CA1326663C - High strength fibers from chitin derivatives - Google Patents

Abstract

ABSTRACT

High tenacity chitin acetate/formate and chitosan acetate/formate fibers and the process for making such fibers are disclosed.

Description

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TITI E
HXGH S~ENGTH PIBERS PROM CHITIN DERI~ATlY~
DESCRIPTION
Technical ield This inven~ion relates ~ high streng~ fibers ~om ehitin deriva~es and the process ~or mal~ng ~ose ISbers.

Chitin ~poly-N-acetyl-D-glucosmine~ is a polysaccha~ide widely dist~ibllted in na~ure and is a major component of the cell wall of various ~ungi as well as the shell of ;nseets and crus~aceans. Chitin has been extracted and purified ~om its va~ious sour~es and has been formed into potentially useful .article~ such as fibers ~or medical sutures. Chi~n-bas~d fibers ha~ing bo~
high tens.ile streng~ and high modulus of elas~ci~y prepared di~ectly without post fib~r treatment would be highly desirable.
Previous work to provide high strength chitin fibers has included the afte~-treatment of wet-spun çhitin fibers in a second coagulation bath as described in U.S. Pa~ent Nos. 4,431,601 or by drawillg ~e fiber as described in Japanese patent Pubo (Kokai) No. 5~-214,513 (K. Inoue et al, published 1983 D~ember 13).
Methods to produce chitosan (poly-D-gucosamine) and chitin ace~ate (poly-N-acet~ O-acetyl D-glucosamine) are Icnown and methods for spinning , chi~san ~d chi~n scetate into fibers are described in Japanese Patent Pubs.
(Kokai) No. 5~106901 ~. Yoney~ma t al, published 1980 August 25) and No. 53-126063, (Y. ToguIa e~ al, published 1978 November 02) respectively. : -.
,In the polys~ccharide art, optically anisotropic spinning solutions from c~llulose and cellulose acetate have been disclosed. An object in ~e cellulose art was ~o provide a concen~a~ed solution of highly polymerized cellulose triacetate as well as a large degr~ of acetate substitutions in order to producegh streng~ fibers as described in U.S. Patent No. 4,464,323. ~ ~ .

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It has now been discovered that by forming a fiber from the mixed derivative ~f chi~in or shitosan : :
acetate/formate that ~ignificantly higher tenacity can be obtained. Higher tenacity ehitin acetate f~ber~ are ~btainable by low~ring the degree of sub~titutlon. This is completely unexpected in light of U.S. Patent No~ 4,464,323~
SUMMARY OF THE INYENTION
Chitin acetate/formate ~nd chitosan acetate/~ormate polymers have now been disrovered. Chitin ~ce~ate/formate and chitosan acetate/formate polymers can be ~pun into fibers having tenacities at least 4 ~/den and moduli ~t least 100 g/den. The te~acities can be reaehed directly for the as- pun ~ber ~nd are prefer~bly ~t least 5.5 g/den ~or the chitin acetate/formate ~iber and at le~st 6 g/den for the chitosan acetate/formate ~iber. The ~oduli for chitin ~cet~te/ormate ~nd for ch~to~an ~cetate/f~rmate i~ preferably 150 g/den. The proc2ss f~r making chitosan acetate/formate polymer ~uitable for preparinq ~iber having as-spun tenacities greater than 4 g/den comprises the steps of adding formic acidt acetic ~nhydride ~nd ~cetic acid ~o chitosan.
Chitin aZeetat~ iber having a tenacity of at least 4 ~/den~ aZnd ~ ~odulus of ~t least lO0 ~/den and a ~5 degree o ~Zcetylati~n of le~s than 2.2 has ~l~o been d~covered.
~ Zurified chitin is deriYatized t~ prcvide chitin acetage, chitin ~Z-et~te/formate, and chitosan acetat~/formate. These chitin deriv~tives can be ~xtruded 3~ from ~ptaeally ani ~t~pi~ Zs~lutions throu~h an ~ir gap and into a eoagul~Zting bath to for~ high streng~h fibers.
Fibers ~ade from the ~eetate~formate derivatives or low degree o~ substitution chitin acet~te.show increased ~ :
stre~gth ~hen compared to no~-deriv~ized chitin fibers or ~ .
high degree of su~itution chi~in Zacet~te~

