product, a personal protective fabric,
an automotive protective covering, a personal care article, a fluid
filtration product, a home furnishing product, a thermal insulation
product, an acoustic insulation product, an agricultural
application product, a landscaping application product, or a
geotextile application product.
12. The fabric of claim 5, wherein the fabric is or is used in a
baby wipe, a cosmetic wipe, a perinea wipe, a washcloth, a kitchen
wipe, a bath wipe, a hard surface wipe, a glass wipe, a mirror
wipe, a leather wipe, an electronics wipe, a lens wipe, a polishing
wipe, a medical cleaning wipe, a disinfecting wipe, an industrial
wipe, a food service wipe, a surgical drape, a surgical gown, a
wound care product, a protective coverall, a sleeve protector, a
diaper, a feminine care article, a nursing pad, an air filter, a
water filter, an oil filter, a furniture backing, or a surgical
mask.
13. An article, comprising: scoured and brightened bast fibers
comprising a mean length at least 7 millimeters (mm); and a
brightness of at least 70 as measured by Technical Association of
the Pulp and Paper Industry (TAPPI) 525 standard test method;
wherein the article is an article of clothing or a home
furnishing.
14. The article of claim 13, wherein the article of clothing is a
shirt, a blouse, a sweater, a sweatshirt, a top, pants, trousers, a
tank top, a leotard, a sport specific clothing, a sock, an
undergarment, a hat, a belt, a jacket, a coat, a vest, a glove, a
dress, a skirt, a scarf, a bib, an apron, footware, or a
combination thereof.
15. The article of claim 13, wherein the home furnishing is a
drapery, a sheet, a towel, a chair covering, a sofa covering, a
furniture upholstery, a seat cover, a table cloth, a cushion
covering, a pillow covering, or a combination thereof.
16. The article of claim 13, wherein the scoured bast fibers are
flax fibers, hemp fibers, jute fibers, ramie fibers, nettle fibers,
Spanish broom fibers, kenaf plant fibers, or any combination
thereof.
17. The article of claim 13, further comprising synthetic fibers,
polymeric fibers, thermoplastic fibers, staple fibers, regenerated
cellulose fibers, natural fibers, or a combination thereof.
18. The article of claim 17, wherein the natural fibers are cotton
fibers.
19. The article of claim 17, wherein the polymeric fibers are
polyester fibers.
20. A composite material comprising: scoured and brightened bast
fibers comprising a mean length of at least 7 millimeters (mm); a
brightness of at least 70 as measured by Technical Association of
the Pulp and Paper Industry (TAPPI) 525 standard test method; and a
matrix material.
21. The composite material of claim 20, wherein the matrix material
comprises a thermoplastic material or a thermoset material.
22. The composite material of claim 21, wherein the thermoplastic
material is polypropylene, polyethylene, polystyrene, polyvinyl
chloride, poly(hydridocarbyne), polyhydroxybutyrate, or a
combination thereof.
23. The composite material of claim 21, wherein the thermoset
material is an epoxy resin, a phenolic resin, a polyurethane, a
polyester, a vinyl resin, an acrylate resin, or a combination
thereof.
24. The composite material of claim 20, wherein the scoured bast
fibers are randomly or substantially uniformly distributed
throughout the matrix material.
25. The composite material of claim 20, wherein the scoured bast
fibers are in a form of a nonwoven fabric or a woven fabric.
26. The composite material of claim 20, wherein the composite
material is an automobile part, an aviation part, a marine part, a
home furnishing, a building panel, or a combination thereof.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 14/716,247, filed May 19, 2015, which claims
benefit of U.S. Provisional Patent Application Ser. No. 62/000,846,
filed May 20, 2014, both of which are incorporated herein in their
entirety by reference.
TECHNICAL FIELD
[0002] The instant invention generally is related to methods for
fiber production. More specifically, the instant invention is
related to methods for non-wood fiber scouring methods.
BACKGROUND OF THE INVENTION
[0003] Plant fibers fall into three groups: seed fibers (e.g.,
cotton and kapok), stem fibers (bast fibers, e.g., flax and hemp),
and leaf fibers (e.g., sisal and kenaf). Bast fibers occur as
bundles of fibers, which extend through the length of the plant
stems, located between the outer epidermal "skin" layers and the
inner woody core (cortex) of the plant. Therefore, bast fiber straw
includes three primary concentric layers: a bark-like skin covering
layer, a bast fiber layer, and an inner, woody core. The woody core
has various names, which depends on the particular plant type. For
example, the flax woody core is referred to as "shive." Thus,
"shive" refers to all woody-core materials contained in bast fiber
plants.
[0004] The bundles of fibers are embedded in a matrix of pectins,
hemi-celluloses, and some lignin. The lignin must be degraded, for
example by "retting" (partial rotting) of the straw, for example by
enzymes produced by fungi (e.g., during dew-retting), or bacteria
(e.g., during water-retting). Decortication involves mechanically
bending and breaking the straw to separate the fiber bundles from
the shive and skin layers, and then removing the non-fiber
materials using a series of conventional mechanical cleaning
stages.
[0005] A substantial proportion of the pectin-containing material
that surrounds the individual bast fibers is pectin, with the
remaining portion being primarily various water-soluble
constituents. Pectin is a carbohydrate polymer, which includes
partially-methylated poly-galacturonic acid with free carboxylic
acid groups present as calcium salts. Pectin is generally insoluble
in water or acid, but may be broken down, or hydrolyzed, in an
alkaline solution, such as an aqueous solution of sodium
hydroxide.
[0006] Removal of the pectin-containing material, or gum, is
necessary in many instances to utilize the fiber for its intended
purposes. Various methods for pectin removal include degumming, or
removing, the pectin-containing substances from the individual bast
fiber. For example, U.S. Pat. No. 2,407,227 discloses a retting
process for the treatment of fibrous vegetable or plant material,
such as flax, ramie, and hemp. The retting process employs
micro-organisms and moisture to dissolve or rot away much of the
cellular tissues and pectins surrounding fiber bundles,
facilitating separation of the fiber bundles from the shive and
other non-fiber portions of the stem. Thus, the waxy, resinous, or
gummy binding substances present in the plant structure are removed
or broken down by means of fermentation.
[0007] Following retting, the stalks are broken, and then a series
of chemical and mechanical steps are performed to produce
individual or small bundles of cellulose fiber. Scouring is a
cleaning procedure that removes impurities from fibers (e.g.,
natural impurities, such as wax and pectin, and contaminants, such
as microbes). Typically, scouring is performed by exposing fibers
to chemicals in a sealed, temperature and pressure-controlled
chamber, such as a fiber processing kier.
[0008] However, a common problem still occurring in non-wood fiber
processes is the occurrence shives, which are undesirable particles
in finished paper products. Shives includes pieces of stems,
"straw," dermal tissue, epidermal tissue, and the like. Shives are
substantially resistant to defiberizing processes, rendering their
presence problematic. Even following oxidative bleaching, shives
continue to have deleterious effects on the appearance, surface
smoothness, ink receptivity, and brightness of a finished paper
product. Mechanical removal of shive to the level required for a
high value product involves the application of significant
mechanical energy, which results in fiber breakage and generation
of fines, or small cellulose particles. The fines are a yield loss,
increasing the production cost. Further, the broken fibers reduce
the overall fiber strength so they either cannot be used in some
manufacturing processes and/or result in weak textile or paper
products.
[0009] Thus, conventional methods of non-wood fiber processing are
not sufficiently robust to remove, decolorize, and break up the
residual shive present in the fibers. Thus, processed and finished
fibers can still include particles of shive, which are both
aesthetically unattractive and reduce the commercial value of the
fiber product. Furthermore, conventional bleaching processes are
not sufficiently robust to increase paper brightness to sufficient
levels required for commercial products.
[0010] Accordingly, there exists an on-going need for a method to
both adequately bleach and sufficiently reduce shive presence in
non-wood fibers. Thus, the present invention is directed to meeting
this and other needs and solving the problems described above.
SUMMARY OF THE INVENTION
[0011] It is to be understood that the phraseology and terminology
employed herein are for the purpose of description and should not
be regarded as limiting. As such, those skilled in the art will
appreciate that the conception, upon which this disclosure is
based, may readily be utilized as a basis for the designing of
other structures, methods, and systems for carrying out the present
invention. It is important, therefore, that the claims be regarded
as including such equivalent constructions insofar as they do not
depart from the spirit and scope of the present invention.
[0012] In one aspect of the present invention, a method for
scouring and increasing the brightness of non-wood fibers comprises
forming a mixture of non-wood fibers, exposing the mixture to a
scouring liquor and a scouring agent comprising oxygen gas to form
a scouring mixture, and scouring the scouring mixture by, for
example, radially circulating the scouring liquor throughout the
scouring mixture in a chamber to provide scoured fibers.
[0013] In another aspect, a method for increasing the brightness of
non-wood fibers comprises forming a mixture of non-wood fibers and
scouring the mixture in the presence of a scouring agent comprising
oxygen gas to provide scoured and brightened fibers. The resulting
scoured and brightened fiber has a brightness in a range between
about 30 and about 60 as measured by Technical Association of the
Pulp and Paper Industry (TAPPI) 525 standard test method.
[0014] Yet in another aspect, a method of reducing the amount of
residual shive in non-wood fibers comprises forming a mixture of
non-wood fibers and scouring the mixture in the presence of a
scouring agent comprising oxygen gas to provide scoured and
low-shive fibers. The low-shive fibers have less visible shive
content than the fibers of the mixture before exposure.
[0015] Other advantages and capabilities of the invention will
become apparent from the following description taken in conjunction
with the examples showing aspects of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The invention will be better understood and the above object
as well as other objects other than those set forth above will
become apparent when consideration is given to the following
detailed description thereof. Such description makes reference to
the annexed drawing wherein:
[0017] FIG. 1 is an illustration of a method for introducing oxygen
gas into a kier using a circulation pump to mix and dissolve the
oxygen.
[0018] FIG. 2 is an illustration of a method for introducing oxygen
into a mixer after the circulation pump.
[0019] FIG. 3 is an illustration of a method for introducing oxygen
directly into the non-wood fibers.
[0020] FIG. 4 is an illustration of a method for exposing the
non-wood fibers to oxygen using an internal and external liquor
circulation system.
[0021] FIG. 5 is an illustration of a method for cooling the liquor
in the system of FIG. 4.
[0022] FIG. 6 is an illustration of a method for using oxygen to
displace the residual liquor from the fibers in the system of FIG.
4.
[0023] FIG. 7 is an illustration of another method for using oxygen
to displace the residual liquor from the fibers in the system of
FIG. 4.
[0024] FIG. 8 is an illustration of a control system for oxygen
brightening of non-wood fibers.
[0025] FIG. 9 is a graph of liquor solids as a function of
time.
[0026] FIG. 10 is a graph of the liquor caustic (NaOH)
concentration as a function of time.
[0027] FIG. 11 is a graph of the liquor caustic (NaOH)
concentration at different scouring temperatures as a function of
time.
[0028] FIG. 12 is a graph of the liquor solids content at different
scouring temperatures as a function of time.
DETAILED DESCRIPTION OF THE INVENTION
[0029] For a fuller understanding of the nature and desired objects
of this invention, reference should be made to the above and
following detailed description taken in connection with the
accompanying figures. When reference is made to the figures, like
reference numerals designate corresponding parts throughout the
several figures.
[0030] In one aspect of the present invention, a method for
scouring and increasing the brightness of non-wood fibers comprises
forming a mixture of non-wood fibers, exposing the mixture to a
scouring liquor and a scouring agent comprising oxygen gas to form
a scouring mixture, and scouring the scouring mixture by radially
circulating the scouring liquor throughout the scouring mixture to
provide scoured fibers.
[0031] In another aspect, a method for increasing the brightness of
non-wood fibers comprises forming a mixture of non-wood fibers and
scouring the mixture in the presence of a scouring agent comprising
oxygen gas to provide scoured and brightened fibers. The brightened
fibers have a brightness in a range between about 30 and about 60
as measured by TAPPI 525 standard test method. The higher
brightness achieved in the scouring step can also eliminate the
need for a bleaching step, as the brightness may be high enough for
many applications. Optionally, subsequent bleaching steps,
including bleaching with oxidizing agents and/or bleaching with a
reducing agent, can be performed to further increase brightness of
the fibers. The additional bleaching steps also can be performed in
the presence of oxygen gas.
[0032] Yet in another aspect, a method of reducing the amount of
residual shive in non-wood fibers comprises forming a mixture of
non-wood fibers and scouring the mixture in the presence of a
scouring agent to provide scoured and low-shive fibers. The
scouring agent is oxygen gas, an organic acid, or a combination of
the oxygen gas and the organic acid, and the scoured and low-shive
fibers have less visible shive content than the fibers of the
mixture before exposure.
[0033] The following definitions and abbreviations are to be used
for the interpretation of the claims and the specification. As used
herein, the terms "comprises," "comprising," "includes,"
"including," "has," "having," "contains" or "containing," or any
other variation thereof, are intended to cover a non-exclusive
inclusion. For example, a composition, a mixture, process, method,
article, or apparatus that comprises a list of elements is not
necessarily limited to only those elements but can include other
elements not expressly listed or inherent to such composition,
mixture, process, method, article, or apparatus.
[0034] As used herein, the articles "a" and "an" preceding an
element or component are intended to be nonrestrictive regarding
the number of instances (i.e. occurrences) of the element or
component. Therefore, "a" or "an" should be read to include one or
at least one, and the singular word form of the element or
component also includes the plural unless the number is obviously
meant to be singular.
