CA1251880A - Substantially homogeneous polymer solution in tertiary amine n-oxide and process for directly extruding same into non-solvent bath - Google Patents

Abstract

SUBSTANTIALLY HOMOGENEOUS
POLYMER SOLUTION IN TERTIARY AMINE N-OXIDE
AND PROCESS FOR DIRECTLY EXTRUDING SAME INTO NON-SOLVENT BATH

ABSTRACT OF THE INVENTION

A new and useful substantially homogeneous extrudable solution of a base material, e.g., cellulose, is disclosed, comprising (a) a predetermined amount of each of two or more tertiary amine oxides, each of which is in a known state of hydration and each having a known melting point, to form an initial mixture, the tertiary amine oxides selected from the group consisting of N,N,N-triethylamine N-oxide; N,N-dimethyl-cyclohexylamine N-oxide; N-methylmorpholine N-oxide; N-methyl-piperidine N-oxide; N-methylhexamethyleneimine N-oxide;
N,N-dimethylbenzylamine- N-oxide; and N,N-dimethylethanolamine N-oxide, said amount of each sufficient to depress the melting point of the initial mixture below the melting point of each of said tertiary amine oxides in their known state of hydration and to form said liquid; (b) a predetermined amount or a base material added to said initial liquid mixture, the base material selected from the group consisting of suitable water soluble polymers, nylon, cellulose and other polysaccharides, and (c) water, including but not necessarily limited to the hydrated water above, whereby the amount or initial mixture or tertiary amine oxides (a) is sufficient to dissolve the base material and to form a substantially homogeneous extrudable solution, and the amount of water (c) is just sufficient to provide the dissolved I

base material with a predetermined melting point. Preferable combinations of tertiary amine oxides include N-methylmorpholine N-oxide ("NMO" or "NMMO") and N,N-dimethylethanolamine N-oxide ("DMEAO"); NMO and N,N-dimethylcyclohexylamine N-oxide ("DMCAO");
and DMCAO and DMEAO. The novel substantially homogeneous extrudable solutions find particular utility in that they may be directly extruded into non-solvent baths to avoid significant mechanical problems of air gap spinning and to avoid significant cellulose/base material degradation inherent in prior art techniques because of exposure to high temperatures; at the same time the process of the instant invention reduces energy costs.
After extrusion, the base material extrudate, e.g., cellulose base material, may be dried in normal fashion to produce a novel product, e.g., membranes.

II

Description

~5~8~11) ., ~

Il AEC1481~ 1 ',I I
1 SUBSTANTI~2~LLY E~OMOGENEOUS
!POLYMER SOLUTION IN TERTIARY AMINE N-OXIDE
AND ?ROCESS ~OR DIRECTLY EXTRUDING SAME I~TO NON-SOLVENT 3~TEI

¦l. Field of_the Invention This invention relates to the use of amine-oxides as solvents for cellulose and other base materials whlch can be similarly dissolved therein, and particularly to the use of certain co-solvents in cellulose tertiary amine ~-oxide solutions pioneered by Franks and coworkers, U.S. Patents 4,196,282 and 4,185,532 and their progeny, and to the processing improvements in extrusion for those tertlary amine oxides of McCorsley III, U.S. Patent 4,144,080 and its progeny. The invention also relates to the fieid of cellulosic membranes produced by extrusion.

2. Descri~tion_of the Prior Art, and Other_Information In the past few ye~rs, amine-oxides as sol~Jents for cellulose have been the focus of several studies. Such use of ¦ amine oxides was first reported in the late 1930s, e.g., Swiss 1 Patent 191,822 and more particularly, Graenacher et al., U.S.
¦ Patent 2,179,181 ~1939).
, In accordance ~ith the '181 disclosure, oxides of ¦ trimethylamine, triethylamine, tripropylamine, monomethyldiethyl-¦ amine, dimethylmonoethylamine, monomethyldipropylamine, ~l-dimeth-`
1 yl, N-diethyl or 2~-di~ropylcyclohexylamine, N-dimethylmethyl-cyclohexylam.ine and pyridine may be used. Graenacher report;, relatively low solid solutions cont~ining from 7 .o 10~ bv ~7eight i ! ~ 5~

o cellulose dissolved in 93 to 90% by weight of the tertiarv amine. Graenacher does not disclose any such solutions having a high solids content, i.e., in the range of 10-3;~. Graenacher makes no mention of the necessity and c iticality for the inclusion of water in the solution.

! Another process for dissolving cellulose or other compounds having strong intermolecular hydrogen ~onding in a tertiary amine oxide is disclosed by Johnson and the Eas.man Kodak team in U.S. Patent 3,447,939. A cyclic mono (N-methyl-amine-N-oxide) compound such as N-methylmorpholine-N-oxide (~MMO) is used as the solvent. The solution can be used in chemical reactions involving the dissolved compound or to precipitate the ¦
cellulose to form a film or filament. In accordance with the ¦ process, the solution is maintained as a liquid until it is used.
1~ l The resulting solutions, insofar as the actual examples of the ¦ patent indicate, have much the same disadvantages o those ¦ prepared by the process disclosed in U S. Patent 2,179,181 above, ¦ because they are also of low solids conte.~t and have a high I viscosity.
¦ In accordance with the process disclosed in U.S. Patentl