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, -3-Chitin, when i~olated in high molecular weight form, is soluble ~t low concentration in only a limited number of specialized ~olvent cystems. In order to e~hance the solubility of chitin-based polymers, it is desir~ble to place organic substi~uents on the ~r~e ~mine or hydroxy groups of chitin or chitosan~ ~hese substituents perform two functions. First~ they pro~ide organic pendant groups to facilit~te dissolution ;n organic olvent systems, e.9. trichloroacetic acid/methylene chloride. Second, the presence of ~uch substituents disrupts the crystalline, strongly hydrogen-bonded ~tructure of native chitin, which itself constitute~ a ~ignificant barrier tc di~solution. Mixed ~ubst$tuent d~rivatives uch as ac~ate/for~ate are 1~ especially ~ttractive an ~iding the dis~olution ~nd spinning processe~ in that their fib~r-formin~ ability and ~iscosity ~re very well ~uited ~or ~pinning at concentra~ions exceeding 10 wt. % and would therefore be attractive for commercial ~cale ~anufacture. In addition, it is o~ser~ed that the loss of molecular weight as evidenced ~y ~ decrease in sol~tion viscosity with time is qreatly reduced with the mixed substituent derivatives.
Chitin referc to poly-N-acetyl-D-glucosamine wherein the degree of N-acetyl 5ubstitution is from 0.75-1Ø Though chitin i~ found naturally with the C5-C6 bond in the D-configuration, the chemistry de~ined herein ::-would be just ~s applica~le to ~n L-form and is not - ::
intended to ~e limited to the D-form.
Chitin derivativ~ are referred to herein in the ~ollowing m~nner: ehitin ~cetate refer to poly-~-~cetyl-0-~etyl-D-glucosamine wherein the 0-~cetyl group can be ~ubstituted at the C3 and es positio~ of the monomer ~o ~ :
varying degree, with a degree of 0-acetylation ranging -~
from about 0.05 to 2.0; ch;tin acetate/~ormate refers to ~:
poly~-N-~cetyl-0-~cetyl-N-formyl-0-ormyl-D-glu~o amine wherein the 0-~ce yl and 0-formyl ~ubstitution occurs at "
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the C3 and C6 ring-position of the monomer in a random distribution within the polymer to a varying degree~ with a degree of acetylation ranging from about 0005 to 2.0 and a degree of formylation r~nging from about 0 to 1.95 and wherein the N-acetyl ~ubstitution is a degree ~f ~, acetylation ranging from about 0.75 to laO wherein the N-formyl ~ubstitution is a degree of formylation ranging from abDut 0 to 0.25 and wherein the total degree of f~rmylation i~ greater than 0.05. ~hi~osan is obtained by de-N-~cetylation of ohitin and refers to poly D-glucosamine; ~nd zhitosan ~cetate/formate refers topoly-~-formyl-N-hcçtyl-0-acetyl-0 formyl~-yluco6amine wher~ln the 0-acetyl ~nd 0-ormyl sub~titution occurs ~t the C3 and C6 position of the monomer ~n a random ~5 distribution within the polymer to ~ varying degree, with : a degree of acetylat;on ran~ing from about 0 to 2.0, preferably 0.05 to 2.0, and a degree of formylation ranging from about 0 to 2.0 ~nd wherein the N-acetyl ubstitution i~ a degree of acetylation ranging from about 0 to 0.75, the N-formyl 6ubstitutisn is a degree of formylation r~nging from abou~ 0 to loO ~nd wherein the total degree of acetylation is greater than 0.05 and the total degree of formylation is greater than O.OS. ~he tot~l degree o formyl and ~cetyl group substitution onto :
the above-described chitin d~rivatives is determined by the types and concentration of r~actants and catalysts us~d foz the preparation of eaçh polymer. ~ .
In th~ preparation of fiber~, opti~ally -.~
~nicotropic 601utio~s of each chitin derivative were ~:.
30 prepared and then extruded through a spin~eret into a :~
coagul~tion bath to form fibers which were then wound onto bobbins .
The ~ni~otropic 6pinning solutions were prepared by dissolving ~he chitin derivative in~o ~olvent . 35 comprising trichloroacetic acid/methylene chloride. The ~olutions were ~udged to be ~nisotropic if, when :