[0035] As used herein, the terms "invention" or "present invention"
are non-limiting terms and not intended to refer to any single
aspect of the particular invention but encompass all possible
aspects as described in the specification and the claims.
[0036] As used herein, the term "about" modifying the quantity of
an ingredient, component, or reactant of the invention employed
refers to variation in the numerical quantity that can occur, for
example, through typical measuring and liquid handling procedures
used for making concentrates or solutions. Furthermore, variation
can occur from inadvertent error in measuring procedures,
differences in the manufacture, source, or purity of the
ingredients employed to make the compositions or carry out the
methods, and the like. In one aspect, the term "about" means within
10% of the reported numerical value. In another aspect, "about"
means within 5% of the reported numerical value.
[0037] As used herein, the terms "percent by weight," "% by
weight," and "wt. %" mean the weight of a pure substance divided by
the total dry weight of a compound or composition, multiplied by
100. Typically, "weight" is measured in grams (g). For example, a
composition with a total weight of 100 grams, which includes 25
grams of substance A, will include substance A in 25% by
weight.
[0038] As used herein, the term "non-wood fibers" means fibers
produced by and extracted from a plant or animal, with the
exception that such fibers do not include wood fibers, i.e.,
derived from a tree, and man-made fibers formed from cellulose,
e.g. viscose. Non-limiting examples of suitable non-wood fibers are
plant-based, non-wood fibers, such as bast fibers. Bast fibers
include, but are not limited to, flax fibers, hemp fibers, jute
fibers, ramie fibers, nettle fibers, Spanish broom fibers, kenaf
plant fibers, or any combination thereof. Non-wood fibers include
seed hair fibers, for example, cotton fibers. Non-wood fibers can
also include animal fibers, for example, wool, goat hair, human
hair, and the like.
[0039] As used herein, the term "nonwoven" means a web or fabric
having a structure of individual fibers or threads which are
randomly interlaid, but not in an identifiable manner as in the
case of a knitted or woven fabric. Examples of suitable nonwoven
fabrics or webs include, but are not limited to, meltblown webs,
spunbound webs, bonded carded webs, airlaid webs, coform webs,
hydraulically entangled webs, and so forth.
[0040] As used herein, the term "kier" means a circular boiler or
vat used in processing, bleaching and/or scouring non-wood fibers.
As used herein, the term "scour," "scouring," or "scoured" refers
to a cleaning procedure that removes impurities from fibers (e.g.,
natural impurities, such as wax and pectin, and contaminants, such
as microbes). Typically, scouring is performed by exposing fibers
to chemicals in a sealed, temperature and pressure-controlled
chamber. Subsequently, the fiber can be bleached to decolorize
impurities and increase the fiber brightness.
[0041] As used herein, the term "scouring liquor" means an aqueous
composition used in the scouring process. The scouring liquor can
be of any composition known to those in the art for scouring
non-wood fibers and can have a neutral or alkali pH. The scouring
liquor can include an alkali, for example sodium hydroxide,
magnesium hydroxide, or a combination thereof. Other non-limiting
examples of suitable components include sodium carbonate, magnesium
sulfate, surfactants, or any combination thereof.
[0042] As used herein, the term "scouring agent(s)" means oxygen
gas, an organic acid or salt thereof, or any combination thereof.
The oxygen gas and organic acid can be utilized in the scouring
agent in a sequence. For example, the non-wood fibers can be
exposed to the oxygen gas and then the organic acid in a sequence.
Alternatively, the non-wood fibers can be exposed to organic acid
in a pre-treatment step before scouring with oxygen gas. The
scouring agent can further include other gases, for example
nitrogen or carbon dioxide. The oxygen gas can be present as a
mixture with other gases. In one example, the oxygen gas is present
in the scouring agent about or in any range between about 75, 80,
85, 90, 95, and 100%.
[0043] As used herein, the term "brightness" refers to the
whiteness of a composition of fibers. Brightness can be determined
by TAPPI 525 test method. Briefly, the fiber is dried using warm
air and then carded. The fiber brightness is determined using a
Datacolor SF600 Plus-CT reflectance spectrophotometer. Four
measurements of each sample are averaged. The sample is illuminated
with a CIE D65 source through a 20 mm diameter aperture. The
observer conditions are 10.degree. visual field, with the specular
component being included, and the UV filter in an off position. The
TAPPI 525 brightness value (also the CIE whiteness index and CIE
L*a*b* values) is calculated using ColorTools QC software.
[0044] Another method of measuring brightness includes the "MacBeth
UV-C" test method, utilizing a Macbeth 3100 spectrophotometer,
commercially available from X-Rite, Inc., Grand Rapids, Mich. UV-C
is the illuminant (lamp) used for brightness testing. As used
herein, the term "gain" means the increase in fiber brightness
following a bleaching process. Brightness and gain measurements of
the fibers, before and after exposure to the brightening agent, are
conducted on thick pads of the fiber. The fiber pads are prepared
by diluting the fibers to a consistency in a range between about 2%
and about 10% with water, mixing to separate the fibers, and then
de-watering the fibers, for example on a Buchner funnel with a
filter paper, to form the fiber pad. The fiber pad can be further
dewatered by pressing between blotters in a laboratory press and
then dried on a speed dryer to form a dry cake. The fiber pads can
then be air-dried for several days prior to brightness testing.
Brightness measurements also can be done on the fiber by: 1) drying
the fiber with hot air to less than 2-4% moisture, 2) carding the
fiber to straighten out and align the fibers into a mat, lap or
sliver, and 3) measuring the brightness of the lap, mat or sliver.
Brightness and gain testing of the fibers according to the MacBeth
UV-C brightness standard is conducted before and after exposure to
the brightening agent, with the brightened fibers having a
brightness greater than the fibers before exposure. The MacBeth
test measures both TAPPI brightness and LAB whiteness. L* is the
whiteness/lightness, and a* and b* are the color (red-green and
blue-yellow). A* and b* values close to 0 indicate very low
color/no color. The UV-C test measures the illuminate, including
the both the ultraviolet and color components of the light.
[0045] As used herein, the term "gain" means the increase in fiber
brightness following a bleaching process.
[0046] As used herein, the term "consistency" means to the percent
(%) solid in a composition comprising a solid in a liquid carrier.
For example, the consistency of a fiber composition weighing 100
grams and comprising 50 grams of fibers has a consistency of
50%.
[0047] As used herein, the terms "cellulose fibers," "cellulosic
fibers," and the like refer to any fibers comprising cellulose.
Cellulose fibers include secondary or recycled fibers, regenerated
fibers, or any combination thereof.
[0048] Conventional non-wood fiber production involves mechanical
removal of non-fiber shive material, followed by chemical removal
of pectin and a mild oxidative bleaching step. Plants, including
flax, require an initial "retting" step before mechanical removal
of non-fiber material. The retting process employs micro-organisms
and moisture to dissolve or rot away much of the cellular tissues
and pectins surrounding fiber bundles, thus facilitating separation
of the fiber from the stem. Thus, waxy, resinous, or gummy binding
substances present in the plant structure are removed or broken
down by means of fermentation. Pectin removal can be accomplished
using an alkaline agent, such as sodium hydroxide, at elevated
temperatures. Enzymes and other chemicals, such as detergents and
wetting agents, also can be added to enhance pectin detachment from
the fibers. U.S. Pat. Nos. 8,603,802 and 8,591,701 and Canadian
Patent No. CA 2,745,606 disclose methods for pectin removal using
enzymes. Following the pectin extraction step, the fibers are
washed and treated with a mixture of hydrogen peroxide and sodium
hydroxide to increase the brightness and whiteness of the finished
fiber.
[0049] However, there are drawbacks to these conventional methods.
First, available pectin extraction and bleaching steps are not
robust enough to decolorize and/or break up residual shive in the
fiber. Second, the bleaching process also is not robust enough to
increase the brightness to levels required for high quality
commercial products. The result is finished fibers containing dark
shive particles, which is aesthetically unappealing and reduces the
commercial value of the fiber product. The shive also interferes
with the manufacturing processes which utilize the fiber. For
example, particles of shive can plug the filters on a
hydroentanglement system. The shive also has very low bonding
ability. Thus, any shive entrained in the finished product be
unappealing to the end user. Further, residual shive could also be
a potential source of contamination when used, for example, in food
service wipes.
[0050] In particular, the only way current method to remove the
shive is extensive mechanical cleaning and carding, which is
expensive, causes fiber damage, and reduces yield. In contrast, the
inventive process disclosed herein enhances one of the existing
process steps, reducing or even eliminating the need for the
additional mechanical removal steps.
[0051] One commercially available solution to the shive problem is
to either increase the intensity of the mechanical shive removal
process or to add multiple mechanical removal stages so that the
residual shive content is low enough to be imperceptible in the
finished product. However, this solution has drawbacks. First,
additional mechanical processing increases the operating and
capital costs of production. Second, the additional mechanical
processing damages the fragile fibers, resulting in a product with
inferior tensile strength properties. Finally, additional
mechanical processing reduces the yield of the finished fiber
because of the generation of fines, or small cellulose particles,
and long fiber losses due to the inherent inefficiency of
mechanical processing.
[0052] As disclosed herein, exposing fibers to oxygen gas during or
at the end of the scouring process increases the brightness of the
fibers and reduces the residual shive to levels that dramatically
reduce the impact of shive on the appearance of the finished fiber.
Furthermore, and without being bound by theory, it is believed that
the scouring process disclosed herein reduces the integrity of the
shives so that they are more easily broken up and removed in
mechanical treatment. Reduced shive content after exposure to the
scouring agent, which includes oxygen gas, can be assessed by
visual examination of the fibers. To further increase brightness,
the fibers can be pre-treated with an organic acid, or exposed to
the organic acid after scouring in the presence of oxygen gas.
[0053] Furthermore, the disclosed process provides a significantly
higher brightness compared to conventional processes, which results
in production of fibers with higher commercial value. Thus, the
process can be used to produce a commercially useful fiber from low
quality raw materials that cannot be suitably processed with
conventional processes. Moreover, the process is suitable for a
variety of lower value plant fiber raw materials that cannot be
transformed into a commercially useful fiber without using other
processes. The effectiveness of oxygen gas addition during fiber
scouring allows for a significant reduction in the amount of alkali
required to effectively scour fibers, while still providing a
competitive brightness result. Further, the effectiveness of oxygen
gas addition during fiber scouring allows for a significant
reduction in the temperature required to effectively scour fibers,
which increases Fiber brightness and reduces fiber damage. Thus,
the fibers maintain high fiber strength throughout the process.
[0054] One type of non-wood fibers is bast fibers. Bast fibers are
found in the stalks of the flax, hemp, jute, ramie, nettle, Spanish
broom, and kenaf plants, to name a few. Typically, native state
bast fibers are 1 to 4 meters in length. These long native state
fibers are comprised of bundles of straight individual fibers that
have lengths between 20-100 millimeters (mm). The bundled
individual fibers are glued together by pectins (a class of plant
resins).
[0055] Bast fibers bundles can be used for both woven textiles and
cordage. An example of a woven textile produced with flax bast
fiber bundles is linen. More recently, as provided in U.S. Pat. No.
7,481,843, partially separated bast fiber is produced to form yarns
and threads for woven textiles. However, yarns and threads are not
suited for nonwoven fabrics.
[0056] Any non-wood fibers can be used in the present invention. In
one example, suitable fibers include cotton fibers, bast fibers, or
any combination thereof. Bast fibers can be derived from a variety
of raw materials. Non-limiting examples of suitable bast fibers
include, but are not limited to, flax fibers, hemp fibers, jute
fibers, ramie fibers, nettle fibers, Spanish broom fibers, kenaf
plant fibers, or any combination thereof. Secondary or recycled
fibers from waste paper can be used.
[0057] Initially, pectin can be substantially removed from
pectin-containing non-wood fibers to form substantially
individualized fibers. Thus, the fibers are rendered substantially
straight and are substantially pectin-free. The fibers can be
individualized, by pectin removal, using mechanical or chemical
means.
[0058] Enzymatic treatment is a non-limiting example of a chemical
treatment that can be used to substantially remove pectin. PCT
International Publication No. WO 2007/140578, which is incorporated
herein in its entirety by reference, describes a pectin removal
technology which produces individualized hemp and flax fiber for
application in the woven textile industry. The process to remove
pectin described in WO 2007/140578 can be employed in the invention
described herein to produce substantially individualized non-wood
fibers.
[0059] Individualized non-wood fibers can have less than 10% by
weight of the pectin content of the naturally occurring fibers from
which the substantially pectin-free fibers are derived. In another
aspect, individualized non-wood fibers have less than 15% by weight
of the pectin content of the naturally occurring fibers from which
the substantially pectin-free fibers are derived. Still, in another
aspect, individualized non-wood fibers have less than 20% by weight
of the pectin content of the naturally occurring fibers from which
the substantially pectin-free fibers are derived. Still, in another
aspect, individualized non-wood fibers have less than 0.1% by
weight, less than 0.15% by weight, or less than 0.20% by weight, of
the pectin content of the naturally occurring fibers from which the
substantially pectin-free fibers are derived. In one aspect, the
individualized non-wood fibers have less than about 20%, 19%, 18%,
17%, 16%, 15%, 14%, 13%, 12%, 11% 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%,
2%, 1%, 0.5%, and 0.25% by weight of the pectin content of the
naturally occurring fibers from which the substantially pectin-free
fibers are derived.
