Note: Descriptions are shown in the official language in which they were submitted.
- TrrLE 1335200
HIGH STRENGTH FIBERS FROM CHlT~ DERlVATIVES
DESCRIPrION
Technical Field
This invention relates to high strength fibers from chitin derivates and
the process for m~hng those fibers.
Background
Chitin (poly-N-acetyl-D-glucosmine) is a polysaccharide widely
distributed in nature and is a major colllponent of the cell wall of various fungi
as well as t_e shell of insects and crust~e~n~. Chitin has been extracted and
purified from its various sollrces and has been formed into potentially useful
articles such as fibers for ml~Ai~l sutures. Chitin-based fibers having both
high tensile strength and high modulus of elasticity p~ d dir~lly without
post fiber t~c~..Pnt would be highly desirable.
Previous work to provide high strength chitin fibers has included the
after-tre~tm~nt of wet-spun chitin fibers in a second coagulation bath as
described in U.S. Patent Nos. 4,431,601 or by drawing the fiber as described
in J~p~nese patent Pub. (Kokai) No. 58-214,513 (K. Inoue et al, published
1983 December 13).
Methods to produce chitos~n (poly-D-gucos~..ine) and chitin acetate
(poly-N-acetyl-O-acetyl-D-glucos~mine) are known and metho~s for spinnin~
~hitos~n and chitin acetate into fibers are described in J~p~nçse Patent Pubs.
(Kokai) No. 5~106901 (T. Yoneyama et al, published 1980 August 25) and
No. 53-126063, (Y. Togura et al, published 1978 November 02) res~;~ively.
In the polys~ch~ride art, optically anisotropic spinning solutions from
cellulose and cellulose acetate have been disclosed. An object in the cellulose
art was to provide a concentrated solution of highly polymerized cellulose
t~i~e~t~- as well as a large degree of acetate substitutions in order to producehigh strength fibers as described in U.S. Patent No. 4,464,323.
1335200
- It has now been discovered that by forming a
fiber from the mixed derivative of chitin or chitosan
acetate/formate that significantly higher tenacity can be
obtained. Higher tenacity chitin acetate fibers are
S obtainable by lowering the degree of substitution. This
is completely unexpected in light of U.S. Patent
No. 4,464,323.
SUMtlARY OF T~E INVENTION
Chitln acetate/formate and chitosan
acetate/formate polymers have now been discovered. Chitin
acetate/formate and chitosan acetate/formate polymers can
be spun into fibers having tenacities at least 4 g/den and
~oduli at ~east 100 g/den. The tenacities can be reached
directly for the as-spun fiber and are preferably at least
5.5 g/den for the chitin acetate/formate fiber and at
least 6 g/den for the chitosan acetate/formate fiber. The
moduli for chitin acetate/formate and for ch~tosan
acetate/formate is preferably 150 g/den. The process for
making chitosan acetate/formate polymer suitable for
preparing fibers having as-spun tenacities greater than
4 g/den comprises the steps of adding formic acid, acetic
anhydride and acetic acid to chitosan.
Chitin acetate fiber having a tenacity of at
least 4 g/den, and a modulus of at least 100 g/den and a
degree of acetylation of less than 2.2 has also been
discovered.
Purified chitin is derivatized to provide chitin
acetate, chitin acetate/formate, and chitosan
acetate/formate. These chitin derivatives can be extruded
from optically anisotropic solutions through an air gap
and i-nto a coagulating bath to form high strength fibers.
Fibers made from the acetate/formate derivatives or low
degree of substitution chitin acetate show increased
strength when compared to non-derivatized chitin fibers or
high degree of substitution chitin acetate.
1335200
- Chitin, when isolated in high molecular weight
form, is soluble at low concentration in only a limited
number of specialized solvent systems. In order to
enhance the solubility of chitin-based polymers, it is
desirable to place organic substituents on the free amine
or hydroxy groups of chitin or chitosan. $hese
substituents perform two functions. First, they provide
organic pendant groups to facilitate dissolution in
organic solvent systems, e.g. trichloroacetic
acid/methylene chloride. Second, the presence of such
substituents disrupts the crystalline, strongly
hydrogen-bonded structure of native chitin, which itself
constitutes a significant barrier to dissolution. Mixed
substituent derivatives such as acetate/formate are
especially attractive in aiding the dissolution and
~pinning processes in that their fiber-forming ability and
viscosity are very well suited for spinning at
concentrations exceeding 10 wt. % and would therefore be
attractive for commercial ~cale manufacture. In addition,
it is observed that the loss of molecular weight as
evidenced by a decrease in solution viscosity with time is
greatly reduced with the mixed substituent derivatives.