3,508,941, also to Johnson (and its British counterpart, 3ri~ish ¦
Paten' 1,144,759), two or more different polymers are dissolved in a cyclic mono(N-methylamine N-oxide) compound and are precipitated together to produce a bicomponent polymer mixture.
2~ I A diluent such as dimethyl sulfoxide, N-methylpyrrolidone or sulfolane may be added to tne solution as a diluent to ~educe i s~
viscosity. The solutions also have the same deiciencies no.ed or the irst mentioned Johnson patent, as well as U.S. ?atent l 2,179,181. See also U.S. Patent 3,;03,700 .o ~riggs, ~ertaining 1 ¦ to a ,lethod tor lmprcvlng th~ we~ streng~n, dry str-tch and :~,?5'18.'30 resistance to ~enetration by liquids of unsized ~aper ~y lmbibing l1the pa?er with an am ne oxlde, capable of swelllng the ?aper ,¦fibers and a ketene dime~ paper sizing agent, heating the pape-I¦_o swell ~he ~ibers and removing the amine oxide rom the paper by vaporization, washing, or solvent extraction~
Of course, Graenacher's amine oxides were not the or.ly sclvents utilized in the prior art to dissolve cellulose, viz., U.S. ~atent 4,028,132 wherein hydrazine is employed; note also ! Bockno et al. V.S~ Patent 3,277,226.
0 ¦ ~owever, the commercial success of the use of amine oxides was assured when Franks and coworkers were a~le to obtain concentrated cellulose solutions (>10~ cellulose). See (1) U.S.
Patents 4,145,532 (1979) and 4,196,282, using selected tertiary amine oxides, and (2) their progeny, U.5. Patents 4,1~2,913;

4,144,080 and 4,246,221, all to McCorsley III, relating to processing by extrusion and air gap spinning, and (3) U.S.
Patents 4,284,545; ~,256,613; 4,255,300; 4,2~7,431 and 4,247,688, all to Franks and Varga, relating to alternative base .materials other than cellulose alone. Note also U.S. ?atent 4,324,593 to 0 Varga relating to an improved solvent utilizing both a ter~iary amine oxide and an al~aline compound which increases the rate at which the cellulose dissolved in the solvent, and ~.S. P~t~nt 4,290,815 to Henry directed to the use of co-solvents miscible with cellulose dissolving amine ~-oxides, containins primary and secondary amino groups wherein the amlno groups are bonded to al.~yl, alicyclic, dialkyl ether or alXyl/alicyclic groups and , wherein the number of carbon atoms divided bv the number of primarv amino groups equal to or less than 4, or -C/~NH2<4, and 'he number of primary amlne groups divided bv the number o l '~
l ll ~1 -3-1~

seconda-~; amine g-oups is equal to or greater than 1; or ~N~2~Nd~>l~
~ ecently, several scientific papers have ap~eared in the literature describing diferent aspects of the amine oxide ¦ cellulose system. Chanz~ ec al. have reported results on the crystallization of amine oxide-cellulose solutions. See Chanzy, . Dube and R. H. Marchessault, J. POLYMER SCI. (Polym. Let.
Ed.) 17 at 219-~26 (1979). Generally, cellulose dissolves in 1 certain amine oxides at elevated temperatures (>70C); see ¦ U.S. ~atents 4,145,532 and 4,196,282, supra. Most amine oxides are hvdroscopic and generally display a series of crystalline hydrates liXe N-methylmorpholine-N-oxide (NMMO); E. ~aia, A. Peguy and S. Perez, AC~A CRYST. B37 at 1858 (13a1). The melting point of the hydrates are inversely related to the water content. See ~. Chanzy, S. Nawrot, A. Peguy and ~. Smith, J. POLY. SCI. (Polvm. Let. Ed.) 20 at 1909-1924 (1982), not admitted to be prior art herein. Solutions of 5~ or more cellulose in a given amine oxide can be obtained only if the 1 water content is less than a given value. At these water ¦ contents, the individual amine oxides are solid at room temperature. Therefore, it has been necessary by Fran~s and cowor~ers to accomplish the diss~lution of cellulose in these single amine oxide solutions at elevated temperatures. Upon 1 cooling the solution to room 'emperature, solidification of the 2~ ¦ solutlons occurred from the crystallization of the amine oxide solvent. In 1979, this crvstallization was indicated at tha.
time to be a novel method of texturing cellulose; see Chanzv ~t al. (1979), su?ra.
¦l A liquid amine oxide solvent c~n be obtainQd at roo~
39 1 temperatu-e. It was reported recently t;1at ~ne adci~ion of l ll dimethvl-ormamide to triethvlamine-N-oxide produced a ao'ven~
¦I that .emained liquid at room temperature; L. ~. Gonoboblev and G. A. ?et-opavlovskii, Z~U~NAL PRIKLODI~OI KI~ 3(10) at 1 2309-2313 (1980). Swelling of the cellulose occurred at room ; I temperature and dissolution was completed bv heating to 80C.
Upon cooling to room temperature, the solution would either form l transparent gels or show a phase separation according .o the I amount of diluent (dimethylformamide). The phase separation consisted of bïrefringent spherulites that could be concentrated by centrifugation. The spherulites rich fraction possessed a crystalline structure as detected by x-ray.

3. State of the Art A liquid amine oxide solvent can also be obtained by combining amine oxides. An example of such a solvent is the ¦ combination of N-methylmorpholine-N-oxide (N~MO) and N-~-dimeth-ylethanolamine-~-oxide (DMEAO). For example, at a weight -atio DMEAO/N~MO of 3, the mixtures are liquid at room temperature wilh water content as low as 12% (w/w). Chanzy et al. reported ¦ swelling of cellulose in the mixtures at room temperature bu.
¦ dissolution occurred only when heated above 60C. See a. Chanzy, S. Nawrot, A. Peguy and P. Smith, "Phase Behavior of the Quasiternary System N-Methylmorpholine-N-oxide, Water and Cellulose", J. POLV. SCI. 20 at 1909-1924 (1982), not admitted to ~ be prior art 'nereto. No mention was made of ~he solution 11¦ behavior upon cooling to room temperature.