[0060] The non-wood fibers can have a mean length in a range
between about 0.5 and 500 mm depending on the characteristics of
the particular fibers and the cut length of the plant stalks prior
to chemical processing. In one aspect, the individualized non-wood
fibers have a mean length of at least 7 mm, at least 8 mm, at least
9 mm, and at least 10 mm. In another aspect, the individualized
non-wood fibers have a mean length greater than 12 mm. Still yet,
in another aspect, the non-wood, plant based fibers have a mean
length about or in a range between about 1, 2, 3, 4, 5, 6, 7, 8, 9,
10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20, 50, 100, 125, 150,
175, 200, 225, 250, 275, 300, 325, 350, 325, 350, 375, 400, 425,
450, 475, and 500 mm.
[0061] In addition to non-wood fibers, the fiber mixture can
include fibers derived from one or more source, including, but not
limited to, cellulosic fibers, including staple fibers and
regenerated cellulose, and thermoplastic fibers. Optionally, the
cellulosic fibers are secondary, recycled fibers. Non-limiting
examples of cellulosic fibers include, but are not limited to,
hardwood fibers, such as hardwood kraft fibers or hardwood sulfite
fibers; softwood fibers, such as softwood kraft fibers or softwood
sulfite fibers; or any combination thereof. Non-limiting examples
of regenerated cellulose include RAYON.RTM., lyocell, (e.g.,
TENCEL.RTM.), viscose, or any combination thereof. TENCEL.RTM. and
RAYON.RTM. are commercially available from Lenzing
Aktiengesellschaft, Lenzing, Austria.
[0062] In one aspect, the mixture of non-wood fibers includes
synthetic, polymeric, thermoplastic fibers, or any combination
thereof. Thermoplastic fibers include the conventional polymeric
fibers utilized in the nonwoven industry. Such fibers are formed
from polymers which include, but are not limited to, a polyester
such as polyethylene terephthalate; a nylon; a polyamide; a
polypropylene; a polyolefin such as polypropylene or polyethylene;
a blend of two or more of a polyester, a nylon, a polyamide, or a
polyolefin; a bi-component composite of any two of a polyester, a
nylon, a polyamide, or a polyolefin; and the like. An example of a
bi-component composite fiber includes, but is not limited to, a
fiber having a core of one polymer and a sheath comprising a
polymer different from the core polymer which completely,
substantially, or partially encloses the core.
[0063] Brightness measurements of the scoured fibers (e.g., scoured
bast fibers), before and after subjecting the fibers to the
inventive scouring method, can be conducted on thick pads of the
fiber. The fiber pads can be prepared by diluting the fibers to a
consistency in a range between about 1% and about 10% with water,
mixing to separate the fibers, and then de-watering the fibers, for
example on a Buchner funnel with a filter paper, to form the fiber
pad. The fiber pad can be further dewatered by pressing between
blotters in a laboratory press and then dried on a speed dryer to
form a dry cake. The fiber pads can then be air-dried for several
days prior to brightness testing.
[0064] Brightness testing of the oxygen scoured fibers (e.g.,
scoured bast fibers) according to the TAPPI 525 test method is
conducted before and after scouring, and following optional
subsequent bleaching steps. After being subjected to the presently
disclosed oxygen scouring method, the oxygen scoured and brightened
fibers have a brightness greater than the fibers before scouring.
After oxygen scouring and brightening, the fibers can have a
brightness in a range between about 25 and about 60 as measured by
the TAPPI 525 standard. In one aspect, the oxygen scoured fibers
and brightened fibers have a brightness in a range between about 35
and about 60. In another aspect, the oxygen scoured and brightened
fibers have a brightness in a range between about 45 and about 60.
Yet, in another aspect, after oxygen scouring, the oxygen scoured
and brightened fibers have a brightness in a range between about 40
and about 50. In some aspects, after oxygen scouring and subsequent
bleaching processes (e.g., one, two, three or more), the scoured
and brightened fibers have a further improved brightness of at
least 65, at least 66, at least 67, at least 68, at least 69, at
least 70, at least 71, at least 72, at least 73, at least 74, at
least 75, at least 76, at least 77, at least 78, at least 79, or at
least 80. Still other aspects, the oxygen scoured and optionally
bleached fibers have a brightness about or in any range between
about 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39,
40, 41, 42, 43, 44, 45, 46, 47, 48, 29, 50, 51, 52, 53, 54, 55, 56,
57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 67, 69, 70, 71, 72, 73,
74, 75, 76, 77, 78, 79, and 80 as measured by the TAPPI 525
standard.
[0065] The brightness gain or increase in fiber brightness
following scouring is in a range between about 10 and about 50 as
measured by TAPPI 525 standard. In one aspect, the brightness gain
is in a range between about 20 and about 40 as measured by TAPPI
525 standard. In another aspect, the brightness gain is in a range
between about 15 and about 30 as measured by TAPPI 525 standard.
Yet, in another aspect, the brightness gain is about or in any
range between about 10, 15, 20, 25, 30, 35, 40, 45, and 50 as
measured by TAPPI 525 standard.
[0066] The scoured and brightened fibers, which are optionally
bleached, of the present invention can be used for any nonwoven
fabric products or textiles, including air-laid, carded,
spunbonded, and hydroentangled substrates. In one aspect, a
nonwoven fabric comprises non-wood fibers having a brightness in a
range between about 30 and about 60 as measured by TAPPI 525
standard test method. In another aspect, the nonwoven fabric
includes non-wood fibers having a brightness of at least 70 as
measured by TAPPI 525 standard test method.
[0067] Non-wood fiber brightening can be accomplished by 1)
retting, mechanical separation and cleaning of bast fibers,
scouring as disclosed herein, and one or two stage
brightening/bleaching; or 2) retting, mechanical separation and
cleaning of bast fibers, scouring as disclosed herein, conventional
peroxide or other bleaching/pre-bleaching, and one or two stage
bleaching; or 3) retting, mechanical separation and cleaning of
bast fibers, scouring as disclosed herein, treatment with an
organic acid as disclosed herein, and one or two stage bleaching;
or 4) picking, ginning, scouring as disclosed herein, and one or
two stage bleaching.
[0068] Then, the non-wood fibers are combined to form a mixture.
Pectin removal by chemical methods can be performed before or after
forming the mixture. The mixture can be formed into a fibrous mat,
a fiber mat, a fiber pad, a thick fiber pad, a wet cake, or a
"donut" when used in a kier based system. Optionally, the mixture
can then be wetted before exposing the mixture to the brightening
agent. The mixture can be diluted to any desired consistency,
wetted, and/or combined with any desired additives, non-limiting
examples of which are mentioned below.
[0069] In the mixture before scouring, the fibers have a
consistency in a range between about 10% and about 50%. In one
aspect, the fibers in the mixture have a consistency in a range
between about 10% and about 30%. In another aspect, the fibers in
the mixture have a consistency in a range between about 15% and
about 35%. Yet in another aspect, the fibers in the mixture have a
consistency in a range between about 20% and about 40%. Still yet,
in another aspect, the fibers in the mixture have a consistency
about or in any range between about 10, 12, 15, 17, 20, 22, 25, 27,
30, 32, 35, 37, 40, 42, 45, 47 and 50%.
[0070] In a fiber processing kier system, the bleaching liquor, or
liquid, to fiber ratio can be in a range between about 10:1 to
about 20:1. In one aspect, the liquor/liquid to fiber ratio is in a
range between about 5:1 to 6:1. In another aspect, the
liquor/liquid to fiber ratio is in a range between about 12:1 to
about 18:1. However, lower liquor/liquid to fiber ratios, i.e., 5:1
compared to 10:1, may provide more desirable results.
[0071] To increase the brightness of the fibers, the fiber mixture
is scoured and exposed to a scouring agent, the scouring agent
being oxygen gas, an organic acid, or a combination of oxygen gas
and organic acid. The fiber mixture can be exposed to the scouring
agent by any suitable method.
[0072] Treating fibers with the scouring agent comprising oxygen
gas, before, during, or at the beginning and/or end of scouring
provides a substantial improvement in the brightness of the fibers,
as well as reduces dark color and the structural integrity of shive
contaminants. Although brightness is increased following the
inventive scouring process, additional subsequent bleaching stages
can further increase the brightness.
[0073] The fibers can be soaked in, rinsed with, or exposed to the
organic acid at any temperature, including room temperature or any
temperature above room temperature. The organic acid can be any
organic acid or salt thereof. Non-limiting examples of the organic
acid include acetic acid, citric acid (and citrate salts), formic
acid, lactic acid, oxalic acid, uric acid, or any combination
thereof. A wide variety of citrate salts can be employed, such as
alkali metal and alkaline-earth metal citrate salts. Non-limiting
examples of suitable citrate salts include calcium citrate,
tri-sodium citrate, or any combination thereof. Optionally, the
citrate salt is compounded with other materials.
[0074] The organic acid or salt thereof can be added to the fibers
in an amount in a range between about 0.1 and about 10 wt. % based
on the dry weight of the fibers. In one aspect, the organic acid or
salt thereof is added in an amount in a range between about 1 and
about 5 wt. % based on the dry weight of the fibers. In another
aspect, the organic acid or salt thereof is added in an amount in a
range between about 2 and about 8 wt. % based on the dry weight of
the fibers. Yet, in another aspect, the organic acid or salt
thereof is added in an amount about or in any range between about
0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5,
8, 8.5, 9, 9.5, and 10 wt. % based on the dry weight of the
fibers.
[0075] The scouring liquor can have an alkali or a neutral pH. In
one aspect, the scouring liquor has a neutral pH in a range between
about 6 and about 8. In another aspect, the scouring liquor has an
alkali pH in a range between about 7 and about 12. Yet, in another
aspect, the scouring liquor has a pH about or in any range between
about 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5,
12, 12.5, or 13.
[0076] The scouring liquor can include an alkali, for example
sodium hydroxide, magnesium hydroxide, or a combination thereof, to
provide an alkali pH. Other non-limiting examples of suitable
components include sodium carbonate, magnesium sulfate,
surfactants, or any combination thereof. However, even water alone
(neutral pH) can be used in the scouring liquor.
[0077] The use of magnesium compounds in the scouring liquor may
reduce the potential damage to the fibers that could occur during
oxygen exposure. In particular, the use of magnesium sulfate during
scouring with oxygen gas enhances the brightness gain and end
result, compared to oxygen gas alone. Thus, optionally, magnesium
hydroxide can be substituted for sodium hydroxide during
scouring.
[0078] Given the increased brightness with magnesium sulfate, other
magnesium compounds may provide the same result. Other magnesium
compounds include any magnesium salts or compounds including
magnesium. Non-limiting examples of suitable magnesium compounds
include magnesium hydroxide, magnesium oxide, magnesium sulfate,
magnesium glycinate, magnesium ascorbate, magnesium chloride,
magnesium orotate, magnesium citrate, magnesium fumarate, magnesium
malate, magnesium succinate, magnesium tartrate, magnesium
carbonate, magnesium hydroxide, or any combination thereof.
[0079] The magnesium compound can be added to the scouring liquor
or directly to the fibers. The optional magnesium compounds can be
added in an amount in a range between about 0.01 and about 5 wt. %
based on the total dry weight of the fibers. In one aspect, the
magnesium compound is added in an amount in a range between about
0.1 and about 3 wt. % based on the total dry weight of the fibers.
In another aspect, the magnesium compound is added in an amount in
a range between about 1 and about 4 wt. % based on the total weight
of the dry fibers. Yet in another aspect, the magnesium compound is
added in an amount about or in any range between about 0.1, 0.5, 1,
1.5, 2, 2.5, 3, 3.5, 4, 4.5, and 5 wt. % based on the total dry
weight of the fibers.
[0080] Referring to the figures, FIG. 1 illustrates an exemplary
method 100 of scouring and exposing the fibers to oxygen gas.
Although, the fibers can be exposed to the oxygen gas by any other
suitable method known in the art. The scour also can be run in a
continuous process.
[0081] Initially, dry, non-wood fibers are mixed with water, and,
optionally, subsequently centrifuged to remove most of the
remaining water. The fibers are disposed within the perforated
basket of a fiber processing kier 120. The basket is equipped with
a central perforated shaft to enable scouring liquor 140 to be
circulated radially through the fibers. The basket is also sealed
at the bottom and has a cover to seal at the top to ensure liquor
circulation through the fiber mass.
[0082] The scouring liquor 140 is prepared and introduced into the
fiber processing kier 120 and circulated through the fibers with
the circulation pump 140. Optionally, the scouring liquor is
pre-heated to 60-70.degree. C. to accelerate the heat-up cycle. In
one aspect, the scouring liquor is pre-heated to a temperature in a
range between about 50 and about 70.degree. C. In another aspect,
the scouring liquor is pre-heated to a temperature in a range
between about 55 and about 65.degree. C. Yet in another aspect, the
scouring liquor is pre-heated to a temperature in a range between
about 50 and about 60. Still yet, in another aspect, the scouring
liquor is pre-heated to a temperature about or in any range between
about 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, and 70.degree. C.
However, the upper temperature limiting is not intended to be
limited.
[0083] The scouring liquor 140 can be set to circulate from the
inside of the basket to the outside of the basket, or from the
outside to the inside. The system can be programmed to heat the
liquor to the desired treatment temperature and then to hold the
system at this temperature for the desired treatment time.
Periodically, the scouring liquor flow can be reversed to minimize
any channeling in the fiber. Thus, scouring can be performed in a
kier comprising an internal liquor circulation system or an
external liquor circulation system.
[0084] The oxygen gas 110 is injected into the circulation pump
130, which acts to mix and dissolve the oxygen gas 110 into the
scouring liquor 140. The oxygen gas 110 can be injected until the
desired system pressure is achieved, or until the oxygen gas is
dissolved in the solution, forming a dissolved oxygen scouring
liquor solution. Alternatively, a low, continuous flow of oxygen
can be maintained throughout the process. The oxygen gas can be
added at any point in the system, and the oxygen concentration is
controlled by adjusting the partial pressure. After scouring, and
optional bleaching or brightening steps, the scoured fibers can be
dried.