Chitin refers to poly-N-acetyl-D-glucosamine
wherein the degree of N-acetyl substitution is from
0.75-1Ø Though chitin is found naturally with the C5-C6
bond in the D-configuration, the chemistry defined herein
would be just as applicable to an L-form and is not
intended to be limited to the D-form.
Chitin derivatives are referred to herein in the
following manner: chitin acetate refers to poly-N-acetyl-
O-acetyl-D-glucosamine wherein the O-acetyl group can be
~ubstituted ~t the C3 and C6 position of the monomer to a
varying degree, with a degree of O-acetylation ranging
from about 0.05 to 2.0; chitin acetate/formate refers to
3~ poly-N-acetyl-O-acetyl-N-formyl-O-formyl-D-glucosamine
wherein the O-acetyl and O-formyl substitution occurs at
1335200
-- the C3 and C6 ring-position of the monomer in a random
di-stribution-within the polymer to a varying degree, with
a degree of acetylation ranging from about 0.05 to 2.0 and
a degree of-formylation ranging from about 0 to 1.95 and
wherein the N-acetyl substitution is a degree of
acetylation ranging from about 0.75 to 1.0 wherein the
N-formyl substitution is a degree of formylation ranging
from about 0 to 0.25 and wherein the total degree of
formylation is greater than 0.05. Chitosan is obtained by
de-N-acetylation of chitin and refers to poly-D-
glucosamine; and chitosan acetate/formate refers topoly-N-formyl-N-acetyl-O-acetyl-O formyl-D-glucosamine
where~n the O-acetyl and O-formyl rubstitutlon occurs at
thè C3 and C6 position of the monomer in a random
distribution within the polymer to a varying degree, with
a degree of acetylation ranging from about 0 to 2.0,
preferably 0.05 to 2.0, and a degree of formylation
ranging from about 0 to 2.0 and wherein the N-acetyl
substitution is a deqree of acetylation ranging from about
0 to 0.75, the N-formyl substitution is a degree of
formylation ranging from ~bout 0 to 1.0 and wherein the
total degree of acetylation is greater than 0.05 and the
total degree of formylation is greater than 0.05. The
total degree of formyl and acetyl group substitution onto
the above-described chitin derivatives is determined by
the types and concentration of reactants and catalysts
used for the preparation of each polymer.
In the preparation of fibers, optically
anisotropic solutions of each chitin derivative were
prepared and then extruded through a spinneret into a
coagulation bath to form fibers which were then wound onto
bobbins.
The anisotropic spinning solutions were prepared
by dissolving the chitin derivative into a ~olvent
comprising trichloroacetic acid/methylene chloride. The
solutions were judged to be anisotropic if-, when
- 1335200
- ~andwiched between a microscope slide and cover slip, they
were birefringent when viewed between crossed polarizers.
Generally, chitin derivatives were found to form optically
anisotropic solutions when dissolved at weight percents
greater than 10% in a 60/40 (w/w) trichloroacetic
acid/methylene chloride solvent.
It is recognized that both the molecular weight
and pattern of ~ubstitution of chitin polymers or chitin
derivative polymers will probably determine their
solubility in any particular solvent and also the
concentrations at which optical anisotropy is observed.
Also, even though a 60/40 (w/w) trichloroacetic
acid/methylene chloride solvent is used for most of the
work described herein, other solvents for chitin or its
derivatives could be used.
The chitin derivative chitosan acetate/formate
can be formed by reacting chitosan in the presence of
acetic acid, formic acid and acetic anhydride. The order
of addition and relative qùantities of these reactants is
important in determining the product obtained.