I 4. Miscellaneous I _ A. the Ninth Cellulose Conference, Mav 2'-27, 19&2, at ¦ 'he State University o- New Vork, College o~ ~nvironmenta1 ¦ Science and Forestrv, S-Y_aCUSe, New York, a lecture and paper andouts were presented ~y ~ r~zy and coworkers or .he C-nt-e de ~echerches sur les ~acromolecules Vegetales (Grenoble, France) il entitled "Sweliing and Dissolution of Cellulose In Amine Oxide/
I Water Systems". Specifically, in the paper handout at pages 4, 10, 11, and 12 and Figures 5-6, one solution embodiment of the invention--a NMMO-DMEAO solution--was discussed. The disclosed embodiment reported by Chanzy and coworkers was derived and obtained by them solely from present applicants.

5. Problem ~aced by Applicants Prior art solvents containing a single tertia.y amine N-oxide were by no means perfecl for dissolving cellulose.
Mixtures containing these solvents and cellulose (1) needed a l great amount of water in order to liquify the solvent containing ¦ the cellulose, and further, (2) had to be heated to a slgnificant temperature--90C to 140C or higher followed by the necessarv ¦ steps to remove the water to obtain a [homogeneous] solution, all ¦ of which took substantial amounts of energy. See U.S. Patents ¦ 4,144,080 (column 3, lines 1-28, and in particular lines 5-7, and ¦ Example III); 4,246,221 (in particular, column ;, lines 22-32 and~
Examples III(a)-III(e)); and 4,290,815 (column 2, lines 22-3a and~
Examples III-I~1). Note also that the prior art cellulose solutions in single tertiary amine ~-oxide solvents require air-gap spinning (note Figures of U.S. Patent 4,246,221) which ?resented significant problems to ~he artisan, e.g., sticXing o~
the tilaments af.er extrusion in the air gap, tangling and touching, etc. Wet spinning, when practical, has always been preferred bv artisans in polymer solution extrusion. See U.S. ?atent 3,842,151 to Stoy et al.

~1 ~urtnermore, there has been a long felt need for zn ,¦ ideal sol~ent for cellulose and other simllar acting base mate-Il ~ials. ~n ideal solvent would have the following requi-emen.s:
i (1) i. would be 2 liquid at room temperature;
j (2) it would be a non-solvent at room temperature and would be a good swelling agent;
~3) it would become a solvent upon lncreasing temperature with little or no water removed;
(4) in slurry form, with a cellulose or othe~ base material, the slurry would be of low viscosity; and t5) the solvent would be of low toxicity and relatively easy to recover. I
ll Solvents of the instant invention, es?ecially those mix~_u es of 1~ NMMO and DMEAO, appear to virtually fulfill the requirements. A
significant advance in the art has therefore occurred.

SUMMARY OF T~E INVENTION
A substanti211y homogeneous extrudaole solution of a base material has been made, comprising:
(a) a predetermined amount of each of two or more tertiary ~mine oxides [i.e., constituents, each tertiary amine oxide], each of which is in a known state of water hydration and each having a known melting point, to form an inirial liquid mixture, the tertiary amine oxlde selected from the group con 2~ sisting of ~,N,N-triethylamine N-oxide; N,N-dimethylcvclohexyl-amine N-oxide; N-methylmorpholine N-oxide; N-methylpiperidine ¦ N-oxide; N-methylhexamethyleneimine N-oxide; N,N-dimethvl~enzyl-amine N-oxide; and N,N-dimethylethanolamine N-oxide, said amoun.
¦ of each sufficient to depress the mel,ins point of the ini~i21 _-,_ ~5~

mixture below the melting point of each of said tertiary amine oxides in their known state of hydration and to form said liquid;
(b) a predetermined amount of a base material added to said initial liquid mixture, the base material selected from the group consisting of suitable water soluble polymers, nylon, cellulose, and other polysaccharides; and (c) water, including but not necessarily limited to the hydrated water above, whereby the amount of initial mixture of tertiary amine oxides (a) is sufficient to dissolve the base material and to form a substantially homogeneous extrudable solution, and the amount of water (c) is just sufficient to provide the dissolved base material with a predetermined melting point.
A preferred base rnaterial is cellulose. Note, however, other suitable base materials of U.S. Patents 4,247,688; 4,255,300i 4,256,613; and 4,284,546. Other base materials will be recogn~zed by those of ordinary skill in the art.
DESCRIPTION OF THE DRAWINGS
Figure 1 constitutes an illustration of a phase diagram of NMMO/DMEAO mixture at room tempera.ure.
Figure 2 constitutes an illustration of the maximum water content for 10 and 20~ cellulose solution in NMMO/DMEAO
mixtures.
Figure 3 is a schema-tic diagram of two process alter-natives where the base material is cellulose for arriving with-in suitable conditions (tempera-ture greater than 70C; water content less than 15~) tc ach ~~_ a Ivlrlogerleous extrudable solution.