[0085] FIG. 2 illustrates another exemplary method 200 of exposing
the fiber mixture to oxygen gas 110. As shown, the oxygen gas 110
is introduced into a static or active mixing system 210 after the
circulation pump 130.
[0086] After pressurizing the fiber processing kier 120, or any
closed system, with oxygen gas, the oxygen can be vented one or
more times to flush air from the system. Venting ensures the
maximum possible dissolved oxygen concentration.
[0087] FIG. 3 illustrates another exemplary method 300 of exposing
the fiber mixture to the oxygen gas 110 at the end of the scouring
process. As shown, oxygen gas 110 is directly introduced into top
of the fiber processing Kier 120 after the fiber processing kier
120 is drained of scouring liquor 40. As such, the oxygen gas 110
displaces much of the residual liquor and permeates the fibers.
Thus, the oxygen gas 110 takes advantage of the residual heat and
scouring chemicals present in the fiber mat and reacts with the
chromophores and shive, reducing the content of shive. The
partially depleted oxygen can be purged, and a second and/or a
third oxygen charge can be added to enhance the liquor displacement
and improve the shive reduction and fiber brightness. The system
can be maintained under any desired temperature and/or pressure as
described above. As a result, the brightness of the fibers increase
and the residual shive content decreases, compared to the fibers
before scouring.
[0088] FIG. 4 illustrates an exemplary method 400 of exposing the
fiber mixture to oxygen gas 110 during scouring. Method 400 has an
additional internal circulation system 410 in addition to the
external liquor circulation systems of methods 100, 200, and 300
using the liquor circulation pump 130. Oxygen gas 110 is injected
into the liquor feed line 420 after the liquor circulation pump
130, which goes directly into the intake of the internal pump 412.
The entrained oxygen gas 110 enters the impeller 414, which mixes
and dissolves the oxygen gas 110 in the scouring liquor 140. The
scouring liquor 140, along with the dissolved oxygen 110 then
enters the center shaft 416 of the basket and then travels and
circulates through the fiber mass within the fiber processing Kier
120. The scouring liquor 140 moves from the center shaft 416
laterally through the fiber mass and then discharges back into the
fiber processing Kier 120, where it can move back to the liquor
circulation pump 130 for recirculation.
[0089] FIG. 5 is an illustration of a method 500 for cooling the
liquor in the method 400 shown in FIG. 4. In method 500, employing
a cooling system 510, the scouring liquor 140 from inside the fiber
processing Kier 120 is cooled below the flash temperature, for
example, less than about 100.degree. C., in a noncontact heat
exchanger 514 and then into a small liquor tank 516. A control
valve 512 controls the recirculation of the system and also holds
the pressure in the system. The cooled liquor 520 is then pumped
back into the liquor circulation pump 130 of the external
circulation system. The cooling system 510 allows for addition of
chemicals without depressurizing and emptying the fiber processing
kier 120.
[0090] The above system for cooling can be used for scouring at low
temperatures, for example below 110 or below 100.degree. C. In
fact, scouring at low temperatures provides desirable brightening
and maintains fiber strength, compared to scouring at higher
temperatures. For low temperature scouring with oxygen, the
temperature can be less than or in any range between about 105, 95,
90, 85, 80, and 75.degree. C. However, for wool fibers or other
protein-based fibers, the temperature can be less than about
75.degree. C. Optionally, magnesium sulfate can be included in the
scouring liquor.
[0091] FIG. 6 is an illustration of a method 600 for using oxygen
gas to displace the residual liquor from the fibers in the method
400 shown in FIG. 4. In method 600, the bleaching liquor 140 is
drained from the fiber processing Kier 120 by using a drain valve
610. Then, oxygen gas 110 is injected directly into the center
shaft 416 of the basket and diffuses through the fibers in the
fiber processing Kier 130.
[0092] FIG. 7 is an illustration of another method 700 for using
oxygen gas 110 to displace the residual liquor from the fibers in
the method 400 shown in FIG. 4. In method 700, the bleaching liquor
140 is also drained from the fiber processing Kier 120 using a
drain valve 610. The fiber processing Kier 120 has an oxygen
connection with a check valve 710 at the top of the fiber
processing Kier 120, at the bottom of the fiber processing Kier
(not shown), or on the liquor circulation pump 130 (not shown).
Thus, oxygen can be injected, and vented, into the system using
check valve 710.
[0093] FIG. 8 is an illustration of a control system 800 for
brightening of non-wood fibers in any kier system. The control
system 800 has an oxygen tank or other oxygen source for injecting
oxygen gas 110. A pressure control device 810 controls the pressure
of oxygen gas 110 from the primary source. An oxygen flow control
device 820 then controls the flow of oxygen into the system. A
liquor flow control device 840 after the liquor circulation pump
130 controls the flow of bleaching liquor 140 into the system. A
pressure relief safety valve 830 limits the maximum safe pressure
within the fiber processing Kier 120. A Kier pressure control 850
also moderates the pressure within the fiber processing Kier
120.
[0094] The scouring process described herein allows for both higher
(about 130.degree. C.) and lower temperature processes (about
100.degree. C.). During scouring, the system can be maintained at a
temperature in a range between about 95 and about 150.degree. C. In
another aspect, the system can be maintained at a temperature in a
range between about 110 and about 140.degree. C. during oxygen
exposure. Yet, in another aspect, the system can be maintained at a
temperature in a range between about 100 and about 130.degree. C.
during oxygen gas exposure. Still yet, in another aspect, the
system can be maintained at a temperature about or in any range
between about 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130,
135, 140, 145, and 150.degree. C.
[0095] During scouring, the system can be maintained under a
pressure in a range between about 1 and about 10 Bar. Maintaining
the system under pressure ensures that the oxygen will remain
dissolved in solution. In another aspect, the system is maintained
under a pressure in a range between about 2 and about 8 Bar. Yet in
another aspect, the system is maintained under a pressure in a
range between about 3 and about 6 Bar. Still yet, in another
aspect, the system is maintained under a pressure about or in any
range between about 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5,
7, 7.5, 8, 8.5, 9, 9.5, and 10 Bar.
[0096] The system is maintained under desired pressure and
temperature for a time sufficient to improve the brightness and
reduce the shive content of the fibers without damaging the fibers.
In one aspect, the fibers are scoured for a time in a range between
about 5 and about 180 minutes. In another aspect, the fibers are
scoured for a time in a range between about 30 and about 120
minutes. Yet, in another aspect, the fibers are scoured for a time
in a range between about 60 and about 180 minutes. Still yet, in
another aspect, the fibers are scoured for a time about or in any
range between about 5, 15, 30, 45, 60, 75, 90, 105, 120, 135, 150,
175, and 180 minutes.
[0097] At the end of the processing time, the system temperature is
cooled to below 100.degree. C. (the flash point), and the residual
gas is vented. Then, the spent liquor is drained from the system,
and the chamber cover is opened. Then rinse water can be added to
the fibers and circulated through the fibers with the circulation
pump 130. Then the fiber processing kier 120 is drained. The rinse
cycle can be repeated with fresh water or buffer as desired. The
fiber can then be centrifuged to remove any excess rinse water, and
the scoured fibers can be dried, carded, or subjected to additional
processing steps, such as bleaching.
[0098] The scoured fibers can be subsequently bleached by any
methods known in the art, for example peroxide bleaching and/or
reductive bleaching. One or more bleaching steps can be performed,
for example two peroxide bleaching steps or a peroxide bleaching
step and a reductive bleaching step. Reductive bleaching is only
effective after the fiber has been treated with oxygen gas.
Non-oxygen treated fibers will not be effective to decolorize in a
reductive stage.
[0099] Peroxide bleaching can include a peroxide compound and an
alkaline compound. Non-limiting examples of suitable peroxide
compounds include hydrogen peroxide, sodium peroxide, or both
hydrogen peroxide and sodium peroxide. Suitable alkaline compounds
include, but are not limited to, sodium hydroxide, potassium
hydroxide, calcium hydroxide, monoethanolamine, ammonia, or any
combination thereof. Alternatively, oxidative bleaching can be
performed using other methods, such as those using per-oxy
compounds, such as peracetic acid, peroxycarboxcylic acids, or
per-acids. Enzyme-catalyzed oxidative bleaching methods can also be
used.
[0100] Reductive bleaching stages can include reducing agents.
Non-limiting examples of suitable reducing agents include sodium
hydrosulfite, potassium hydrosulfite, sodium sulfite, potassium
sulfite, sodium sulfate, potassium sulfate, sodium bisulfite,
potassium bisulfite, sodium metasulfite, potassium metasulfite,
sodium borohydride, or any combination thereof.
[0101] In one aspect, oxygen may be used in a "degumming" process
with ammonia, for example, as disclosed in U.S. Pat. No. 7,892,397,
which is incorporated herein in its entirety by reference. As
disclosed in the '397 patent, cellulosic fibers are treated with a
degumming liquor comprising between about 5% to about 30% (v:v)
aqueous ammonia and between about 0.5% to 3% (on OD fiber) hydrogen
peroxide, at a temperature between about 50 to about 200.degree.
C., at a consistency of about 3:1 to about 20:1 liquor to solids
(v/w). The degumming liquor may further comprise 0% to 10% (on OD
fiber) of potassium hydroxide and 0% to 0.2% (on OD fibre) of
anthraquinone. Addition of oxygen gas in the ammonia-based
degumming process may increase fiber brightness and decrease shive
content.
[0102] The scoured and brightened fibers, before or after
bleaching, e.g., scoured and brightened and optionally bleached
bast fibers, can be used to form an article. Non-limiting examples
of the article include a yarn, a thread, a rope, a cord, or a
sliver. According to one or more aspects, the article is a yarn.
According to other aspects, the article is a thread. According to
some aspects, the article is a rope. In one or more aspects, the
article is a cord. In some aspects, the article is a sliver. The
scoured and brightened and optionally bleached bast fibers can be
used to form the articles. Methods for forming the articles, such
as yarns, thread, ropes, cords, and slivers, are known in the art,
and any suitable method or variation can be used.
[0103] The article can include one or more additives. Non-limiting
examples of additives include a lubricant, a finish, an antistatic
agent, or a combination thereof.
[0104] In addition to bast fibers, the article can include other
types of fibers. Non-limiting examples of other types of fibers
include synthetic fibers, polymeric fibers, thermoplastic fibers,
staple fibers, regenerated cellulose fibers, natural fibers, or a
combination thereof. According to one or more aspects, the natural
fibers are cotton fibers or wood pulp fibers. According to some
aspects, the polymeric fibers are polyester fibers.
[0105] The scoured and brightened and optionally bleached fibers,
e.g., brightened bast fibers, can be used to make nonwoven fabrics
and/or textiles according to conventional processes known to those
skilled in the art. The nonwoven fabrics, textiles, and other
products can include any amount of the fibers disclosed herein. The
fibers can be used to make fabrics, such as woven fabrics and knit
fabrics. For example, nonwoven fabrics, textiles, woven fabrics,
and knit fabrics can include about or in any range between about 5,
10, 15, 20, 25, 30, 25, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90,
95, and 100 wt. % of the fibers. The fabrics, such as woven fabrics
and knit fabrics, can include the scoured and brightened and
optionally bleached fibers, e.g., bast fibers, in the form of a
yarn, a thread, a rope, or a combination thereof. The fibers can be
woven or knit to form a woven or a knit fabric. Methods for
weaving, knitting, and like processes are known in the art, and any
suitable method or variation can be used to form the woven and knit
fabrics.
[0106] In addition to scoured and brightened and optionally
bleached bast fibers, the nonwoven fabrics, textiles, knit fabrics,
and woven fabrics can include other types of fibers. Non-limiting
examples of other types of fibers include synthetic fibers,
polymeric fibers, thermoplastic fibers, staple fibers, regenerated
cellulose fibers, natural fibers, or a combination thereof.
According to one or more aspects, the natural fibers are cotton
fibers. According to some aspects, the polymeric fibers are
polyester fibers.
[0107] The woven and knit fabrics can be or used in a variety of
applications. Non-limiting examples of applications include a wet
wiper, a dry wiper, an impregnated wiper, a sorbent, a clean room
wiper, a medical supply product, a personal protective fabric, an
automotive protective covering, a personal care article, a fluid
filtration product, a home furnishing product, a thermal insulation
product, an acoustic insulation product, an agricultural
application product, a landscaping application product, or a
geotextile application product.
[0108] Other non-limiting examples of products for the woven and
knit fabrics include a baby wipe, a cosmetic wipe, a perinea wipe,
a washcloth, a kitchen wipe, a bath wipe, a hard surface wipe, a
glass wipe, a mirror wipe, a leather wipe, an electronics wipe, a
lens wipe, a polishing wipe, a medical cleaning wipe, a
disinfecting wipe, an industrial wipe, a food service wipe, a
surgical drape, a surgical gown, a wound care product, a protective
coverall, a sleeve protector, a diaper, a feminine care article, a
nursing pad, an air filter, a water filter, an oil filter, a
furniture backing, or a surgical mask.