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and~iched between a microscope lide and ~over ~lip, they were birefr;~gent when viewed between crossed polari~er~.
Generally, chitin derivative~ were found to orm optically ani~otropic ~olutaons when dissolved at weight perceAts greater than 10% in a 60/40 ~w/w) ~richloroacetic acid/methylene chloride ~01Yent.
It is recognized that bsth the ~olecular wei9ht and pattern of ~ubst;tution of chitin polymers or chitin derivative polymers will probably determine their ~olubility in any particular ~olvent and also the concentrations at which optical anisotropy i~ oh~ervéd.
Al50, even though a 60f40 (w/w) ~richloroacetic acid/methylene chloride ~olvsn~ is used or ~ost of the work described herein, other olvents for chitin or its deriv~tives could be used.
The chitin derivative chitosan acetate/formate can be formed by reacting chitosan in the presence of ~cetic ~cid, formic ~cid ~nd acetic anhydride. The order ~ of ~ddition ~nd relative quantitie~ o these rsactant5 is ::~
; 20 important in determining the product obtained.
,~ When chitosan is dissolved first in an aqueous mixture of acetic and formic acids followed by the ~dditio~ of acetic anhydride, predominantly N-formyla~ion and O-formylation oceur, acc~mpanied by some O-acetyl ~5 ~ubstitution. Rather, if the ~:hi~osan is first dissolved in an ~queous 601ution of acetiic acid and acetic ~nhydrid2 ~ :
ollowed by the ~ddition of ~ormic acid, a mixture o~ .
N-acetylation, O-acetylation, N-formylati~n and O-formylation i~ obtained.
The ratio of acetic acid to formic acid in the ::
above ~olution~ will deter~ine the relative degree of ~ ~
~ubstitution obt~inedO In addition, the predominant N- -- .
substituted ~pecies is deter~ined by which corresponding ~id (acetic ~r for~ic~ is added first to the chito~an in 3~ the presenGe of ~ceti~ ~nhydride; the level of ~cetic :
anhydride being rate limiting.

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~ he chitin derivative, chitin acetate/f~rrnate, is formed by reacting formic ~cid and acetic anhydride with chitin in the presence of an acid catalyst.
Acetylation of chitin by acetic anhydride in the presence 5 of an acid catalyst occur~ rapidly. Therefore, to control - the level of formylation occurring on ~he chitin, the formie acid can be ~dded first to the chitin in the pre ence of an ~cid eatalyst and ~llowing sufficient ~ime for ~ormylation to occur before the ~ubsequent ~ddition of acetic anhydride. An ~cid catalyst u~eful in these re~tions i5 perchloric acid.
The coagul~tion bath used during fiber formation consisted of cold ~ethanol, whieh i~ a non-~olvent for ~hitin and its deri~ati~es. The coagulation bath was between 2~ and 30 inche~ in l~ngth.
Any suitable non ~olvent for chitin or it~ derivatives ~-eould be used in place of methanol for the purpose of ! coagulating the fiber ~pinning solution.
There are ~any parameters which can be 2~ varied in the spinning scheme ~nd one could readily adjust ~pinneret orifice diameters, leDngth of the air gap spacing, jet velocity, bath conditions, ratio of windup ~peeds to jet vel~city, ~s wel:l as other parameters in ::
order to optimize var~ous physic31 prop~rties o the fibers of thi~ invention.
The chitin derivative polymers produ~ed ~ccording ~o the p~esent inYen~ion are ~pun from ~-ani~otropic ~olution ~nd form high strength fibers.
Fiber~ prepared from chito~an acetate/form~te have tensile properties whioh typically fall between 4-8 g/d tenacity and 150-250 g/d initial modulus. It is expected that arti~l~s other than ~ibers, ~uch as cast or ~olded products, coulB be produced ~rom the polymers described ~ .
: herein and ~ay Dl~o demonstrate high ~trsngth prDperties. - .
~RIEF DESCRIPTION OF THE DRAWIN5 ~ig~ l is ~ ~chemati~ diagram ~f an apparatus ; f9r ~ir-gap spinning of ani~otropic ~olutions of chitin and chitin derivatives.
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Fig. 2 is a schematic diagram of a twin cell appara~us for ~ir-gap spinning of anisotropic ~olutions of chitin and chitosan derivatives.
Fig. 3 is a ~chematic diagram of a mixing plate used in conjunction with the appaxatus of ~ig. 2.
DETAILED DESCRIPTION OF ~EIE DRAWIMG
~n using the appa~atus of Fig. 1 ~n ~ni~o~rQpic ~olution of chîtin or a chitin derivative was placed in ~pin cell ~G). A pi~ton (D) actiYated by hydraulic press (F) and ass~ciated wi~h p1ston travel indicator (E) wa. :-~
po~itioned over ~he surface of ~he ~olution, excess ~ir expelled ftom the top of the cell and th2 eell ~ealed.
The spin cell w~s fi~d ~t the ~ottom with he following -:~
~creens ~A) ~or colution fil~ration: four o six 325-mesh screens. The filtered ~olution was then passed Anto a spinnere~ pack (B) containing two or three 325-~esh ficreens. Solutions were extruded through ~n 3ir gap ~t a controlled rate in~o a ~tatic ba~h (C) using a ~etering pump to ~upply pressure at piston (~ h~ iber was pas~ed around a pin (H), pulled through the bath, passed under a ~econd pin (I) ~nd wound onto a bobbin. ~he air gap between the spinneret face ~nd the coagulation bath ~-~
was typically 0.6 to 2.0 cm. The coagulation bath temperature was gener~lly held below 100C with specific value~ ~s giv~n in the ~xampl es . -In using the apparatus of Fiy. 2, filter plate ~J) i6 repli~ced by mixing plate ~R). Polymer dope is ~
plaeed in ~yli~der bore tT~ and then piston (D) and c~p ~. .
plate ~L) i~ itted to the spin cell (G~. A driver fluid (e~g. wat~r) ~ pumped ~nto the upper part of bore (T) through feed line ~). The piston (D~ i~ displaced by the :~
driver fluid, thereby pushing the polymer dope thr~ugh p~ssages ~ S) in ~ixing plate (~) and then ~hrsugh pass~ge ~K) in di tribution pl~te (M) in~o ~econd ~ylinder 35 bor~ ~U). Thi6 proce~s is then reversed by pu~ping fluid ~:
through feed line ~X~. ~he aforement;oned forward and :''' ' .'~