When chitosan is dissolved first in an aqueous
mixture of acetic and formic acids followed by the
addition of acetic anhydride, predominantly N-formylation
and O-formylation occur, accompanied by ~ome O-acetyl
substitution. Rather, if the chitosan is first dissolved
in an aqueous solution of acetic acid and acetic anhydride
followed by the addition of formic acid, a mixture of
N-acetylation, O-acetylation, N-formylation and
O-formylation is obta-ined.
The ratio of acetic acid to formic acid in the
above solutions will determine the relative degree of
substitution obtained. In addition, the predominant N-
substituted species is determined by which corresponding
acid (acetic or formic) i~ added first to the chitosan in
the presence of acetic anhydride; the level of acetic
anhydride being rate limiting.
-6-
1335200
The chitin derivative, chitin acetate/formate,
is formed by reacting formic acid and acetic anhydride
with chitin in the presence of an acid catalyst.
Acetylation of chitin by acetic anhydride in the presence
of an acid catalyst occurs rapidly. Therefore, to control
the level of formylation occurring on the chitin, the
formic acid can be added first to the chitin in the
presence of an acid catalyst and allowing sufficient time
for formylation to occur before the subsequent addition of
acetic anhydride. An acid catalyst useful in these
reactions is perchloric acid.
The coagulation bath used during fiber
formation consisted of cold methanol, which is a
non-solvent for chitin and its derivatives. The
coagulation bath was between 20 and 30 inches in length.
Any suitable non-solvent for chitin or its derivatives
could be used ~n place of methanol for the purpose of
coagulating the fiber spinning solution.
There are many parameters which can be
varied in the spinning scheme and one could readily adjust
tpinneret orifice diameters, length of the air gap
~pacing, jet velocity, bath conditions, ratio of windup
speeds to jet velocity, as well as other parameters in
order to optimize various physical properties of the
fiber of this invention. -
The chitin derivative polymers produced
according to the present invention are spun fromanisotropic solution and form high strength fibers.
Fibers prepared from chitosan acetate/formate have tensile
properties which typically fall between 4-8 g/d tenacity
and 150-250 g/d initial modulus. It ~s expected that
articles other than fibers, ~uch as cast or molded
products, could be produced from the polymers described
herein and may also demonstrate high strength properties.
BRIEF DESCRIPTION OF THE DR~WING
Fig. 1 is a schematic diagram of an apparatus
for air-gap spinning of anisotropic solutions of chitin
and chitin derivatives.
--6--
1335200
Fiq. 2 is a schematic diagram of a twin cell
apparatus for air-gap spinning of anisotropic solutions of
chitin and chitosan derivatives.
Fig. 3 is a schematic diagram of a mixing plate
used in conjunetion with the apparatus of Fig. 2.
DETAILED DESCRIPTION OF THE DRAWING
In using the apparatus of Fig. 1 an ~nisotropic
solution of chitin or a chitin derivative was placed in
spin cell (G). A piston (D) activated by hydraulic press
(F) and associated with piston travel indicator (E) was
positioned over the surface of the solution, excess air
expelled from the top of the cell and the cell sealed.
The spin cell was fitted at the bottom with the following
screens (A) for solution filtration: four to six 325-mesh
screens. The filtered ~olution was then passed into a
spinneret pack (s) containing two or three 325-mesh
screens. Solutions were-extruded through an air gap at a
controlled rate into a static bath (C) using a metering
pump to supply pressure at piston (D). The fiber was
passed around a pin (H), pulled through the bath, passed
under a second pin (I) and wound onto a bobbin. The air
........ ~
gap between the spinneret face and the coagulation bath
was typically 0.6 to 2.0 cm. The coagulation bath
temperature was generally held below 100C with specific
values as given in the examples.
In using the apparatus of Fig. 2, filter plate
(J) is replaced by mixing plate (R). Polymer dope is
placed in cylinder bore (T) and then piston (D) and cap
plate (L) is fitted to the spin cell (G). A driver fluid
(e.g. water) is pumped into the upper part of bore (T)
through feed line (F). The piston (D) is displaced by the
driver fluid, thereby pushing the polymer dope through
passages (W), (S) in mixing plate (R) and then through
passage (X) in distribution plate (M) into ~econd cylinder
bore (U). This process is then reversed by pumping fluid
through feed line (X). The aforementioned forward and
133S200
- reverse process is repeated several times to effect a
mixing of th,e polymer dope. Component tE) acts to sense
the position of cylinder (D).