[0109] The scoured and brightened and optionally bleached fibers
can be used to make nonwoven fabrics and/or textiles according to
conventional processes known to those skilled in the art. The
nonwoven fabric of the present invention can be incorporated into a
variety of textiles and products. Non-limiting examples of products
include wipers (or wipes), such as wet wipers, dry wipers, or
impregnated wipers, which include personal care wipers, household
cleaning wipers, and dusting wipers. Personal care wipers can be
impregnated with, e.g., emollients, humectants, fragrances, and the
like. Household cleaning wipers or hard surface cleaning wipers can
be impregnated with, e.g., surfactants (for example, quaternary
amines), peroxides, chlorine, solvents, chelating agents,
antimicrobials, fragrances, and the like. Dusting wipers can be
impregnated with, e.g., oils.
[0110] Non-limiting examples of wipers include baby wipes, cosmetic
wipes, perinea wipes, disposable washcloths, household cleaning
wipes, such as kitchen wipes, bath wipes, or hard surface wipes,
disinfecting and germ removal wipes, specialty cleaning wipes, such
as glass wipes, mirror wipes, leather wipes, electronics wipes,
lens wipes, and polishing wipes, medical cleaning wipes,
disinfecting wipes, and the like. Additional examples of products
include sorbents, medical supplies, such as surgical drapes, gowns,
and wound care products, personal protective products for
industrial applications, such as protective coveralls, sleeve
protectors, and the like, protective coverings for automotive
applications, and protective coverings for marine applications. The
nonwoven fabric can be incorporated into absorbent cores, liners,
outer-covers, or other components of personal care articles, such
as diapers (baby or adult), training pants, feminine care articles
(pads and tampons) and nursing pads. Further, the nonwoven fabric
can be incorporated into fluid filtration products, such air
filters, water filters, and oil filters, home furnishings, such as
furniture backing, thermal and acoustic insulation products,
agricultural application products, landscaping application
products, and geotextile application products.
[0111] According to some aspects, the scoured and brightened and
optionally bleached fibers, e.g., bast fibers, are used to form an
article, such as an article of clothing. Non-limiting examples of
articles of clothing include a shirt, a blouse, a sweater, a
sweatshirt, a top, pants, trousers, a tank top, a leotard, a sport
specific clothing, a sock, an undergarment, a hat, a belt, a
jacket, a coat, a vest, a glove, a dress, a skirt, a scarf, a bib,
an apron, footware, or a combination thereof.
[0112] According to other aspects, the scoured and brightened and
optionally bleached fibers, e.g., brightened bast fibers, are used
to form an article, such as home furnishings. Non-limiting examples
of home furnishings include a drapery, a sheet, a blanket, a throw,
a comforter, a bedspread, a washcloth, a towel, a wall covering, a
chair covering, a sofa covering, a furniture upholstery, a seat
cover, a table cloth, a cushion covering, a pillow covering, or a
combination thereof.
[0113] In addition to the described bast fibers, the articles, such
as the article of clothing or home furnishing, can include other
types of fibers. Non-limiting examples of other types of suitable
fibers include synthetic fibers, polymeric fibers, thermoplastic
fibers, staple fibers, regenerated cellulose fibers, natural
fibers, or a combination thereof According to one or more aspects,
the natural fibers are cotton fibers. According to some aspects,
the polymeric fibers are polyester fibers.
[0114] The scoured and brightened and optionally bleached bast
fibers can be used to form a composite material. The composite
material includes the fibers and a matrix material. The bast fibers
can be randomly or substantially uniformly distributed throughout
the matrix material. The scoured and brightened and optionally
bleached fibers and matrix material are combined to form composite
materials. Methods for forming composite materials are known in the
art, and any suitable method or variation can be used.
[0115] The matrix material can be, for example, a thermoplastic
material or a thermoset material. Non-limiting examples of
thermoplastic materials include polypropylene, polyethylene,
polystyrene, polyvinyl chloride, poly(hydridocarbyne),
polyhydroxybutyrate, or a combination thereof. Non-limiting
examples of thermoset materials include an epoxy resin, a phenolic
resin, a polyurethane, a polyester, a vinyl resin, an acrylate
resin, or a combination thereof. The brightened bast fibers are in
the form of a nonwoven fabric or a woven fabric. The composite
material can be used in, for example, and not limited to, an
automobile part, an aviation part, a marine part, a home
furnishing, a building panel, or a combination thereof.
[0116] A nonwoven web of staple fibers can be formed by a
mechanical process known as carding as described in U.S. Pat. No.
797,749, which is incorporated herein in its entirety by reference.
The carding process can include an airstream component to randomize
the orientation of the staple fibers when they are collected on the
forming wire. A state of the art mechanical card, such as the
Tr{umlaut over (.upsilon.)}tzschler-Fliessner EWK-413 card, can run
staple fibers having significantly shorter length than the 38 mm
noted above. Older card designs may require longer fiber length to
achieve good formation and stable operation.
[0117] Another common dry web forming process is air-laid or
air-forming. This process employs only air flow, gravity, and
centripetal force to deposit a stream of fibers onto a moving
forming wire that conveys the fiber web to a web bonding process.
Air-laid processes are described in U.S. Pat. Nos. 4,014,635 and
4,640,810, both of which are incorporated herein in their entirety
by reference. Pulp-based air-formed nonwoven webs frequently
incorporate thermoplastic fibers that melt and bond the air-laid
web together when the air-formed web is passed through ovens.
[0118] Thermal bonding is also referred to as calendar bonding,
point bonding, or pattern bonding, can be used to bond a fiber web
to form a nonwoven fabric. Thermal bonding can also incorporate a
pattern into the fabric. Thermal bonding is described in PCT
International Publication No. WO/2005/025865, which is incorporated
herein by reference in its entirety. Thermal bonding requires
incorporation of thermoplastic fibers into the fiber web. Examples
of thermoplastic fibers are discussed above. In thermal bonding,
the fiber web is bonded under pressure by passing through heated
calendar rolls, which can be embossed with a pattern that transfers
to the surface of the fiber web. During thermal bonding, the
calendar rolls are heated to a temperature at least between the
glass transition temperature (T.sub.g) and the melting temperature
(T.sub.m) of the thermoplastic material.
[0119] Brightened fibers are formed into an unbounded web in the
wet or dry state. In one aspect, the web is formed by a method
employing a mechanical card. In another aspect, the web is formed
by a method employing a combination of a mechanical card and a
forced air stream. The dry web can be bonded by hydroentangling, or
hydroentanglement. In addition, the hydroentangled web can be
treated with an aqueous adhesive and exposed to heat to bond and
dry the web. Also, the dry web can be bonded by mechanical needle
punching and/or passing a heated air stream through the web.
Alternatively, the dry web can be bonded by applying an aqueous
adhesive to the unbounded web and exposing the web to heat.
[0120] Hydroentanglement, also known as spunlacing or spunbonding,
to form non-woven fabrics and substrates is well-known in the art.
Non-limiting examples of the hydroentangling process are described
in Canadian Patent No. 841,938 and U.S. Pat. Nos. 3,485,706 and
5,958,186. U.S. Pat. Nos. 3,485,706 and 5,958,186, respectively,
are incorporated herein in their entirety. Hydroentangling involves
forming a fiber web, either wet-laid or dry-laid, and thereafter
entangling the fibers by employing very fine water jets under high
pressure. For example, a plurality of rows of waterjets are
directed towards the fiber web which is disposed on a moving
support, such as a wire (mesh). Hydroentangling of the fibers
provides distinct hydroemboss patterns, which can create low fiber
count zones, facilitate water dispersion, and provide a three
dimensional structure. The entangled web is then dried.
[0121] A nonwoven fiber web of brightened fibers can be wet-laid or
foam-formed in the presence of a dispersion agent. The dispersion
agent can either be directly added to the fibers in the form of a
so-called "fiber finish" or it can be added to the water system in
a wet-laying or foam-forming process. The addition of a suitable
dispersion agent assists in providing a good formation, i.e,
substantially uniform fiber dispersion, of brightened fibers. The
dispersion agent can be of many different types which provide a
suitable dispersion effect on the brightened fibers or any mixture
of such brightened fibers. A non-limiting example of a dispersion
agent is a mixture of 75% bis(hydrogeneratedtallowaxyl)dimethyl
ammonium chloride and 25% propyleneglycol. The addition ought to be
within the range of 0.01-0.1 weight %.
[0122] During foam-forming the fibers are dispersed in a foamed
liquid containing a foam-forming surfactant and water, whereafter
the fiber dispersion is dewatered on a support, e.g., a wire
(mesh), in the same way as with wet-laying. After the fiber web is
formed, the fiber web is subjected to hydroentanglement with an
energy flux of about 23,000 foot-pounds per square inch per second
or higher. The hydroentanglement is carried out using conventional
techniques and with equipment supplied by machine manufacturers.
After hydroentanglement, the material is pressed and dried and,
optionally, wound onto a roll. The ready material is then converted
in a known way to a suitable format and is packed.
[0123] The nonwoven fabric described herein can be incorporated
into a laminate comprising the nonwoven fabric and a film.
Laminates can be used in a wide variety of applications, such
outer-covers for personal care products and absorbent articles, for
example diapers, training paints, incontinence garments, feminine
hygiene products, wound dressings, bandages, and the like.
[0124] To form a laminate, an adhesive is applied to a support
surface of the nonwoven fabric or a surface of the film. Examples
of suitable adhesives include sprayable latex, polyalphaolefin,
(commercially available as Rextac 2730 and Rextac 2723 from
Huntsman Polymers, Houston, Tex.), and ethylene vinyl acetate.
Additional commercially available adhesives include, but are not
limited to, those available from Bostik Findley, Inc., Wauwatosa,
Wis. Then, a film is fed onto the forming wire on top of the
nonwoven fabric. Before application to the nonwoven fabric, the
film is stretched as desired. The nonwoven fabric and film are
combined and compressed in a nip to form the laminate. Although not
required for pressure sensitive adhesives, the nip can be
maintained at a desired adhesive bonding temperature suitable for
the adhesive employed, e.g. heat activated adhesions. The laminate
can be cut, directed to a winder, or directed to further
processing.
[0125] In addition to applying a film to the nonwoven fabric,
another fabric can be bonded to the nonwoven fabric, which can be,
for example another nonwoven fabric or a woven fabric. The nonwoven
fabric can be a nonwoven fabric made in accordance with the present
invention. An adhesive can be applied to either the nonwoven fabric
or the other fabric before nipping to form the laminate.
[0126] The films used in laminates can include, but are not limited
to, polyethylene polymers, polyethylene copolymers, polypropylene
polymers, polypropylene copolymers, polyurethane polymers,
polyurethane copolymers, styrenebutadiene copolymers, or linear low
density polyethylene. Optionally, a breathable film, e.g. a film
comprising calcium carbonate, can be employed to form the laminate.
Generally, a film is "breathable" if it has a water vapor
transmission rate of at least 100 grams/square meter/24 hours,
which can be measured, for example, by the test method described in
U.S. Pat. No. 5,695,868, which is incorporated herein in its
entirety by reference. Breathable films, however, are not limited
to films comprising calcium carbonate. Breathable films can include
any filler. As used herein, "filler" is meant to include
particulates and other forms of materials which will not chemically
interfere with or adversely affect the film, but will be
substantially uniformly dispersed throughout the film. Generally,
fillers are in particulate form and spherical in shape, with
average diameters in the range between about 0.1 micrometers to
about 7 micrometers. Fillers include, but are not limited to,
organic and inorganic fillers.
[0127] Optionally, the scouring liquor or the fiber mixture
includes additives. Suitable additives include, but are not limited
to, chelants, magnesium sulfate, surfactants, wetting agents, pH
buffering agents, stabilizing additives, or any combination
thereof.
[0128] The optional one or more additives can be present in a range
between about 0.5 and about 5 wt. % based on the total weight of
the mixture of non-wood fibers. In another aspect, one or more
additives can be present in a range between about 1 and about 10
wt. %. Yet, in another aspect, one or more additives can be present
in a range between about 2 and about 6 wt. %. Still yet, in another
aspect, one or additives can be present in a range between about 3
and about 5 wt. %. In one aspect, the mixture of non-wood fibers
can include one or more additives about or in any range between
about 0.1, 0.2, 0.5, 0.7, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
13, 14, 15, 16, 17, 18, 19, and 20 wt. %.
[0129] Suitable chelants include any metal sequestrant.
Non-limiting examples of chelants include ethylenediamine-N,
N'-disuccinic acid (EDDS) or the alkali metal, alkaline earth
metal, ammonium, or substituted ammonium salts thereof, or mixtures
thereof. Suitable EDDS compounds include the free acid form and the
sodium or magnesium salt thereof. Examples of sodium salts of EDDS
include Na.sub.2EDDS and Na.sub.4EDDS. Examples of such magnesium
salts of EDDS include MgEDDS and Mg.sub.2EDDS. Other chelants
include the organic phosphonates, including amino alkylene
poly(alkylene phosphonate), alkali metal ethane-1-hydroxy
diphosphonates, nitrile-trimethylene phosphonates, ethylene diamine
tetra methylene phosphonates, and diethylene triamine penta
methylene phosphonates. The phosphonate compounds can be present
either in their acid form or as a complex of either an alkali or
alkaline metal ion, the molar ratio of the metal ion to phosphonate
compound being at least 1:1. Other suitable chelants include amino
polycarboxylate chelants such as EDTA.
[0130] Suitable wetting agents and/or cleaning agents include, but
are not limited to, detergents and nonionic, amphoteric, and
anionic surfactants, including amino acid-based surfactants. Amino
acid-based surfactant systems, such as those derived from amino
acids L-glutamic acid and other natural fatty acids, offer pH
compatibility to human skin and good cleansing power, while being
relatively safe and providing improved tactile and moisturization
properties compared to other anionic surfactants.