~', ~ 3 ~ 3 rever~e process is repeated several times to effect a mixing of the polymer dope. Component ~) acts to sense the position of cylinder (D).
After mixing i~ complete (about 30 cycles), 5 mixing plate (R) is repl~ced by ilter plate (J) and polymer dope is extruded from bore ~T) through passage (W), through filter pack (A) containing 2 Dutch ~will Weave 165 x BOO mesh screens, through passage (Y~ in ilter plate (J) and pas~2ge (2~ in spinneret ~ounting plate ~0) and out of spin cell (G) through ~pinneret tB).
The extruded dope is 5pun anto a hath and taken up ~6 described for Fig. 1~ Pressure of ~he polymer dope during ~pinning i~ ~easured by pressure tr~nsducçr (P).
TEST METHODS -:~
Inherent viscosity (I.V.j is calculated using the formula:
Inherent vi~cosity ninh ' (ln ~r-l )/C where C is the poly~er concentration in grams of polymer per i deciliter of ~olvent. ~he relative vi~cosity ~ ) is determined by measuring the flow time in seconds using ~
~tandard viscometer of a solution o~ 0.5 g (except where indicated) of the polymer in 100 ml hexaflu~roisopropanol . at 30C and dividing by the flow time in seconds ~or the pure ~olve~t. The units uf inherent visc~sity are dl/g. :~
Jet Velocity (J.V.~ i~ the ~verage exit v~locity of the sp~nning solution from the ~pinneret c~pillary a~ ~alculated from the volume of ~olution pa~sing through an orifice per unit time and from the ~ ~ro~s-~e~tional area o~ the orifi~e ~nd is reported DS
'j 3~ ~eter~ per ~inute.
Filamer~t tensile properties were measured using recording ~tres~-&tr~in analyzer at 70DF ~21.1~C) and 65% relative humidi~y. ~uge length was 1.0 in (2.5~ cm), ~-~nd r~te of elong~ti~n was 10%/min. Results ~re r~ported 35 ~ T/~/M. Tena~ity T is break tenacity in g/deni, - -El~ngati~n ~E) i~ elongation-at-break expres~ed as the .