Figure 4 com~rises three thermograms of novel cellu-lose spherulites before and after crystallization (see Example 8).
Figure 5 comprises three X-ray diffractograms of novel cellulose spherulites before and after crystallization (see Example 8).
Figure 6 is a schematic of an embodiment which may be used for wet spinning.
Figure 7 comprises a graph indicating maximum draw ratio as a function of velocity at spinnerette for wet spinning using a. DMEAO/NMMO ratio of 3:1.
Figure 8 comprises a schematic indicatins maximum drawability in a precipitation bath as a function of extrusion velocity.
Preferable combinations of tertiary amine oxides to the initial liquid mixture include (1) N-methylmorpholine N-oxide (`'NMMO" or "NNMO") and N,N-dimethylethanolamine N-oxide ("DMEAO"); (2) NMMO and N,N-dimethylcyclohexylamine N-oxide ("DMCAO"); and (3) DMCAO and DMEAO.
The synergistic effect of each of these groups of two or more tertiary amine cxides for the initial liquid mixture is to utilize same in an area of their mixtures sufficient to depress the melting point of said mixture below the melting point of each of said tertiary amine oxides for a given state of -8a-hyd~ationJwater content. For a given state of wa~er hyd_ation~
ate~ cQntent ror the ter~iary amine oxides taXen individually or in combination as a llquid mixture, the mel~ing ~oint is a Il function of the water content. For example, lr the tertiary ! amlne oxides ~orming the initial mixture above comDrise ~meihyl-l morpholine N-oxide and N,N-dimethylethanolamine N-oxide (DMEAO), ¦
where the water of hydration for DMEAO is about 10.~% and the i wa~er of hydration for NMMO is about 27%, as shown in Figure 1, inf~a, the weight fraction selected of ~-methylmorpholine N-oxide to N,N-dimethylethanolamine N~oxide in the initial and liquid mixture should be about from 0.15 to about 0.5, and most preferably in the range of about 0.25-0.3. ~sing this preferred combination of NMMO and DMEAO, a much preferred substantially homogeneous extrudable solution for cellulose may be obtained wherein cellulose i~ from 5 to about 20~ by weight of said solution, and the total amount of water is from about 5% to about 10% by weight of said solution.
As an alternative to NMMO and DMEAO, one may also select an initial mixture comprising N-methylmorpholine N-oxide o I and N,N-dimethylcyclohexylamine N-oxide, wherein the weight raction of N-methylmorpholine to N,N-dimethylcyclohexylamine is ¦ from about 0.3 to about 0.7. Using this combination of ~MO and DMCAO, a preferred substantially homogeneous extrudable solution for cellulose may be obtained, wherein the cellulose is from ~5 1 about 5% 'o about 20~ by weight of said solution, and the total amount of water is from about 10~ to about 1~ of said solution.
~s a third ?referred embodiment, one may choose a com-~ bination of tertiary amine oxides comprising N,N-dimethylcvclo-¦¦ hex~lamine N-oxide and N,N-dimethylethanolamine N-oxide, wherein the weigh. fraction of N,N-dimethylcyclohex~ylamine ~o Il l ~,N-~imethylethanolamine N-oxide ls from about 0.1~ to about O.S0, ana most preferably about 0.25-0.3. In this third prefer-ed embodiment. a substantially homogeneous ext-udable l solution for cellulose is present where the cellulose is from S ¦ about 5~ to about 20~ by weight of said solutlon, and the total amount of water is from about 5~ to ab~ut 10~ by weight of said solution.
Of course, many other combinations are possi~le of the seven indicated tertiary amine N-oxides, and one may certainly use more than two tertiary amine N-oxldes at any one time.
Experimentation to obtain these combinations is routine and well within the skill of those in the art.
Using these novel solutions, a direc-t wet mix process can be achieved. This process for manufacture of a substantially¦
homogeneous extrudable solution of a base material having a predetermined melting point comprises the following st-ps:
(a) mixing a predetermined amount of each of two or more constituent tertiary amine oxides, each of which is ln the known state of hydration and each having a known melting point, to form an initial mixture, the tertiary amine oxide selected from the g.oup consisting of N,N,N-triethylamine N-oxide;
N,N-dimethylcyclohexylamine N-oxide; N-methylmorpholine N-oxide;
N-methylpiperidine N-oxide; N-methylhexamethyleneimine N-oxide;
N,N-dimethylbenzylamine N-oxide; and N,N-dimethylethanolamine 25 ¦ N-oxide; said constituent amounts of amine oxides sufricient ~o depress the melting point of the initial mix ure ~elow the melting points of each of said tertiary amine oxides in thei~
known state of hydrati.on and to form a liquld;