[0131] Suitable buffering systems include any buffering agents that
assist the buffering system in reducing pH changes. Illustrative
classes of buffering agents include, but are not limited to, a salt
of a Group IA metal including, for example, a bicarbonate salt of a
Group IA metal, a carbonate salt of a Group IA metal, an alkaline
or alkali earth metal buffering agent, an aluminum buffering agent,
a calcium buffering agent, a sodium buffering agent, a magnesium
buffering agent, or any combination thereof. Suitable buffering
agents include carbonates, phosphates, bicarbonates, citrates,
borates, acetates, phthalates, tartrates, succinates of any of the
foregoing, for example sodium or potassium phosphate, citrate,
borate, acetate, bicarbonate and carbonate, or any combination
thereof. Non-limiting examples of suitable buffering agents include
aluminum-magnesium hydroxide, aluminum glycinate, calcium acetate,
calcium bicarbonate, calcium borate, calcium carbonate, calcium
citrate, calcium gluconate, calcium glycerophosphate, calcium
hydroxide, calcium lactate, calcium phthalate, calcium phosphate,
calcium succinate, calcium tartrate, dibasic sodium phosphate,
dipotassium hydrogen phosphate, dipotassium phosphate, di sodium
hydrogen phosphate, di sodium succinate, dry aluminum hydroxide
gel, magnesium acetate, magnesium aluminate, magnesium borate,
magnesium bicarbonate, magnesium carbonate, magnesium citrate,
magnesium gluconate, magnesium hydroxide, magnesium lactate,
magnesium metasilicate aluminate, magnesium oxide, magnesium
phthalate, magnesium phosphate, magnesium silicate, magnesium
succinate, magnesium tartrate, potassium acetate, potassium
carbonate, potassium bicarbonate, potassium borate, potassium
citrate, potassium metaphosphate, potassium phthalate, potassium
phosphate, potassium polyphosphate, potassium pyrophosphate,
potassium succinate, potassium tartrate, sodium acetate, sodium
bicarbonate, sodium borate, sodium carbonate, sodium citrate,
sodium gluconate, sodium hydrogen phosphate, sodium hydroxide,
sodium lactate, sodium phthalate, sodium phosphate, sodium
polyphosphate, sodium pyrophosphate, sodium sesquicarbonate, sodium
succinate, sodium tartrate, sodium tripolyphosphate, synthetic
hydrotalcite, tetrapotassium pyrophosphate, tetrasodium
pyrophosphate, tripotassium phosphate, trisodium phosphate,
trometamol, or any combination thereof.
EXAMPLES
[0132] In Examples 1-6, the fiber brightness provided by
conventional scouring processes was compared to that provided by
the inventive scouring process disclosed herein. In each example,
about 100 g dry decorticated fiber was mixed with water and
subsequently centrifuged to remove most of the remaining water. The
fiber was packed into the stainless steel perforated basket of a
fiber processing kier (Colortec Sample Dyeing Machine, commercially
available from Roaches International LTD, West Yorkshire, England).
The basket was equipped with a central perforated shaft to enable
scouring liquor to be circulated radially through the fibers. The
top of the basket was covered with a stainless steel plate, and
then the basket was placed into the Colortec chamber.
[0133] An aqueous liquor of the desired chemicals was prepared and
added to the chamber. The liquor was pre-heated to 60-70.degree. C.
to accelerate the heat-up cycle. The cover of the chamber was
closed, and the circulation pump was started. The liquor was set to
circulate from the inside of the basket to the outside of the
basket. The system was programmed to heat the liquor to the desired
(indicated) treatment temperature and then to hold the system at
this temperature for the desired treatment time. Periodically, the
liquor flow was reversed for about one minute to minimize any
channeling in the fiber.
[0134] When using oxygen, the oxygen gas was added at the inlet
side of the circulation pump (although it could have been added at
any point in the system). The circulation pump aided in dissolving
the oxygen charge. Further, the oxygen concentration was controlled
by adjusting the partial pressure. The oxygen was vented one or
more times to flush air from the system and to ensure the maximum
possible dissolved oxygen concentration.
[0135] At the end of the processing time, the heater was turned
off, the system was cooled to below 100.degree. C. (the flash
point), and the residual gas was vented. Then, the spent liquor was
drained from the system, and the chamber cover was opened. A water
rinse was added to the chamber, and the rinse water was circulated
(about 10-20 minutes) and then drained. The rinse cycle was
repeated 2 to 4 times with fresh rinse water. The chamber was then
drained, opened, and the basket was removed from the machine. The
fiber was centrifuged to remove any excess rinse water. The scoured
fiber was then dried, carded, or subjected to additional processing
steps, such as bleaching.
Comparative Example 1
[0136] A sample of flax fiber (Pamplico Decorticated Fax (PDF),
commercially available from CRAiLAR Technologies, Inc. (Victoria,
B.C, Canada), was scoured under standard conditions (no oxygen or
magnesium compounds). Samples of CRAiLAR Treated Pamplico
Decorticated Flax (CCPDF1-4) are shown in Table 1, which were run
to generate a caustic (NaOH) dose curve with increasing percentages
of NaOH. The system was run with a 30 minute retention at
130.degree. C. with 1% on pulp ("OP") of Ultrascour JD (Dacar
Chemical Company, Pittsburgh, Pa.), a surfactant/wetting agent,
added to the liquor. After scouring, the fiber was rinsed four
times at 80.degree. C. Rinses 1, 3, and 4 were with water, and
rinse 2 was with a solution of water including 2% OP sodium
citrate.
TABLE-US-00001 TABLE 1 Comparative fiber scouring TAPPI Weight NaOH
525 CIE loss Sample % owf Brightness L* a* b* Whiteness (%) PDF
(blend) na 18.5 58.4 3.4 15.3 -75.5 n/a CCPDF4 7.5 25.4 63.5 2.3
11.0 -36.8 21.8 CCPDF1 8 27.0 64.7 2.1 10.6 -31.9 23.0 CCPDF2 10
26.1 64.1 2.2 10.8 -34.7 23.1 CCPDF3 12 26.3 64.2 2.0 10.8 -34.5
23.6
[0137] As shown in Table 1, the untreated PDF had a TAPPI
brightness of 18.5. The scoured fiber samples had a brightness
between 25.4 and 27.0, with a yield loss between 21.8 and
23.6%.
Example 2
[0138] The next set of samples (Table 2) was run under the
inventive scouring conditions (with addition of oxygen gas,
magnesium sulfate, and oxygen gas+magnesium sulfate). The oxygen
gas was added to the system by the following steps: 1) the system
pressure was increased to 2 Bar with oxygen once a temperature of
98.degree. C. was reached; 2) the oxygen pressure was released
after 2 minutes; 3) the temperature was maintained at 130.degree.
C. once reached; 4) after 15 minutes at 130.degree. C., the system
was pressurized to 4 Bar with oxygen (2 Bar partial pressure); and
5) the sample was then maintained under the system conditions for a
15 minute retention time at 130.degree. C.
TABLE-US-00002 TABLE 2 Scouring process with oxygen and magnesium
sulfate % owf TAPPI 525 CIE Weight Sample NaOH MgSO4 Oxygen
Brightness L* a* b* Whiteness loss (%) CCPDF5 10 Yes 29.3 66.8 2.4
10.6 -27.5 25.2 CCPDF6 10 0.5 Yes 32.4 70.8 2.8 12.9 -32.1 24.3
CCPDF7 10 0.5 Yes 31.0 68.8 2.7 11.5 -28.7 25.4 CCPDF9 10 0.5 No
25.2 63.1 2.2 10.6 -35.6 23.5 CCPDF 6/7 10 0.5 Yes 33.9 71.7 2.8
12.4 -27.5 24.9 CCPDF2 10 No 26.1 64.1 2.2 10.8 -34.7 23.1
[0139] As shown in Table 2, the oxygen samples demonstrated a
significant increase in brightness over the non-oxygen scoured
samples. Further, the addition of magnesium to the oxygen scour
enhanced the brightness gain compared to oxygen alone. Sample
CCPDF9 was run with magnesium sulfate (no oxygen), and did not show
a significant improvement over the control (CCPDF2) sample.
Example 3
[0140] Table 3 compares the strength, micronair, and trash
properties of the scoured fibers in Comparative Example 1 and
Example 2. Strength is a tensile measurement and has units of
gram/tex. Micronair is a measure of the fiber "fineness." Trash is
percent (%) of non-fiber debris (shives and other materials).
TABLE-US-00003 TABLE 3 Comparison of fiber physical properties %
owf Sample NaOH MgSO4 Oxygen Strength micronair trash PDF 45.4 9.3
14.8 AV 38.4 8.9 8.6 CCPDF1 8 No 31.7 8.6 7.6 CCPDF2 10 No 31.5 8.4
7.4 CCPDF3 12 No 31.9 8.6 8.6 CCPDF4 7.5 No 32.3 8.5 9.0 CCPDF5 10
Yes 43.2 9.4 8.8 CCPDF6 10 0.5 Yes 42.3 9.1 9.2 CCPDF7 10 0.5 Yes
34.5 8.6 8.0 CCPDF9 10 0.5 No 37.2 9.3 10.7
Example 4
[0141] Table 4 compares brightness after scouring, single stage
peroxide bleaching followed by a rinse (stage 1) or a second
hydrogen peroxide bleaching stage (stage 2). The residual peroxide
(H.sub.2O.sub.2) remaining indicates less peroxide is needed to
achieve the same brightness. In Table 4, L* is the whiteness, and
a* and b* are the colors red-green and blue-yellow, respectively.
A* and b* values close to 0 indicate very low color/no color.
TABLE-US-00004 TABLE 4 Magnesium hydroxide substitution Alkali % of
Total Scour Peroxide--Stage 1 Final ID Mg(OH)2 NaOH Oxygen
Brightness L* a* b* Brightness L* a* b* pH CPF 25.9 64.3 1.3 11.5
CPF101 0 0 24.1 61.0 1.1 8.6 39.6 78.1 0.5 15.9 9.7 CPF102 100 0
26.9 63.4 0.7 8.0 43.1 79.9 0.3 14.7 10.2 CPF103 50 50 31.7 67.6
0.5 8.1 55.6 89.1 -0.2 12.0 10.9 CPF104 25 75 32.9 68.8 0.6 8.4
56.6 86.4 -0.2 11.6 11.2 CPF105 0 100 29.2 65.6 0.7 8.4 58.7 87.7
-0.2 11.8 10.6 CPF201 0 0 X 25.2 62.7 1.8 9.6 44.2 81.1 -0.1 15.6
9.6 CPF202 100 0 X 30.8 67.6 1.1 9.4 36.0 75.9 1.0 16.7 10.6 CPF203
50 50 X 40.0 75.1 1.1 10.1 62.2 88.9 -0.6 10.6 10.6 CPF204 25 75 X
45.3 79.2 1.0 10.9 59.4 86.8 -0.1 9.5 11.1 CPF205 0 100 X 41.4 76.9
1.2 11.3 64.3 89.1 0.9 8.9 10.7 H2O2 Peroxide--Stage 2 Final H2O2
Brightness Gain ID Res g/l Brightness L* a* b* pH Res g/l Scour P
Stage P/P Stage Total CPF CPF101 0.85 50.94 85.03 -0.37 15 9.97 2
-1.8 15.6 11.3 25.0 CPF102 0.54 48.38 83.65 -0.22 15.35 9.81 2 1.0
16.3 5.3 22.5 CPF103 0.17 67.17 91.28 -0.81 10.26 9.43 1.6 5.8 23.9
11.6 41.3 CPF104 0.14 67.32 91.13 -0.91 9.87 9.59 1.7 7.0 23.8 10.7
41.4 CPF105 0.78 69.71 92.05 -0.6 9.35 9.95 1.7 3.3 29.6 11.0 43.8
CPF201 0.71 64.21 91.26 -1.17 13 10.13 2.5 -0.7 19.0 20.1 38.3
CPF202 0.61 50.69 84.81 -0.18 14.9 9.75 1.97 4.9 5.1 14.7 24.8
CPF203 0.10 68.05 91.63 -0.64 10.08 14.1 22.3 5.8 42.2 CPF204 0.20
70.35 91.84 -0.41 8.43 9.95 2 19.4 14.1 11.0 44.5 CPF205 0.65 72.73
92.33 -0.34 7.21 9.47 1.8 15.5 23.0 8.4 46.8
[0142] Each peroxide bleaching stage was performed using a modified
"spinner" method. In this method, about 30 g oven dry (OD) fiber
was added to a 4 L beaker. Distilled water and the indicated
chemicals were added to bring the pulp to about an 8% consistency.
The beakers were then placed in a 190.degree. F. water bath about
80% submerged. Instead of continuously agitating the fibers with a
motorized spinner, the samples were manually mixed (using a spoon)
at approximately 10 minute intervals throughout a 180 minute
bleaching duration. A small amount of sodium silicate, 0.2 wt. % on
pulp, was also added to the samples to help stabilize hydrogen
peroxide.
[0143] Experiments were conducted to assess the impact of oxygen
gas on the scour process, as well as the interaction between
magnesium hydroxide and sodium hydroxide at high substitution
rates. In the first set of samples (CPF101-105) (Table 4), a curve
for substitution of sodium hydroxide for magnesium hydroxide
without oxygen was generated. Samples CPF102-105 were run with a
total alkali dose of 10% OP (equal alkali basis. The curve
indicated that magnesium hydroxide can be substituted for sodium
hydroxide up to about 50% (equal alkali basis) but does not result
in significant improvement in brightness (compare brightness
results of 25.9 to 31.7).
[0144] The second set of samples (FPR202-205) was run with the same
chemical doses except with added oxygen gas in the scour (Table 4).