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-percentage by which initial length increased, and Modulus ~:
(M) is initial tensile modulus in g/den. Average tensile ~:~
properties for at least three filament ~amples are ::
reported. The te~t is further described in ASTM D2101~79 part 33, 1981.
Degree of Substitution (Ds) of acet~te or formate i~ determined by proton-NMR in the following manne r:
The spectra are determined in deuterated ~-trifluoracetic acid ~olvent and using etramethylsilane -:
(TMS) as a ~tandard. The D.S. is determined by ~ntegrating th~ are~ due to the protons o~ carbons Cl -through C6 of the glucosamine derivative (6.0 to 3.0 ppm) ~nd comparing it with the total area due to the methyl :-group protons t2.~ to 2~0 ppm~ using the ~110wing ~ormula~
D.S. - ~M/~G/7))/3 ~ :.
where: M w ~rea of ~ethyl group protons -G ~ area of the pr~tons on carbons Cl ~.
through C6 of the glu~osamine ;
derivat iVQ
~he formyl pr~tons are observed at ~bout 8.4 ppm for the amide and at about 8.2 ppm for the ester. The D.S. of :
formyl groups is deter~;ned in a similar fashion using the oll~wing ~ormula: :
D.~. - F/(G/73 : ~ where: ~ - area of ~ormyl protons G - ~rea of the protons on carbons C
: through C6 Of the glucosamine derivative -.
~o de~ermine the relative:amounts of ace~yl ~nd ~ormyl :.
) ~ont~nt in the mixed derivatives both formulas ~re used.
~ ~XAMPLES
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RUN A
;~ ~ 35 Chitin was i~olated rom ~hrimp shells and spun ~ ~ in~o fiber according to the following prooedure~

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Isolation Df Chitin Shrimp shells obtained fr~m Gulf Citie~
Fisheries of Pascagoula, Miss. were placed in large container~ and soaked in aeetone for 5 to 7 days, after which the acetone was filtered off and the ~hells rinsed ~ with additional aoetone ~o remove as much pigment as possible. The hell~ were then air dried for 72 hours.
t ~he dried ~hells were ground into a flake using an Abbe cutter. The ground shells (500 ~) were deealcifi~d by treatment with ice oold 10% hydrochloric acid (4 to 6 1) . wath stirring for 20 ~inutes. The liquid was then removed - by filterang ~nd the ~hells rinsed wi~h water. This acid treatment was repeated and the dec~lciied shells were rinsed with water until neutral and allowed to air dry.
.: 15 ~he dry solid was suspended in 2.5 1 of 3% sodium hydroxide in a S 1 flask and heated at ~00C for 2 hours.
The uspension was then filtered and the remaining solid washed with w~ter. This causti~ treatment was repeated ~nd the ehitin obtained was washed with water until neutral. The chitin was then washed suecess~vely with ~ methanol and aceton0, air dried and lastly dried in a : v~cuum oven ~or about 12 hours at 120~C.
Spinnin~
Chitin ~btained by the ~bove procedure w~s di~solYed at 24~C in ~ 60/40 ~w/w) triehloro~cetic -- -acid/methylene chl~ride ~ixture, to form a ~olution containing 13.5% ~olids. The ~olution was tested and ound to be ~ni~otrop;c.
The chitln ~olution above was ex~ruded into ~ibers u~ing the apparatur represented by Fig. 1 and described previously. The ~olution was extruded through 0.004" diameter holes of a lO~hole 6pinneret at a jet velocity ~f 15.2 ~min., passed ~hrough a 1.25 cm air gap, into a ooe methanol bath and wound onto bobbins at a rate of 15.5 M/min.
~;ber properties were measured a~ described ~bove and are reported in ~able ~.
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: ' ~ 3 ~ 3 RUN B
~hitin acetate with a high degree of substituti~n of acetyl groups was synthesized and ~pun into fiber by the following method: -Preparation of_ Chitin Acetate 200 ml of reagent grade ~ethylene chloride, 400 ml of reagent grade acetic anhydride, and 125 ml of glacial acetic acid were added to a 1 1 resin kettle ~ -equipped with a ~tirrer and nitro~en inlet. The mixture ~ -10 was cooled to about 0C in a methanol bath and 20 g of -:
chitin, prep~red as in Run A, were added. 6 ml of 70%
perchloric arid were then added lowly and the mixture wa~
~tirred ~bout 12 hours. After ~tirriny, the ~ixture was filtered ~n a ~ritted Buchner funnel ~nd exc~ss acetic ~-15 anhydride was removed by ~spira~ion. ~he solid was washed . .
thoroughly with aethanol, ~cetone, 10% ~odium bic~rbon~te, water, and las~ly acetone, after which the ~olvent was ~ removed ~y aspiration. The re~aining ~olid waC then air ,~ dried ~or about 12 hours to give 25 g of chitin acetate as ~ white ~olid. ~he inherent viscosity of the polymer was !~ 5.72 dl/g ~nd the degree of substitution was 2.g5.