~1 ~o ~ ~3~

(~) water, inclusive or the water o~ hydration of said ter~iary amine oxides, sufficient to bring the water content of , the inl~ial mi~ture (d) to a predeter~ined amount;
(c) adding and mixing a predetermined amount of a base~
material selected from the group consisting OL suitable polymers, . I nylon, cellulose, and other polysaccharides with said initial aqueous mixture of tertiary amine oxides to form a slurry; and (d) mixing the slurry until the substantially l homogeneous extrudable solution of the base material having a ¦ predetermined melting point is achieved.
A preferable base material is again cellulose, and it is further preferred for cellulose that the initial mixture (a) specified above be less than 15% by weight. Preferably, the water is adjusted following the formation of the initial mlxture to a predetermined/sufficient degree to provide the initial mixture with a higher/lower and predetermined water content, in any event less than about 15~ by weight water. One preferred sequence is that the aqueous solvent initial mixture be added to the base cellulose material at a temperature for about 20~C to ¦ about 60C to for~ a slurry, and that thereafter the slurry be heated and mixed until the slurry is about 70C or more until a substantially homogeneous extrudable solution of the cellulose material is achieved. See Figure 3, Route A. At temperatures ~ above 70C, a compromise must be chosen by ,he artisan bet~eQn 2; ~ the time taken to achieve homogeneity and the ever-increasing danger or degradation of the cellulose.
Where the base material is cellulose and the amount of water of the initial mixture (a) ends up to be gr-a~er than 1~, l one may heat and mix the slurry until the slurrv is above 70'C
1 and then remov~ a sufficient amount of water until 2 su~stantial-1~ ~11-¦ ly ~omogeneous extrud~ble solution of the cellulose material ia achieved. See Figure 3, .~oute 3. The object is, as always, for the cellulose base material to obt~in conditions where the amoun~
of wa~er in the tertiary amlne oxide-water-cellulose solu~1on is less than 15~ and the temperature is greater than 70'C. One may ~¦ therefore also envision an alternative of:

!l ( a) heating up the initial mixture (a) from a ~emper-I ature of about 20C to about 60C until the initial 'emperatu-e l of the initial mixture (a) is greater than 70C; then 0 1 (b) adding and mixing a predetermined amou~t o~
cellulose until a substantially homogeneous extrudable cellulose solution is achieved.
As previously mentioned, the combinations of ~MMO and DMEAO (wherein the N-methylmorpholine ~-oxide is present in a ~5 ¦ weight fra~tion of about 0.15 to about 0.5, most preferably in the range of 0.25-0~3); NMMO and DMCAO (most preferablv ?resent in about equal amounts); and DMCAO and DMEAO (most preferably ¦ wherein the N,N-dimethylcyclohexylamine N-oxide is ?resent in a weight fraction of 0.1~ to about 0.5%, most preferably about ¦ 0.3%) are available.
Once the substantially homogeneous extrudable solution has been obtained, it can be cooled gradually to a temperature below about 70~C to provide a .~etastable aqueous cellulose solu-~ tion capable of immediate extrusion. Spherulites or cellulose 1 can be obtained from such a metastable cellulose solution. The cellulose chains adopt a radial arrangement in the spherulites.
¦I The growth induction period and size of the spherulites are controlled mainly by cellulose concentration and temperature of ¦ solution. These s?herulites represent a new ~hysical form o~~
I cellulose ~ith a non-fibrous morphology. See Ex~mple 8.
'~ I

~ 5~

Where ~ellulose is the base material, 2 new and ext-emely useful d rect wet mix process is achieved for e~truding a solu-ion o cellulosic materlal in a solvent comprisng two or il more suitable tertiary amine oxides, comprislng: j ~ (a) dissolving in a predetermined amount of water a ¦ cellulosic basic material selected f~om the group consisting of i cellulose, cellulose and any other polysaccharides, cellulose and ¦ any other water soluble polymer, and cellulose and nylon ln I solvent mixture comprising two or more suitable tertiary amine !0 oxides selected from the group consisting of N,N,N-triethylamine ¦
N-oxide; ~,N-dimethylcyclohexylamine N-oxide; N~methylmorpholine N-oxide; ~-methylpiperidine N-oxide; ~,N-methylhexamethyleneimine~
N-oxide; N,N-dimethylbenzylamine N-oxide; and N,N-dimet~ylethan-olamine N-oxide to form a substantially homogeneous extrudable solution of said cellulosic basic materials; and (b) extruding said substantially homogeneous solution from about 20JC to about 60C directly into one or more se-¦ quential precipitation baths, each of which comprises a non-l solvent to said cQllulosic basic material, for sufficient ~ime to ¦ remove substantially all the tertiary amine oxides from said cellulosic basic material. Preferably, the cellulosic basic ¦ material comprises cellulose alone, in which instance the bath may be maintaned from about 20C to about 80C.
¦ For this novel process of direct extrusion, the non-1 solvent for the cellulosic base material may be ~referably selected from the group consiatlns or water, methanol, ethanol, propanol, isopropanol, and N-but~nol. Again, ~referred combinations of tertiary amine N-oxides include (1) NMMO and ll DMEAO; (2) NMMO ~nd DMCAO; and (3) DMCAO and DM~O in the above 1¦ indicated ~elative amounts. ~here a combination of tertiar-~

:i , ~ l l I¦ amine ~-oxides is chosen to be NMMO and DMEAO, it is ?re-e_~ed I t.hat the water ?resent ln the celluosic basic material ~immediately before extrusion be about 10~ to about 13~ by welght.
jl~here ~he combination of tertiary ami~e N-oxides is chosen ~o be i ¦~MMO and DMCAO, the amount of water present in the cellulosic ¦base material immediately before extrusion should be about from I 11% to about 13% by weight. ~inally, where the combination of tertiary amine N-oxides is chosen to be DMCAO and DMEAO, t~e l amount of water present in the cellulosic base mat rial ¦ immediately before extrusion should be about 12~ by weight.
As stated above, the direct wet mix process of the instant invention involves extrusion of the substantially homogeneous solution directly into one or more sequential precipitation baths, each of which comprises a non-solvent to said cellulosic basic material, for sufficient time to remove substantially all ~he tertiary amine oxides from said said cellulosic base material to form a wet swollen cellulose extrl~date having pores which ent~ap water.
Following such an immersion in these baths, .he wet O ¦ swollen cellulosic extrudate may be dried to form a novel cellulosic base material product. Drying may be accomplished by a number of means, all of which are well-known to those skilled i in the art. In one embodiment, the wet swollen cellulosic l extrudate may be immersed prior to drying in a second non-solvent bath, comprising one of the group consisting of a a non-volatile compound dissolved in a volatile liquid, whereby the liquid is ! capable of being exchanged for the entrapped water in the pores ! of the wet swollen cellulosic extrudate. Arter elinination of ¦ the volatile liquid, mainly the non-volatile compound remains.
;O I Prefera~ly, the second non-solvent bath aforementioned comprises :