The same trend in scour and final peroxide brightness was seen as
above, with magnesium substitution up to about 50%. The addition of
oxygen gas also resulted in a 1.1 to 12.4 increase in brightness
and up to 13.3 points higher in brightness following two-stage
peroxide bleach.
[0145] Samples CPF101 and CPF201 were scoured with no alkali
addition (only water). Further, CPF101 was run without oxygen and
CPF201 was run with oxygen. While the neutral pH (non-alkali)
scours did not perform as well as those with alkali, an improvement
of over 13 points in final brightness was observed in the sample
with oxygen (CPF201) compared to the sample without oxygen
(CPF101). This result indicates that addition of oxygen gas
provides a significant reduction in alkali required to effectively
scour fibers, while at the same time generating a competitive
brightness result.
[0146] As shown in Table 4, while oxygen scouring resulted in
fibers with a brightness of 25.2 to 41.1, a single subsequent
peroxide bleaching process further increased the brightness to 44.2
to 64.3, and two subsequent peroxide bleaching processes even
further increased the brightness to 64.21 to 72.73.
Example 5
[0147] Experiments were conducted to assess the impact of adding
oxygen gas at the end of the scouring process, after draining the
scouring liquor from the kier (in contrast to Examples 1-4 where
oxygen gas was introduced into the scour liquor). It was
hypothesized that oxygen could be introduced directly into the head
space of the kier, which could be done after chemical pectin
removal (and with the kier drained of liquor). The oxygen could
then permeate the fiber mat and react with the chromophores and
shive.
[0148] Sample CPF500 was prepared similar to CPF101 in Example 4
and run with only water in the kier (i.e., no alkali addition), and
sample CPF505 had 10% sodium hydroxide OP added (Table 4). At the
end of the scour process, the kier was drained and oxygen gas was
rapidly added to achieve a 4 Bar pressure (about 3 Bar oxygen
partial pressure). The oxygen gas was added so that most of the
oxygen entered the kier from the inside perforated tube, which
resulted in displacement of much of the residual liquor. The oxygen
gas was then allowed to react with the fiber for 10 minutes before
being vented. During this time, the fiber lost temperature (to
approximately 100.degree. C.) due to the loss of circulation
heating. The oxygen gas was then vented, and the fiber was rinsed
as described above.
TABLE-US-00005 TABLE 5 Oxygen displacement after draining the kier
Alkali % of Total Scour Peroxide--Stage 1 ID Description Mg(OH)2
NaOH Oxygen Brightness L* a* b* Brightness L* a* b* CPF Start 25.9
64.3 1.3 11.5 CPF500 O2 No Liquor 0 0 X 33.3 68.9 0.5 8.0 51.2 85.2
-0.4 15.0 CPF505 O2 No Liquor 0 100 X 44.1 78.8 0.9 11.5 60.5 87.9
-0.3 10.3 CPF201 Water Only 0 0 X 25.2 62.7 1.8 9.6 44.2 81.1 -0.1
15.6 Final H2O2 Peroxide--Stage 2 Final H2O2 Brightness Gain ID pH
Res g/l Brightness L* a* b* pH Res g/l Scour P Stage P/P Stage
Total CPF CPF500 9.3 2.90 67.1 90.7 -1.62 9.37 9.79 3.1 7.4 17.8
15.9 41.2 CPF505 10.0 2.80 78.51 94.46 -0.7 6.27 9.76 2.6 18.2 16.4
18.0 52.6 CPF201 9.6 0.71 64.21 91.26 -1.17 13 10.13 2.5 -0.7 19.0
20.1 38.3
[0149] As a result of the additional liquor displacement from the
oxygen gas, the color of the rinses was noticeably reduced compared
to a conventional scour. These results additionally indicate that
gas (air or other inert gas) displacement at the end of a scour
and/or rinse or bleach stage is beneficial in increasing the
efficiency of the subsequent stage. Further, this process reduces
the number of rinse stages, the rinse water volume required, and
increases the efficiency of the next stage due to the lower
carryover of residual chemicals.
[0150] Compared to CPF101 (no alkali or oxygen) and CPF201 (no
alkali with oxygen), sample CPF500 (also without alkali) had a 9.2
and 8.1 higher brightness after the scour. When oxygen was
introduced into the kier after scour, the first stage bleached
brightness was 7 points higher than when oxygen introduced into the
liquor (CPR201), and the second stage bleached brightness was 2.9
points higher. Further, the significantly higher peroxide residual
in both stages reflected higher peroxide bleaching efficiency,
which demonstrated utility in reducing the required peroxide
dose.
[0151] Sample CPF505 achieved a 44.1 scour brightness, which was
higher than any of the examples. After two stage peroxide
bleaching, CPF505 achieved a 78.5 final brightness. CPF205, with
oxygen addition in the liquor during the scour, achieved a final
brightness of 72.7, which was 5.8 points lower under similar
processing conditions. There also was a significant increase in
peroxide residual for both bleaching stages, which again supported
the ability to reduce the peroxide charge and chemical cost.
Example 6
[0152] A conventionally scoured flax fiber sample was scoured and
dried. The sample (BJT) had an untreated brightness of 26.4 (Table
6). The fiber was then soaked at 90.degree. C. to determine the
impact of citrate on the subsequent peroxide bleaching stage. A
control soak, with water only, demonstrated a 66.5 brightness after
standard peroxide bleaching. However, the citrate soaked samples
showed improved brightness responses of 71.5 and 71.7 after soaking
in tri-sodium citrate or citric acid.
TABLE-US-00006 TABLE 6 Citrate effect on brightness CIE TAPPI
Sample Pre-Treatment Bleaching L* a* b* Whiteness Brightness BJT
untreated untreated 63.4 2.4 9.0 -24.5 26.4 BJT-BLK-B9 deionised
water 16 hrs peroxide bleach 90 C. 89.7 -0.2 8.4 35.8 66.5
BJT-CIT-B9 citric acid 16 hrs peroxide bleach 90 C. 91.6 -0.4 7.1
46.4 71.7 BJT-TSC-B9 trisodium citrate 16 hrs peroxide bleach 90 C.
91.7 -0.3 7.5 45.1 71.5
Example 7
Commercial Flax
[0153] For comparison, a sample bleached flax fiber was acquired
from Flaxcraft, Inc. (Cresskill, N.J.). The fiber optical
properties were determined using the standard test on the MacBeth
3100 instrument. The fiber demonstrated a brightness of 67.44. The
properties of the starting flax fiber sample, which is an example
of a commercial flax fiber, is shown in Table 7 below for
comparison purposes.
TABLE-US-00007 TABLE 7 Starting sample of commercial bleached flax
fibers Sample L* a* b* Brightness Whiteness SANETOW 24GR 90.41
-0.96 8.45 67.44 36.44
Inventive Flax Scouring Procedures
[0154] In the following examples, flax processing (scouring
decorticated and cleaned flax fiber) was performed according to the
following standard procedure: [0155] 1. A sample of flax fiber was
weighed out, wetted, and packed into the kier basket [0156] 2. The
cover was clamped onto the basket, the basket was placed into the
kier. The kier was then sealed. [0157] 3. The process water was
preheated to 50.degree. C., and NaOH, wetting agent (Scourer JD),
and sequestering agent (SEQ600) was mixed with the water to form a
scouring liquor. [0158] 4. The kier was filled with the scouring
liquor, and the external, and the internal circulation pumps were
started. [0159] 5. The temperature was increased at a rate of
3.degree. C. per minute using non-contact steam. [0160] 6. Once the
temperature reached 130.degree. C., the temperature was held for 45
minutes. [0161] 7. The kier was cooled to 90.degree. C. by
circulating liquor through a non-contact heat exchanger. [0162] 8.
The circulation pumps were stopped, and the kier was drained.
[0163] One or more rinse cycles were then completed. The rinse
procedure steps were as follows: [0164] 1. Clean rinse water was
heated to 50.degree. C. [0165] 2. The kier was filled with the
rinse water, and the circulation pumps were started. [0166] 3.
After about 5 minutes, the pumps were stopped, and the kier was
drained.
[0167] After rinsing, the fiber could then be bleached. Typically,
the fiber remained in the kier for bleaching so that the
scour+rinse+bleach+rinse procedure was carried out as a contiguous
process. The kier was not opened to remove a small sample of fiber
between stages so the process could be monitored.
[0168] The standard peroxide bleaching procedure was performed as
follows: [0169] 1. Clean water was added to the side tank and
heated to 50.degree. C. with non-contact steam. [0170] 2. NaOH,
H.sub.2O.sub.2, and a silicate-based stabilizer was added to the
water. [0171] 3. The circulation pumps were started, and the kier
was filled with the bleaching liquor. [0172] 4. The temperature was
raised by 2-3.degree. C. per minute using non-contact steam. [0173]
5. Once the bleaching temperature was achieved, typically
90.degree. C. to 110.degree. C., the temperature was held for 20 to
60 minutes. [0174] 6. Optionally, after the initial hold time, the
temperature could be increased by 10 to 30.degree. C. for an
additional 10 to 30 minutes to complete the brightening reactions.
[0175] 7. The kier was cooled using non-contact cooling water in a
heat exchanger. [0176] 8. The circulation pump(s) were stopped, and
the kier was drained. [0177] 9. 1 to 3 rinses were performed.
[0178] 10. Optionally, a mild acid, such as acetic acid, was added
to the rinse water to reduce the fiber pH to near neutral (about
7).
[0179] After the final rinsing, the kier was opened, and the basket
was removed. Typically, the basket was placed in a centrifuge and
spun for 5 to 20 minutes to remove as much water as possible. The
fiber could then be removed from the basket and dried and baled as
necessary for the intended end product use.
[0180] The first oxygen scour procedure (1) was performed as
follows: [0181] 1. A sample of flax fiber was weighed out, wetted,
and packed into the kier basket. [0182] 2. The cover was clamped
onto the basket, the basked was placed into the kier. The kier was
then sealed. [0183] 3. The process water was preheated to
50.degree. C., and NaOH, wetting agent (Scourer JD), and
sequestering agent (SEQ600) was mixed with the water to form a
scouring liquor. [0184] 4. The kier was filled with the scouring
liquor, and the external and internal circulation pumps were
started. [0185] 5. The external circulation valve was closed to
seal the kier, and oxygen gas was added to the bottom of the kier
so that the gas was drawn into the internal circulation pump.
[0186] 6. The kier was pressurized to about 4 Bar with oxygen, and
additional oxygen was added to maintain 4 Bar of pressure through
the heating and temperature hold time. The kier was vented as
needed above 100.degree. C. to prevent over pressurization above
4.5 Bar. As steam pressure was produced, the partial pressure of
oxygen was allowed to decrease to maintain consistent pressure.
[0187] 7. The temperature was increased at a rate of 3.degree. C.
per minute using non-contact steam. [0188] 8. Once the temperature
reached 130.degree. C., the temperature was held for 45 minutes.
[0189] 9. Prior to cooling, the oxygen gas was shut off, and the
kier external circulation valve was slowly opened to relieve the
oxygen pressure. [0190] 10. The kier was cooled to 90.degree. C. by
circulating liquor through a non-contact heat exchanger. [0191] 11.
The circulation pumps were stopped, and the kier was drained. The
total time with oxygen present will be specified in the example
descriptions below.
[0192] The second oxygen procedure (2) was performed as follows:
[0193] 1. A sample of flax fiber was weighed out, wetted, and
packed into the kier basket. [0194] 2. The cover was clamped onto
the basket, the basked was placed into the kier. The kier was then
sealed. [0195] 3. The process water was preheated to 50.degree. C.,
and NaOH, wetting agent (Scourer JD), and sequestering agent
(SEQ600) was mixed with the water to form a scouring liquor. [0196]
4. The kier was filled with the scouring liquor and the external
and internal circulation pumps were started. [0197] 5. The external
circulation valve was closed to develop a kier pressure of 2-3 Bar,
while maintaining a small external circulation of liquor. The
circulation rate was about 10% of the wide open flow. [0198] 6.
Oxygen gas was added to the bottom of the kier so that the gas was
drawn into the internal circulation pump. The gas flow was
regulated to maintain a level of dissolved oxygen in the liquor,
without allowing excessive un-dissolved oxygen gas bubbles to form
and discharge from the kier. [0199] 7. The kier pressure was
maintained at 2-3 Bar by regulating the oxygen flow and external
circulation flow as the temperature was ramped up and held. [0200]
8. The temperature was increased at a rate of 3.degree. C. per
minute using non-contact steam. [0201] 9. Once the temperature
reached 130.degree. C., the temperature was held for 45 minutes.
[0202] 10. Prior to cooling, the oxygen gas was shut off, and the
kier external circulation valve was slowly opened to relieve the
oxygen pressure. [0203] 11. The kier was cooled to 90.degree. C. by
circulating liquor through a non-contact heat exchanger. [0204] 12.
The circulation pumps were stopped, and the kier was drained.
Example 8
[0205] A bale of decorticated and cleaned flax was selected to run
a series of pilot scale trials. Scouring was performed using this
"standard" bale of flax to provide a uniform starting material. The
optical properties of the fiber were determined using a Datacolor
Spectraflash SF600 Plus-CT reflectance spectrophotometer using
ColorTools QC software, D65 illuminant at a 10.degree. observer
condition.