After mixing is complete (about 30 cycles),
mixing plate (R) is replaced by filter plate (J) and
polymer dope is extruded from bore (T)'through passage
(W), through filter pack (A) containing 2 Dutch Twill
Weave 165 x 800 mesh screens, through passage (Y) in
filter plate (J) and passage (Z) in spinneret mounting
plate (O) and out of spin cell (G) through spinneret (~).
The extruded dope is ~pun into a bath and taken up as
described for Fig. 1. Pressure of the polymer dope during
~pinning i5 measured by pressure transducer (P).
TEST METHODS
Inherent viscosity (I.V.) is calculated using
the formula:
Inherent viscosity ~inh ~ (ln ~ )/C where C is
; the polymer concentration in grams of polymer per
deciliter of solvent. The relative viscosity (~r-l ) iS
determined by measuring the flow time in seconds using a
standard viscometer of a solution of 0.5 g (except where
indicated) of the polymer in lO0 ml hexafluoroisopropanol
at 30C and dividing by the flow time in seconds for the
pure solvent. The units of inherent viscosity are dl/g.
Jet Velocity (J.V.) is the average exit
velocity of the spinning bolution from the spinneret
capillary as calculated from the volume of solution
passing through an orifice per unit time and from the
cross-sectional area of the orifice and is reported as
meters per minute.
Filament tensile properties were measured using
a recording stress-strain analyzer at 70F (21.1C) and
65% relative humidity. Gauge length was 1.0 in (2.54 cm),
and rate of elongation was 10%/min. Result~ are reported
a~ T/E/M. Tenacity T is break tenacity in g/den,
Elongation (E) is elongation-at-break expressed as the
- 9 -
1335200
~ percentage by which initial leng~h increased, and Modulus
(M) is initial.tensile modulus in g/den. Average tensile
properties for at least three filament samples are
reported. The test is further described in ASTM D2101-79
- 5 part 33, 1981.
Degree of Substitution ~DS) of acetate or
formate is determined by proton-NMR in the following
manne r:
The spectra are determined in deuterated
trifluoracetic acid solvent and using tetramethylsilane
(TMS) as a ~tandard. The D.S. is determined by
integrating the area due to the protons on carbons Cl
through C6 of the glucosamine derivative (6.0 to 3.0 ppm)
and comparing it with the total area due to the methyl
group protons (2.5 to 2.0 ppm) using the following
formula:
D.S. ~ (M/(G/7))/3
where: M - area of methyl group protons
G ~ area of the protons on carbons C
through Cc of the glucosamine
derivative
The formyl protons are observed at about 8.4 ppm for the
amide and at about 8.2 ppm for the ester. The D.S. of
formyl groups is determined in a similar fashion using the
following formula:
D.S. - F/(G/7)
where: F - area of formyl protons
G - area of the protons on carbons C
through C6 of the glucosamine
derivative
To determine the relative.amounts of acetyl and formyl
content in the mixed derivatives both formulas are used.
EXAMPLES
RUN A .
Chitin was icolated from shrimp hells and spun
into fiber according to the following procedures:
--10--
133S200
Isolation of Chitin
Shrimp shells obtained from Gulf Cities
Fisheries of Pascagoula, Miss. were placed in large
containers and eoaked in acetone for 5 to 7 days, after
5 which the acetone was filtered off and the shells rinsed
: with additional acetone to remove as much pigment as
possible. The shells were then air dried for 72 hours.
r The dried shells were ground into a flake using an Abbe
cutter. The ground shells (500 g) were decalcified by
treatment with ice cold 10% hydrochloric acid (4 to 6 l)
with etirring for 20 minutes. The liquid was then removed
by filtering and the shells rinsed with water. This acid
treatment was repeated and the decalcified shells were
rinsed with water until neutral and allowed to air dry.
The dry solid was suspended in 2.5 l of 3% sodium
hydroxide in a 5 l flask and heated at 100C for 2 hours.
~he suspension was then filtered and the remaining solid
washed with water. This caustic treatment was repeated
- and the chitin obtained was washed with water until
neutral. The chitin was then washed successively with
methanol and acetone, air dried and lastly dried in a
vacuum oven for about 12 hours at 120C.