Chitin ~cetate prepared by the ~bove procedure was ~pun as ln Run A u6ing the apparatus r~presented by .
~ 25 Fig. 2 with the different ~pinnning par2meters li~ted in .: T~ble 2. ~.
Fiber properties were measured as described -.
I ~bove and repor~ed in Table I.
'~ EXAMPL~ 1 3C Chitin acetate with a relatively low de~ree of ub~titution of ~cetyl groups on chitin was ~ynthesized -~
and 6p~n into fiber by the foll~wing methcd:
reparation o~ Chitin ~cetate 200 ml of reagent grade ~ethylene chloride, 35: 400 ~1 o~ reagent grade acetic anhydride, ~nd 1~5 ml of glacial acetic acid were added to a 1 1 re~in kettle , : . .

-12 ~A 3 h ~
, 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 Example 1, were added. 3 ~l of ~0%
perchloric acid were then added slowly and the mixture was 5 ~tirred about 12 hours. A~ter ~tirring, the mixt~re was ~ filtered on ~ fritted suchner unnel ~nd exce~s acetic anhydride was r~moved by aspiration. ~he ~olid was washed ::
thoroughly with methanol, acetone, 10% odium bicarbonate, water, and lastly acetone, after which all of the solvent was removed by aspiration for ~bout 12 hours to g~ve 25 9 ~f chitin acet~te as a white ~olid. The inherent viscosity of the polymer was 8.76 and the degree of ~ubstitution was 2.0 Sp~ .:
Chitin acetate prepared by the ab~e procedure was spun as in Run A using the apparatus represented by -~.
Fig. 2 w.ith the different spinnning parameter~ listed in Table 2.
Fiber properties were measured as described 20 ~bove and reported in Table I.
EXAMPLE: 2 Is~lation of Chitin ~et ~hrimp ~hell wasl:e l25 kg) was sorted manually to remove extraneous ~ubstances and boiled in 25 w~ter ~or 2 hour~ ~he shells were collected by ~acuum . :
filtration and plaeed into ohe~esecloth p~uches. Using one-hal of the batch at a time, the shells were then ~oiled in 2% NaOH ~50 l~ under a nitrogen atmosphere for 1 hour, collected, pressed out and washed once with water.
30 ~he ~hell~ were then boiled for 9 hours in 2~ NaOH (50 l) under nitrogen for a 6econd time, collected, pressed out, washed in water ~nd immersed i~ 50 l 10~ ace~ic aeid for -:
s 1 hour ~t ro~m temperature. The shells were collecte~ by ~iltration, washed twice more in water and pressed out.
35 They wer~ finally ~uspended in acetone (4 1), collected by : :

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, filtration, washed once m~re with clea~ acetone and allowed to air dry. The.yield was 1.2 kg dry chitin.
Preparation o Chitin ~cetate :
Chitin (SD g) prepared as described ~bove was :
_ 5 ground in two ~teps to pass khrou~h a 0.5 mm ~creen. ~he ~round chitin was placed in ~ Soxhlet extraetor ~nd extracted with acetone until the extract was ~lear. After :
air drying, the chitin powder was washed twice with .
methanol, pressed out a~d heated to 77C in 15~ methanolic - -~
potassium hydroxide for 1 hour under nitrogen. ~he powder was collerted by ~iltration, pressed out, washed once with ~-wa~er ~ollow~d by two w~shes in qlaeial ace~ic ~cad. : :
After the final wash, the powder was pres~ed out and ~uspended using ~thods described ~bove in cooled acetic ~5 anhydride ~500 ml~ and methylene chloride (500 ~13 cnnt~ining perchloric ~cid ~2 ~1) all at -22C. After 16 hours~ the temperature was raised to 13C and the ::~
r reac~nt~ allow~d to ~ir for ~n addi~ional 24 hours reaching a final temperature of lBC. The polymer was : .
collected by filtr~tion, pre~sed out and washed twice with methyl ~lcohol. The product was then washed once in 5%
sodium bic~rbonate, followed by twb washes in water and a final wash in aeetone. The product was dried in a vacuum :~
at 55~C. The yield was 57 g. D.S. - 1.4 bas~d on NMR
~naly~is.
Spinning Chitin acetate prepared as described above was ~pun u~ing the method of Run A and the equipment described by Fisure 1. The ~pinning ~olvent was 60/40 w/w trichloroacetic acid/methylene chloride. Pertinent ~pinning para~eters appear in Table II. -:~
:: ~iber properties were ~ea~ured a described ~bove ~nd ~ppear in Table IO : :

ChitiQ ~c~tate/formate w~s prepared from chitin ~nd then ~pun into iber by the following ~ethod:

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Preparation of Chitin Acetate/Formate 200 ml of rea~ent grade methylene ~hloride and 255 ml of formic acid (~5-9B%) were added to a 1 1 resin kettle equipped with a stirrer and nitrvgen inlet and _ 5 cooled in a refrigerated bath to O~C. 280 ml of aeetic anhydride were added to the bath, allowed to cool to 0C, ~nd then 20 g of chitin prepared as in ~un ~ were added, followed by the slow addition of 6 ml of 70% perchloric acid. ~he mixture was etirred for abou~ 12 hours at 0C.
The ~uspension was washed th~ro~ghly wi~h ~ethanol, ~cetone, 10% sodium bicarbonate, water, and la~tly aeetone. Af ter removing the sblvent by aspiration, the ~olid was aid dried for about 12 hours and yielded 24 ~ of chitin acetate/formate as a white ~olid.
The inherent viseosity of the polymer was 11.4 dl/g and the degree o~ ~ubstitution was 2.~/0.5 (acetyl/formyl~.
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I Chitin acetate/formate prepared by the above procedure was spun the same as in Run A using the apparatus represented by FigO 2 with the different spinnning pa~ameters li~ted in Table II~
~iber properties were measured ~s described a~ove and report~d in Table I.
EXAMPLE 4 . -. Chitosan acetate/for~late was prepared from chitosan which it~elf was prepared from chitin and then :~
the 6hitosan ~cetate/formate was spun into ~ibers, per the :~
followin~ procedures:
Preparation of Chitosan Shrimp ~hells were washed in aeetone ~nd ground into a flake as des~ribed in Run A. The washed and cut : ~hell~ ~310 ~) were then treated with ioe cold 9%
hydro~hlorie a~id ~2 1 water, 1 1 ice chips~ 1 1 37~ HCl~ :
: 35 in a lar~e container ~or 20 minutes. The ~olution was filtered and the re~aininy solid rinsed with water. This ' ~14- .
:, ' -. , acid treatment was repeated, af~er which the solid was washed with water un~il neutral and then washed wi~h acetone and finally air dried. The resulting solid was treated with 2 1 of S0% odium hydroxide at 100C for 2 hours. The suspension was filtered and the remaining - ~olid was rinsed wi~h water. ~his caustic treatment was repeated a second time and ~he ~olid was collected by filtrat7On, washed until neutral with water, and then -.
washed wi~h meth~nol and acetone and allowed to air dry.
This procedure yielded B6 9 of chitosan ~s a white ~olid.
The inherent viscosity of the chitos~n was 11.3 dl/g in 50% agueous acetic acid.
Preparation of Chitosan Acetate/Formate 750 ml o 95-9B~ formic acid and 40 g of :~
lS chitosan prepared above were added in a 4 1 resin kettle. -~
The mixture wa~ stirred under ni~rogen in a r~frigerated bath at 0C for 1~5 ho~rs until ~11 the polymer was di~solved.
. 250 ~1 o~ glacial acetic acid were then added a~d the mixture stirred until a homogeneous ~olution was obtained. The mixture was stirred an additi~nal 30 min- !
550 ml of reagent grade ~cetic ~nhydride were added and then the mixture was stirred for about 12 hour~ at 0C.
The resulting gel wa~ broken up ~nd ~oaked in methanol ~5 (6 liters) for ~ ~ew hour~ to precipltate the polymer~
The polymer wa6 ~iltered and the ~olid gel chopped in ~ ::
blender. The pr~cipitated polymer was washed thoroughly wîth m~thanol ~everal times, and then with ~cetone. The :-~olid was aspir~ted to remove ~xce~s ~olvent and then allowed to air dry overnight. The yield was 53 9 of chitosan ace~te/for~ate ~s ~ white ~olid.
The inherent visco~ity of the polymer was 10.8 dl/g ~nd the degree of ~u~stitution was 0.4/2.3 :.
cetylfformyl). -Chitosan ~cetate/formate prepared by the above procedure was ~pun ~s in Run A u~in~ the ~pparatus ~.
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represented by Fig. 2 with the different ~pinnnin~
parameter~ listed in Table II.
Fiber properties were measured as described above and reported in Table I.
E~MPLE S
^~ Chitos~n acetate/formate wa~ prepar~d according to the ge~eral procedur~ in Ex~mple 4 with the ch~nges noted below.
750 g of 95-98~ formic acid and 40 g sf chitosan . 10 were ~ixed in a 4 1 resin kettle at ODC. O~ce the ~hitosan was well dispersed 500 ml of acetic anhydride were added and the reactio~ allowed to ~tir for 95 hours ~t 0C. At that time the polymer was essentlally ~Dmpl0tely in ~olution and was ikiolate~ by precipitati~n into cold ~ethyl alc~hol ~6 liters ~ 0CI. The white product was collected by vacuum filtration, then w~shed -~-twice with water, followed by another wash in methyl ~lcohol and a final wash in acetone. The product was all~wed to ~ir dry yielding a white fibrous ~olid.
~}~ 2 .
Chitssan acetate/~ormate prepared by the above .pr~cedure w~s spun using the method of Exampl~ 1 ~nd the equipment described by ~igure 1. The spinning solvent was 49:51 w/w trichloroacetic acid/~ethylene chloride. Other pertin~nt Rpinning parameters appear in T~ble II.
Fiber properties were measur2d as described ~ : above and app~ar in Table I.