TABLE-US-00008 TABLE 8 Optical properties of starting flax fibers
CIE TAPPI Whiteness 525 L* a* b* .DELTA.E Index Brightness 57.12
2.25 12.16 0 -57.81 18.86
[0206] Scouring was performed in a pilot kier system, manufactured
by Callebaut De Blicquy S.A. (Brussels, Belgium). The system had a
kier capacity of 200 liters and a basket capable of holding 10-20
kg OD fiber. A 12 kg (OD) sample of the starting flax in Table 8
was placed in the kier basket and scoured using the standard
(non-oxygen) scouring process described in above in Example 7. The
scour was completed using 12% NaOH, 1.0% Scourer JD, and 0.25%
SEQ600. After scouring and rinsing, the flax had the following
optical properties shown in Table 9:
TABLE-US-00009 TABLE 9 Flax fibers scoured without oxygen CIE TAPPI
Whiteness 525 L* a* b* .DELTA.E Index Brightness 60.29 1.7 8.61
5.04 -28.04 23.51
Example 9
[0207] A 12 kg (OD) sample of the Table 8 starting flax was placed
in the kier basket and scoured using the oxygen scour procedure (2)
process described above in Example 7. The scour was completed using
12% NaOH, 1.0% Scourer JD, and 0.25% SEQ600. Oxygen addition was
started when the kier reached 70.degree. C. and was maintained
until the final 5 minutes of retention at 130.degree. C. Based on
the oxygen tank weight prior to the start of the scour and the
weight after completion of the scour, total oxygen applied was
1.4%. Table 10 provides the optical properties of the fiber after
scouring:
TABLE-US-00010 TABLE 10 Optical properties after scouring with
oxygen scour procedure (2) CIE TAPPI Whiteness 525 L* a* b*
.DELTA.E Index Brightness 77.06 1.92 11.27 20.15 -8.99 41.99
Example 10
[0208] A 12 kg (OD) sample of the Table 8 starting flax was placed
in the kier basket and scoured using the oxygen scour procedure (2)
process. The scour was completed using 12% NaOH, 1.0% Scourer JD,
and 0.25% SEQ600. 0.5% magnesium sulfate was also added to the
scour liquor. Oxygen addition was started when the kier reached
70.degree. C. and maintained until the final 5 minutes of retention
at 130.degree. C. The optical properties of the fiber after
scouring are shown in Table 11 below.
TABLE-US-00011 TABLE 11 Optical properties after scouring with
oxygen scour procedure (2) and magnesium sulfate CIE TAPPI
Whiteness 525 L* a* b* .DELTA.E Index Brightness 73.94 1.92 11.03
17.12 -14.78 37.75
Example 11
[0209] After scouring in Examples 9 and 10, a small sample of
liquor was collected from the kier at intervals and tested for
total dissolved solids (TDS) and alkalinity (NaOH g/l). The
increase in solids (pectin, lignin, waxes, and other undesirable
compounds) in the liquor is an indication of the progression of the
scour, as scouring is performed to remove these solids from the
fibers.
[0210] The graph in FIG. 9 shows the increase in liquor solids as a
function of the time elapsed, as well as of the temperature of the
kier at each sample point for Examples 9 and 10. The standard
non-oxygen scour showed very little change in the TDS until a
temperature in excess of 110.degree. C. was achieved (Example 8).
In contrast, the oxygen reinforced scours in Examples 9 and 10
showed an immediate steep rise in TDS followed by a slower rise
above 120.degree. C. (see FIG. 9). The curve also showed a much
higher level of extracted materials for the oxygen scour. Oxygen
scour achieved a solids level at 20 minutes time and below about
100.degree. C., compared to the traditional scour which required 80
minutes total time, including 45 minutes at 130.degree. C., to
achieve the same result.
[0211] The graph in FIG. 10 shows the liquor caustic (NaOH)
concentration for Examples 9 and 10. As shown, very little NaOH was
consumed for both examples in the initial 15 minutes. After this
time, however, the caustic concentration dropped for both examples.
Example 9 dropped more sharply, with a much higher amount of
caustic being consumed in the scour.
Example 12
[0212] A 14 kg (OD) sample of the starting flax of Table 8 was
placed in the kier basket and scoured using the standard
(non-oxygen) scour procedure. After scouring and rinsing, the flax
achieved a 24.84 TAPPI brightness as shown in Table 12 below.
TABLE-US-00012 TABLE 12 Flax fibers scoured without oxygen CIE
TAPPI Whiteness 525 L* a* b* .DELTA.E Index Brightness 62.62 2.08
10.47 0 -35.37 24.84
Example 13
[0213] A 14 kg (OD) sample of the starting flax of Table 8 was
placed in the kier basket and scoured using the oxygen scour
procedure (2) described in Example 7. After scouring and rinsing,
the fiber achieved a 27.31 TAPPI brightness as shown in Table 13
below.
TABLE-US-00013 TABLE 13 Optical properties after scouring with
oxygen scour procedure (2) CIE TAPPI Whiteness 525 L* a* b*
.DELTA.E Index Brightness 65.33 2.45 11.13 2.74 -33.87 27.31
Example 14
[0214] Based on the unexpected acceleration and improvement in the
scouring process in the above examples, a low temperature scouring
process was developed to take advantage of the utilization of
oxygen gas to reduce the energy cost and safety of the scouring
process. It is also desirable to avoid heating the fibers to
excessive temperatures, as high temperatures tend to damage the
fibers and cellulose which results in lower tensile strength and
reduced commercial value. In addition, NaOH was added after the
oxygen gas was applied to the fibers to avoid any potential alkali
darkening.
[0215] The third oxygen scour procedure (3) was performed as
follows: [0216] 1. A sample of flax fiber was weighed out, wetted,
and packed into the kier basket. [0217] 2. The cover was clamped
onto the basket, and the basked placed into the kier. The kier was
then sealed. [0218] 3. The process water was preheated to
50.degree. C., the kier was filled with the scouring water, and the
external and internal circulation pumps were started. [0219] 4. The
external circulation valve was closed to develop a kier pressure of
2-3 Bar, while maintaining a small external circulation of liquor.
The circulation rate was about 10% of the wide open flow. [0220] 5.
Oxygen gas was added to the bottom of the kier so that the gas was
drawn into the internal circulation pump. The gas flow was
regulated to maintain a level of dissolved oxygen in the liquor
without allowing excessive un-dissolved oxygen gas bubbles to form
and discharge from the kier. [0221] 6. NaOH, wetting agent (Scourer
JD), and sequestering agent (SEQ600) was added to the circulation
tank to mix with the water and form a scouring liquor, which was
introduced to the kier through the external circulation pump.
[0222] 7. The temperature was increased at a rate of 3.degree. C.
per minute using non-contact steam. [0223] 8. The kier pressure was
maintained at 2-3 Bar by regulating the oxygen flow and external
circulation flow as the temperature was ramped up and held. [0224]
9. Once the temperature reached 98-100.degree. C. (just below flash
point), the temperature was held for 30-90 minutes. [0225] 10.
Prior to cooling, the oxygen gas was shut off, and the kier
external circulation valve was slowly opened to relieve the oxygen
pressure. [0226] 11. The kier was cooled to 90.degree. C. by
circulating liquor through a non-contact heat exchanger. [0227] 12.
The circulation pumps were stopped, and the kier was drained.
[0228] A 14 kg (OD) sample of the starting flax of Table 8 was
placed in the kier basket and scoured using the low temperature
oxygen scour procedure (3). After scouring and rinsing, the fiber
achieved a 40.94 TAPPI brightness as shown in Table 14.
TABLE-US-00014 TABLE 14 Flax fibers scoured with oxygen scour
procedure (3) CIE TAPPI Whiteness 525 L* a* b* .DELTA.E Index
Brightness 77.02 2.32 12.7 14.48 -16.69 40.94
Example 15
[0229] A 14 kg (OD) sample of the starting flax of Table 8 was
placed in the kier basket and scoured using the low temperature
oxygen scour procedure (3). In addition to the specified chemicals,
0.5% OF magnesium sulfate was added to this scour to act as a
cellulose protectant and to enhance the scour. After scouring and
rinsing the fiber achieved a 38.63 TAPPI brightness as shown in
Table 15 below.
TABLE-US-00015 TABLE 15 Flax fibers scoured with oxygen scour
procedure (3) and magnesium sulfate CIE TAPPI Whiteness 525 L* a*
b* .DELTA.E Index Brightness 75.37 2.38 12.69 12.85 -20.52
38.63
Example 15
[0230] FIG. 11 shows a graph of the NaOH concentration in the
liquor of Examples 12-15. Note the progression of reduced NaOH
consumption going from normal scour (non-oxygen) (Example 12) to
normal+oxygen gas (Example 13) to low temperature+oxygen gas
(Example 14) to low temperature+oxygen gas+magnesium sulfate
(Example 15). Also note the very low NaOH in the first data point
(10 minutes) for Example 15, which was the result of sampling
before the NaOH had a chance to thourghly mix with the liquor in
the kier.
Example 16
[0231] FIG. 12 shows the liquor solids content for Examples 12-15,
which demonstrate surprising results. The liquor solids curve for
the standard scour without oxygen gas (Example 12) shows the same
relationship as the oxygen scour (Example 13). However, Example 14,
the low temperature oxygen scour, showed a significantly lower
liquor solids curve than the higher temperature scours in Examples
12 and 13. However, the scour brightness of 40.94 was significantly
higher than either of the high temperature scours. The low
temperature oxygen scour with magnesium sulfate in Example 15
demonstrated a very low initial level due to sampling, but showed a
solids level higher than Example 14 (but still below the high
temperature scours).
Example 17
[0232] The scoured flax of Examples 12, 13, 14, and 15 were tested
for strength properties. Quite unexpectedly, the oxygen scoured
fibers showed significantly higher strength compared to the
non-oxygen scoured fibers of Example 12. The low temperature fibers
of Examples 14 and 15 had the highest strength of the samples
tested. Table 16 provides the high volume instrument (HVI)
properties below. The HVI is a cotton testing instrument.
TABLE-US-00016 TABLE 16 Strength properties of scoured flax fibers
HVI HVI HVI Strength Length Short Example g/tex mm Fibre % Example
12 39.9 30.6 8.2 Example 13 42.3 31.7 4.7 Example 14 45.2 33.5
<3.5 Example 15 45.2 30.0 8.5
Example 18
[0233] The scoured fibers from Examples 12-15 were laboratory
bleached with hydrogen peroxide using the modified spinner method.
A fixed chemical dose of 4% hydrogen peroxide, 2% sodium hydroxide,
0.1% sodium silicate, and 0.05% DTPA was used for all the samples
at a fiber consistency of 5%. Each set of fiber was bleached at
both 80.degree. C. and 96.degree. C. to ascertain the impact of
bleaching temperature. The data showed a significantly higher
brightness for the oxygen scour Examples 13, 14, and 15 (Table 17).
The data also showed an unexpected increase in brightness for the
low temperature oxygen scour in Examples 14 and 15, compared to the
high temperature oxygen scour of Example 12.
TABLE-US-00017 TABLE 17 Hydrogen peroxide bleached flax fibers
after scouring Peroxide @ 80 C. Peroxide @ 95 C. Example L* a* b*
Brightness L* a* b* Brightness Example 12 84.70 0.09 13.28 52.0
87.00 -0.29 13.75 50.0 Example 13 85.95 -0.22 12.84 54.5 86.48
-0.25 13.98 54.4 Example 14 89.00 -1.06 10.97 62.0 87.38 -1.05
11.72 58.2 Example 15 87.99 -0.95 -0.95 60.2 87.22 -1.05 12.16
57.5
Example 19
[0234] The peroxide bleached samples of Example 18 were then
bleached with a reductive stage to determine the impact of oxygen
and temperature on final fiber brightness. The samples were
bleached with a 0.5% sodium hydrosulfite dose and at a neutral pH
(no pH adjustment). The bleaching was completed using the bag
bleaching method with sample preparation and dosing done in a
nitrogen atmosphere.
[0235] The non-oxygen scour fibers of Example 12 showed only a
slight brightness gain in the reductive stage and had final process
brightness significantly lower than the oxygen scoured samples,
demonstrating the need to activate the fiber to reductive bleaching
by an oxygen treatment (Table 18). The low temperature oxygen
scoured fibers of Examples 14 and 15 showed a significantly higher
brightness than the high temperature oxygen scoured fibers of
Example 13.
TABLE-US-00018 TABLE 18 Peroxide bleached and reductive stage
bleached scoured fibers Peroxide @ 80 C. + Hydrosulfite Process
Peroxide @ 90 C. + Hydrosulfite Process Example L* a* b* Brightness
Y Stage Gain Total Gain L* a* b* Brightness Y Stage Gain Total Gain
Example 12 84.85 -0.28 11.84 52.4 0.4 33.5 84.14 -0.75 11.51 52.8
2.8 33.9 Example 13 87.68 -0.81 11.98 61.6 7.0 42.7 87.20 -0.64
10.41 59.3 4.9 40.4 Example 14 88.41 -0.82 9.98 66.2 4.2 47.3 88.35
-0.38 8.14 64.8 6.6 45.9 Example 15 89.49 -0.92 9.48 65.6 5.4 46.7
88.66 -0.37 8.14 64.4 6.9 45.5
[0236] With respect to the above description then, it is to be
realized that the optimum dimensional relationships for the parts
of the invention, to include variations in size, materials, shape,
form, function, and manner of operation, assembly and use, are
deemed readily apparent and obvious to one skilled in the art, and
all equivalent relationships to those illustrated in the drawings
and described in the specification are intended to be encompassed
by the present invention.
[0237] Therefore, the foregoing is considered as illustrative only
of the principles of the invention. Further, various modifications
may be made of the invention without departing from the scope
thereof and it is desired, therefore, that only such limitations
shall be placed thereon as are imposed by the prior art and which
are set forth in the appended claims.
* * * * *