Spinning
Chitin obtained by the above procedure was
ditsolved at 24C in a 60/40 (w/w) trichloroacetic
acid/methylene chloride mixture, to form a solution
containing 13.5% rolids. The eolution was tested and
found to be anisotropic.
The chitin solution above was extruded into
fibers using the apparatus represented by Fig. l and
described previously. The solution was extruded through
0.004" diameter holes of a 10-hole spinneret at a jet
velocity of 15.2 M/min., passed through a 1.25 cm air gap,
into a 0C methanol bath and wound onto bobbins at a rate
of 15.5 M/min.
Fiber properties were measured-as described
above and are reported in Table I.
--1 0--
RUN B 1335200
Chitin acetate with a high degree of
substitution of acetyl groups was synthesized and spun
into fiber by the following method:
Preparation of Chitin Acetate
200 ml of reagent grade methylene chloride,
900 ml of reagent grade acetic anhydride, and 125 ml of
glacial acetic acid were added to a 1 l resin kettle
equipped with a ~tirrer and nitrogen inlet. The mixture
was cooled to about 0C in a methanol bath and 20 g of
chitin, prepared as in Run A, were added. 6 ml of 70%
perchloric acid were then added slowly and the mixture was
stirred about 12 hours. After stirring, the mixture was
filtered on a fritted Buchner funnel and excess acetic
anhydride was removed by aspiration. The solid was washed
thoroughly with methanol, a~etone, 10% sodium bicarbonate,
water, and lastly acetone, after which the solvent was
removed by aspiration. The remaining solid was then air
dried for about 12 hours to give 25 g of chitin acetate as
a white solid. The inherent viscosity of the polymer was
5.72 dl/g and the degree of substitution was 2.95.
Spinning
Chitin acetate prepared by the above procedure
was spun as in Run A using the apparatus represented by
Fig. 2 with the different spinnning parameters listed in
Table 2.
Fiber properties were measured as described
above and reported in Table I.
EXAMPLE 1
Chitin acetate with a relatively low degree of
~ubstitution of acetyl groups on chitin was synthesized
and ~pun into fiber by the following method:
Preparation of Chitin Acetate
200 ml of reagent grade methylene chloride,
400 ml of reaqent grade acetic anhydride, and 125 ml of
glacial acetic acid were added to a 1 l resin kettle
- 1335200
_ equipped with a stirrer and nitrogen inlet. The mixture
was cooled to about 0C in a methanol bath and 20 g of-
chitin, prepared as in Example 1, were added. 3 ml of 70%
perchloric acid were then added slowly and the mixture was
stirred about 12 hours. After stirring, the mixture was
- filtered on a fritted Buchner funnel and excess acetic
anhydride was removed by aspiration. The solid was washed
thoroughly with methanol, acetone, 10% sodium bicarbonate,
water, and lastly acetone, after which all of the solvent
was removed by aspiration for about 12 hours to give 25 g
of chitin acetate as a white ~olid. The inherent
viscosity of the polymer was 8.76 and the degree of
substitution was 2.0
,. ~ . ~ ~
Spinning
Chitin acetate prepared by the above procedure
was spun as in Run A using the apparatus represented by
Fig. 2 with the different spinnning parameters listed in
Table 2.
Fiber properties were measured as described
above and reported in Table I.
EXAMPLE 2
Isclation of Chitin
Wet shrimp shell waste (25 kg) was sorted
manually to remove extraneous substances and boiled in
water for 2 hours. The shells were collected by vacuum
filtration and placed into cheesecloth pouches. Using
one-half of the batch at a time, the shells were then
boiled in 2% NaOH (50 1~ under a nitro~en atmosphere for
1 hour, collected, pressed out and washed once with water.
The shells were then boiled for 9 hours in 2% NaOH ~50 1)
under nitrogen for a second time, collected, pressed out,
washed in water and immersed in 50 1 10% acetic acid for
1 hour at room temperature. The shells were collected by
filtration, washed twice more in water and pressed out.