Il .

glycerine and wat.er, most preferably where the weight ra-tio of glycerine to water is about l:3.
In a second embodiment, the wet swollen cellulose extrudate may be freeze-dried in the normal manner to remove the entrapped water from the pores while preventing the collapse of said pores.
In still ano-ther embodimen-t, -the wet swollen cell-ulosic extrudate may be immersed prior to drying in a second non-solvent bath, said second non-soLvent bath comprising a non-polar volatile solvent, whereby -the non-polar volatile solvent is capable of being exchanged for said entrapped water in the pores of the wet swol~en cellulosic extrudate, to form a non-polar volatile solvent swollen cellulosic ex-trudate, followed by air drying said non-polar volatile solvent swollen cellulosic extrudate to remove the entrapped non-po:lar volatile solven-t from the pores whi.le preven-ting collapse of said pores.
As aforementioned, once again for manufacturing of the novel dried cellulosic product, i-t is preferred that the combination of tertiary amine N-oxides be chosen from (l) NMMO and DMEAO; (2) NMMO and DMCAO; and (3) DMEAO and DMCAO in the aforementioned relative amoun-ts.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The inst;ant cellulose tertiary amine N-oxide system offers much more than process improvements in textur-ing cellulose, and will be useful applica-tions for the development of new products and technologies for cellulose, e.g., membranes and films. See West Ger. Appl. DE 30 21 943Al, incorporated herein. Production of small spherulites of cellulose is another physical form op-tion that could have potential commercial value in various technology applications, such as capsule Eormation or chroma-tography subs-trates.
Colloidal dispersions of small cellulose spherulites are accessible via this approach. The system herein offers promises for other kinds of particulate texturing since only physical phenomena are involved in the precipitation/

, (CONT'D. O~ ~EXT PAG~) ' .

~l~J~"~3~
~crys~alll,~tion process compared to the chemical regen~ration aspect of the viscose process.

WET SPINNING
_ !
~ Figure 6 depicts in schematic ~orm process equipment j for spinning: material from solution holding vessel 1 is fed into a pump block 2 to spinnerette 3 immersed directly in non-solvent bath 4 and is drawn in spin bath ~ by godet ~.
We have performed such wet spinning using an initial l preferred liquid mixture comprising NlYMO:DMEAO (weight ratio 0 ~ about 1:3) with excellent results.
The same limiting factors involved in solution preparation, extrusion through the spinnerette and obt ining the desired fineness of known tertiary amine N oxide processing of cellulose (see U.S. Patents 4,152,532 and 4,196,282 and their progeny, ~E~) generally apply. One additional limit imposed by wet spinning is the maximum allowable pressure behind the spinnerette. Gold-platinum viscose rayon t~pe spinnerettes were used and have a maximum pressure limit of 150 psi (for spinnerettes evaluated). These spinnerettes were used because of 0 expediency rather than necessary materials of construction.
Due to a 150 psi limit on our spinnerette, the following solution composition ranges give solutions wi h acceptable solution processing viscosities.
Cellulose Concentration 5-15~
Molecular r.~eight (IV) 300-600 (1.;-3.0) water Content 9-12 DMEAO/NMMO Ratio 3:1 i ' i~ -17-11 l i~2 5~

et spun cellulose solutions can be drawn to the ¦desi~ed fineness in the spinbath, depending upon the bath composition, bath temperature and spinnerette hole size.
,j The curves presented ln Figure 7 show an lncrease in l~maximum draw ratio as the bath temperature increases. When the maximum draw ratio versus extrusion velocity is plotted, the maximum draw ratio is lndependent of hole size (60ll versus 1lOu).
The data plotted in Figure 7 were made using a 7~
I cellulose solution with a DMEAO:NMMO ratio of 3:l and a water O ¦ spinbath.
The amine oxide(s) content of the spinbath can be 0-40%. At amine oxide(s) content greater than 40~, the solution forms a weaX gel that cannot withstand the forces exerted by l drawing.
S ¦ The maximum draw ratio versus extrusion velocity curve ¦shown in Figure 8 shifts in the direction indicated if one of the ¦variables listed below is changed while the remaining variables are held constant:
(a) increasing one or more of the following variables 'O I causes the curve to shift left:
(1) cellulose concentrations (2) cellulose molecular weight (3) amine oxide concentration in the bath (b) increasing the spinbath temper~ture causes the curve to shift upward and to the right.
Since the output is restricted by cellulose concent_ation, hole size, extrusion velocity, desired fineness ~ and humber of holes, the artisan will now recognize that a ¦ trade-off exists belween the higher spinning s~eeds or air ga?
splnnirg verrus tne hisher hol? density oE wet salnning.