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~ABLE I

FIBER PROPERTIES
D~So ACETATE/ TENSILE PROPERTIES ::
EX. DESCRIPTION FD~MATE DPF IEN./ELCNG./M~D.
A Chitin 1.0/0.015.7 1.3gpd~2.6%/107gpd B Chitin 2.9/0~0 7.0 2.~gpd/7.3%~0gpd Acetate 1 ~hitin 2.0/0.0 4.5 4.3ypd/4.5~/169gpd Acetate 2 Chitin 1.4 5.4 5.9gpd/~.4%/206gpd Acetate 3 Chitin 2.0/0.3 5.1 5.9gpd/6.8%/162gpd Acetate/~vrmate 4 Chitosan 0.4/1.4lg.1 7.0~pd/6.8%/194gpd Acetate/Formate Chitosan 0.3/1.521.4 6.2gpd~.8%/185gpd Acet~te/Formate :-D.S. ~ degree of sl~bstitution, tlhese fiber v~lues can differ from those ~ -of the starting polymer because ~ome partial deesterification may oecur during conversion to fibers DPF ~ denier per filament Ex. - Example or run designatio:n :: '" ', :
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q~BLE I I
SPINNING P~MET~5 Parameters Run A Run ~ 2 Ex. 3 ~x. 4 Ex. 5 Solids 13 . 5% 15% 15% 15% 15% 17% 15%

N~. c f ~oles 10 1 1 5 1 1 20 Dia. of ~oles 0.0102 0.0076 0.0076 0.0076 0.0076 0.0127 0.0076 ~ ~n) ,- ~ ,;
Jet Velocity 15.2 29.9 16.6 1.5 20.0 12.û 3.4 - .
(M~Snin) - ~ -A~r G~p (an) ?o25 1~4 1~ 3 1~4 1.0 1.9 ;~
(:oagulation ~ath 0 1 8 16 -20 5 Temp. ( C) -Wind-up Rate 15.5 24 40 21.3 17 9.9 6.8 - :::.
(M~min~

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Th~s~applica~ion is a division o~ Canadian application serial no. 554,034 fll~e~d~ De;cember 10, 1987.

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Claims

1. Poly-N-formyl-N-acetyl-O-acetyl-O-formyl-D-glucosamine wherein the O-acetyl and O-formyl substitution occurs at the 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, and a degree of formylation ranging from about 0 to 2.0 and wherein the degree of acetylation of the N-acetyl substitutes ranges from about 0 to 0.75, the degree of formylation of the N-formyl substitution ranges from about 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.

2. The polymer of Claim 1 wherein the degree of O-acetylation is 0.1 - 0.5 and having a degree of N-acetylation less than 0.2, a degree of N-formylation of 0.2 - 1.0 and a degree of O-formylation of 0.5 - 1.5.

3. A fiber of the polymer of Claim 1.

4. The fiber of Claim 3 having a degree of O-acetylation greater than 0.05.

5. The fiber of Claim 4 having a tenacity of at least 4 g/den and a modulus of at least 100 g/den.

6. The fiber of Claim 5 wherein the tenacity is for the as-spun fiber.

7. The fiber of Claim 6 wherein the as-spun tenacity is at least 6 g/den and the as-spun modulus is at least 150 g/den.

8. A process for making a chitosan acetate/formate polymer comprising the steps of adding formic acid acetic anhydride and acetic acid to chitosan.

9. The process of Claim 8 further comprising spinning the polymer into a fiber whereby the fiber has as-spun tenacity of greater than 4 g/den.