They were finally suspended in acetone (4 1), collected by
-12-
-13-
1335200
- filtration, washed once more with clean acetone and
allowed to air dry. The.yield was 1.2 kg dry chitin.
Preparation of Chitin Acetate
Chitin (50 g) prepared as described above was -
_ 5 ground in two steps to pass through a 0.5 mm screen. The
~ ground chitin was placed in a Soxhlet extractor and
extracted with acetone until the extract was clear. After
air drying, the chitin powder was washed twice with
methanol, pressed out and heated to 77C in 15% methanolic
potassium hydroxide for l hour under nitrogen. The powder
was collected by filtration, pressed out, washed once with
water followed by two washes in glacial acetic acid.
After the final wash, the powder was pressed out and
suspended using methods described above in cooled acetic
anhydride (500 ml) and methylene chloride (500 ml)
containing perchloric acid (2 ml) all at -22C. After
16 hours, the temperature was raised to 13C and the
r reactants allowed to stir for an additional 24 hours
reaching a final temperature of 18C. The polymer was
collected by filtration, pressed out and washed twice with
methyl alcohol. The product was then washed once in 5%
sodium bicarbonate, followed by two-washes in water and a
final wash in acetone. The product was dried in a vacuum
at 55C. The yield was 57 9. D.S. - 1.4 based on NMR
analysis.
Spinning
Chitin acetate prepared as described above was
spun using the method of Run A and the equipment described
by Figure 1. The spinning solvent was 60/40 w/w
trichloroacetic acid/methylene chloride. Pertinent
~pinning parameters appear in Table II.
Fiber properties were measured as described
above and appear in Table 1.
EXAMP~E 3
Chitin acetate/formate was prepared from chitin
and then spun into fiber by the following method:
-14-
- 1335200
Preparation of Chitin Acetate/Formate
200 ml of reagent grade methylene chloride and
255 ml of formic acid (95-98%) were added to a 1 l resin
kettle equipped with a stirrer and nitrogen inlet and
cooled in a refrigerated bath to 0C. 280 ml of acetic
anhydride were added to the bath, allowed to cool to 0C,
and then 20 g of chitin prepared as in Run A were added,
folIowed by the slow addition of 6 ml of 70% perchloric
acid. The mixture was stirred for about I2 hours at 0C.
The cUspension was washed thoroughly with methanol,
acetone, 10% sodium bicarbonate, water, and lastly
acetone. After removing the solvent by aspiration, the
solid was aid dried for about 12 hours and yielded 24 g of
chitin acetate/formate as a white solid.
The inherent viscosity of the polymer was
11.4 dl/g and the degree of substitution was 2.5/0.5
(acetyl/formyl).
Spinning
Chitin acetate/formate prepared by the above
procedure was spun the same as in Run A using the
apparatus represented by Fig. 2 with the different
spinnning parameters listed in Table II.
Fiber properties were measured as described
above and reported in Table I.
EXAMPLE 4
Chitosan acetate/formate was prepared from
chitosan which itself was prepared from chitin and then
the chitosan acetate/formate was spun into fi~ers, per the
following procedures:-
Preparation of Chitosan
Shrimp shells were washed in acetone and ground
into a fla~e as described in Run A. The washed and cut
shells (310 g) were then treated with ice cold 9%
hydrochloric acid (2 l water, 1 l ice chips, 1 l 37% HCl)
in a large container for 20 ~inutes. The ~olution was
filtered and the remaining solid rinsed with water. This
-14-
-15-
- 1335200
acid treatment was repeated, after which the solid was
washed with water until neutral and then washed with
acetone and finally air dried. The resulting solid was
treated with 2 1 of 50% ~odium hydroxide at 100C for
2 hours. The suspension was filtered and the remaining
solid was rinsed with water. This caustic treatment was
: repeated a second time and the solid was collected by
filtration, washed until neutral with water, and then
washed with methanol and acetone and allowed to air dry.
This procedure yielded 86 g of chitosan as a white solid.
The inherent viscosity of the chitosan was
11.3 dl/g in 50% aqueous acetic acid.
Preparation of Chitosan Acetate/Formate
750 ml of 95-98~ formic acid and qO g of
chitosan prepared above were added in a 4 1 resin kettle.