Il - 1 8-Dr~w ratios of up to 10 can be achieved in the ¦spinbath. No improvement in maximum draw ~atio has been made by using additional baths and st~etch godets. ~rawlng a ter 'he first spinbath seems to be independent of additional st-etch ; I conditions (e.g., air at 25C, bath concentrations o. 0-60 tertiary amine W-oxide(s) or bath temperature) If the draw ratio in the first spinbath is reduced, then the ability to stretch bet-~een godets increases slightly. However, the total draw ratio (initial + stretch between godets) is less than that 0 attainable in the first bath alone.
Wet spun fibers according to our invention exhibit die swell. Undrawn fibers extruded into a 75C spinbath had a die swell o~ approximately two times. The die swell of the wet spun ~ fibers is comparable to that of air gap spun. Wet spinning die 5 1 swell through a 60 spinnerette was measured under the following conditions:
7~ cellulose ~IV = 2~5) DMEAO/NMMO: 3:1 ¦ Solution and bath temperature: 75C
0 ¦ Spinbath: Water Ext~usion velocity: 1.1 meters/min.
The tensile properties presented in Table I, below, show that freeze drying only slightly reduces the tensile properties. ~he fibers as spun exhibit a tremendously swollen macrostructure. Primary swelling values of greater than ;00~ (~ g water/gram cellulose) were obtained. Primary swelling values _an be as high as 1000% depending on spinnlng condi ions. I- ~hese ~highly swollen fibers are freeze dried, the highly porous 1 structure can be seen b~v a scanning electron microscope (sem).
0 I- ~he ~ibers are air dried, the swollen macrostructu-e Il _ 1 9-~1 i . `5 ~
. I , ~collapses, resulting in a compacted fiber with a secondary ,lswe1ling value of less than 100~

TABLE I
lTensile Properties of Air Dried and Freeze Drled iWet Spun Cellulose Fibers I Tenacity Elong. (~) Modulus at 5~ ¦
(g/den) (g/den) Sam~le Denier Cond. Wet Cond. Wet Cond. We~
I _ ___ .
1.6 Draw Ratio 1.5 2.20 0.95 6 7 30 14 Air Dried 1.6 Draw Ratio 1.5 2.00 0.85 8 9 30 12 ~Freeze Dried ¦The physical properties presented in Table I are typical of wet ¦spun cellulose fibers which may be spun using a N~ O/DME~O
i solvent system.

Since the fibers are highly swollen as spun, several interes'ing properties result: I
(1) When the fibers are allowed to air dry, the fibers ¦
tend ~o stick together and are very hard to separate. This may be of some advantage for non-woven products.
(2) The fibers have a high propensity to fibrillate.
In applications where high coverage is desired, this fiber .~ay be ~-ll suited.
l (3) Due to the open cellulose mat.ix, fibers or fil~s ; may be used as a substrate or a host of tillers ~e.g., i! herblcides, ?er-~lmes or used without ~illers for filtration ~applic~tions).
l Although our invention has been described above and I a?pended by Examples below in terms of selected 2refer~ed i embodiments, it should not ~e limited thereto, since other equivalent embodiments and modifications and improvements thereto wlll readily occur to one skilled in the art. It is, the efore, understood that the appended claims following the Examples cover all such equivalent embodiments and modifications and improv-ements as fall within the spirit and scope of the inventlon.

N,N-dimethylethanolamine N-oxide (DM~O) containing 8~ ¦
w/w of water and N-methylmorpholine N-oxide (NMMO) containing 16% w/w of water were mixed so as to obtain a mixture where the weight ratio of N,N-dimethylethanolamine N-oxide to N-methyl-morpholine N-oxide was 3 to 1. The total water content was 10 w/w. Both starting amine oxides in their state of hydration were solid at room temperature. After mixing, the temperacure was raised to 80C in orde- to melt the solid mixture. The liquid 0 mixture was then cooled to room temperature where it remained liquid for at least 24 hours.
Cellulose (dissolving grade wood pulp fibers) was added at 8% w/w to the liquid amine oxides mixture at room temperature.
l Propylgallate (0.01% w/w) was added to prevent cellulose l' degradation. After mixing for 2 hours at room temperature, the ! cellulose fibers were swollen but did not dissolve. Then the temperature was raised to 70~C where dissolution of the cellulose I
fibers occurred readily and a homogeneous solution was obtained.

I The com~osition of .~e solution was: 8.0% w/w cellulose, 83.3~

~ -21-5~

w~w amine oxides (62.5~ w~w N,N-dimethylethanolamine N-oxide ¦~DME~O) and 20.8% w/w N-methylmorpholine N-oxide) (NMMO) and 9.3 water. The cellulose solution was cooled to room temperature.
The solution viscosity inc-eased appreciably. The solution ; remained homogeneous for at least five days, thereafter becoming cloudy. A cellulose precipitate in the form of spherulites was obtained. ~pon reheating above 45C, the cellulose precipitate ¦redissolved and a homogeneous solution was obtained once more.
l After cooling to room temperature, the solution remained stable ) ¦ for several days.

~n amine oxide mixture was prepared as in Example 1.
¦Water was then added to the liquid mixture to raise its water content from 10% to 25% w/wO Cellulose was added at 6% w/w to ; the liquid mixture. Propylgallate (0.01% w/w) was also added.
¦After two hours of mixing, the fibrous cellulose remained with no ¦
appearance of swelling. The temperature was then raised to 70C
and after two hours, no changes were observed. water was .hen ¦removed at 70C under reduced pressure. As the water removal 3 proceeded, the fibrous cellulose went through a highly swollen state and finally dissolved to produce a homogeneous cellulose solution. Analysis of the solution at this point gave 6.9~ w/w cellulose, 81.;% w/w amine oxides (61.1~ w/w N,N dimethyl ¦ethanolamine N-oxide (DMEAO) and 20.4~ w/w N-methylmor?holine N-oxide (~LMMO) ) and 11.6% w/w water. The solution could then ~e I cooled to room temperature where it remained liquid for at least five days, thereafter becoming cloudy as cellulose ?recipitated.