The mixture was stirred under nitrogen in a refrigerated
bath at 0C for 1.5 hours until all the polymer was
dissolved.
250 ml of qlacial acetic acid were then added
and the mixture stirred until a homogeneous solution was
obtained. The mixture was stirred an additional 30 min.,
500 ml of reagent grade acetic anhydride were added and
then the mixture was stirred for about 12 hours at 0C.
The resulting gel was broken up and soaked in methanol
(6 liters) for a few hours to precipitate the polymer.
The polymer was filtered and the 601id gel chopped in a
blender. The precipitated polymer was washed thoroughly
with methanol several times, and then with acetone. ~he
solid was aspirated to remove excess solvent and then
allowed to air dry overnight. The yield was 53 g of
chitosan acetate/formate as a white solid.
The inherent viscosity of the polymer was
10.8 dl/g and the degree of 6ubstitution was 0.4/2.3
(acetyl/formyl).
Spinning
Chitosan acetate/formate prepared by the above
procedure was spun as in Run A usinq the apparatus -
-16-
1335200
represented by Fig. 2 with the different spinnning
parameters listed in Table II.
Fiber properties were measured as described
above and reported in Table I.
EXAMPLE 5
~ -Chitosan acetate/formate was prepared according
. to the general procedure in Example 4 with the changes
noted below.
750 g of 95-98% formic acid and 40 g of chitosan
were mixed in a 4 1 resin kettle at 0C. Once the
chitosan was well dispersed 500 ml of acetic anhydride
were added and the reaction allowed to stir for 95 hours
at 0C. At that time the polymer was essentially
completely in solution and was isolated by precipitation
into cold methyl alcohol ~6 liters at 0C). The white
product was collected by vacuum filtration, then washed
twice with water, followed by another wash in methyl
alcohol and a final wash in acetone. The product was
allowed to air dry yielding a white fibrous solid.
Spinning
; Chitosan acetate/formate prepared by the above
procedure was spun using the method of Example 1 and the
equipment described by Figure 1. ~he spinning solvent was
49:51 w/w trichloroacetic acid/methylene chloride. Other
pertinent spinning parameters appear in Table II.
Fiber properties were measured as described
above and appear in Table I.
......
-17- 1335200
IABLE I
. . .
FIBER ~OP~K11 S
D.S .
ACEIATE/ TENSILE r~P~llES
EX. DESCRIPTION FORMATE DPF TEN./ELONG./MOD.
A Chitin l.OjO.O 15.7 1.3gpd/2.6%/107gpd
B Chitin 2.9/0.0 7.0 2.5gpd~7.3%/9Ogpd
Acetate
1 Chitin 2.0/0.0 4.5 4.3gpd/4.5%/169gpd
Acetate
2 Chitin 1.4 5.4 5.9gpd/6.4%/206gpd
Acetate
3 Chitin 2.0/0.3 5.1 5.9gpd/6.8%/162gpd
Acetate/Formate
4 Chitosan 0.4/1.4 19.1 7.09pd/6.8%/194gpd
Acetate/Fonmate
Chitosan O.3/1.5 21.4 6.2gpcl/5.8%/185gpd
Acetate/Fonmate
D.S. - degree of substitution, these fiber values can differ from thc
of the starting polymer because some partial deesterification
may occur during conversion to fibers
DPF - denier per filament
EX. - Example or run designation
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I 335200
T~BLE II
SPINNING pARAnET~Fs
Parameters Run A Run B Ex. 1 Ex. 2 Ex. 3 4 EX. S
% Solids . 13.5% 15% 15% 15% 15% 17% 15%
Spinneret
No. of Holes 10 1 1 5 1 1 20
Dia. of ~oles 0. 0102 0.0076 0.0076 0.0076 0.0076 0.0127 0.0076
( C~l~ )
Jet Velocity 15.2 29.9 16.6 1.5 20.0 12.0 3.4
(My~in)
Air Gap (cm) 1.25 1.4 1.1 1.3 1.4 1.0 1.9
Coagulation Bath 0 1 8 16 -20 5 -11
Temp. (C)
Wind-up P~te 15.5 24 40 21.3 17 9.9 6.8
(M4~in)
This application is a division of Canadian Divisional Application No. 616225
filed November 06, 1991.
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