11 :

? ~ ~3 ~

N-methylmor?holine ~-oxide (NMMO) conta~ning 12% w/w of l water and N,N-dimethylcyclohexylamine (DMCAO) N-oxide contaiains i 14% w/w of water were mixed so as to obtain a mixture where the ; ~ weight ratio of the two amine oxides was 1:1. The t~tal water content was 13%. Both amine oxides were solid at room tempera-ture; The solid mixture was melted at 80C and, upon cooling to room temperature, it remained liquid for at least 2~ hours.
Cellulose was added at 8% w/w to the liquid mixture.
Propylgallate (0.01% w/w) was also added. After two hours, the fi~rous cellulose remained only swollen. Then the temperature was raised to 70C where dissolution occurred readily and a homogeneous solution was obtained. The composite of the solution was 8.0~ w/w cellulose, 80.0% w/w amine oxides (40.0% w/w N-methylmorpholine N-oxide (~MMO) and 40.0% w/w N,N-dimethyl- !
cyclohexylamine N-oxide) (DMCAO) and 12.0~ w/w water. The solution could then be cooled to room te~perature where it remained liquid for at least five days, thereafter becoming cloudy as cellulose precipitated.

N,N-dimethylethanolamine N-oxide (DMEAO) containing 8 w/w of water and N,N-dimethylcyclohexylamine N-oxide (DMCAO) containing 14~ w/w of water were mixed so as to obtain a mixture where the weight ratio of the two amine oxides was 1:1. The ¦total wa~er content was 11% w/w. Both amine oxides ~ere solid at i room temperature. The solid mixture was melted a- 30C and u?on l cooling to room temperature, it remained liquid for at leas' 2 I hours.
~ Cellulose was added at 8~ w/w to the liquid mixlu-e.
;0 l ?ropylgallate (0.01~ w/~) was also added. Alter two hours, _he 1, 'i, ,1 -23~ ~

A-~

Il fi~rous cellulose remal.~ed only swollen. Then the temperature -,I was -~ised to 70'C where ~issolution occurred readily and a homogeneous solution was obtained. The composition of the ¦soiution was 8.0~ w/w cellulose, 81.8~ w~w amlne oxides !10.9%

ll w/w ~,N-dimethylethanolamine N-oxide and ao.g~ w/w ~,N-dimethyl- I
I cyclohexylamine N-oxide) and 10.2% w/w water. The solution could I

then be cooled to room temperature where it remained liquid for at least five days, thereafter becoming cloudy as cellulose l precipitated.

A ~ertiary amine ~-oxldes mixture was prepared as in ,. ~p,~ e Example 1. ~ a~ (O.O1% w/w) was also added to the liquid mixture. Cellulose and the liquid amine oxides mixture were fed simul~aneously into a twin-screw extruder. Cellulose concentration was 8~ w/w. The first zone of the extruder was maintained at room temperature where mixing of the compounds took ¦
place and swelling of the fibrous cellulose o-curred. The second zone was heated to 90C and maintained under reduced pressure in ~ order to obtain dissolution of the cellulose and de2eration of 0 the solution. An deaerated homogeneous cellulose solution emerged at the end of the extruder. The solution could then be used in the production of shaped cellulosic artlcles by precipitation of the cellulose in a bath containing a non-solvent such as water.

,_ ~ EXAMPLE 6 ., The solution in Example ~ was metered ou~ of the extruder through a slit 200 microns in thic~ness. The slit was immersed in a water bath at 40C. The _esul~ing cellulosic membrane was washed free of amine oxides by successive ilT.~ersion ~ ll ~ -24-l ll ~ 5~

Il in wa~e-. rrhe as-spun membrane had a primary swelling of 5 g ,~water~l g ~ellulose. The swelling was measured after cent-ifu~a-ion at 1000 G for 30 minutes. The membrane was then soaked ~n lan aqueous solution containing 25~ glycerlne and then dried at S room temperature for 24 hours. The composition of the memDrane after dryinq was 22% w/w cellulose, 61% w/w glycerine and 17% w/'w water. The membrane displayed a very porous structure.

Comparison of three mixtures: Mixtures of N~MO/DME~O, !0 NMMO/DMCAO, CMEAO-DMCAO were prepared with various water con-'ents. The phase diagram of the mixtures was determined at room temperature (~J23C) and the solubility of cellulose in these mixtures was measured. 3ifferent solution preparations f~om these mixtures were also studied.
Figure 1 shows the phase diagram of ~MMO/DMEAO mixture at room temperature. Addition of DMEAO ,o NMMO decreases the water con~ent for which the solvent is liquid at room tempera-ture. A mixture of NMMO/DMEAO 30:70 weight ra'io produces the lowest water content (~J7.5%) when the mixture remains liauid at room temperature. Figure 2 gives the maximum water concentration for a 10 and 20% cellulose solution in N~MO/DMEAO mix~ures. It can be shown from these figures that a 10~ cellulose solution is obtained without any water removed for mixture of ~O/DMEAO with I
weight ratio in the neighborhood of 30:70. Similarly, solutions 1 or 10~ cellulose and more can be achieved in DMEAO/N~MO mixtures ~y removing far less water than required with N~MO al3ne. Table l II gives the ~ water necessary to remove f3r different liquid ¦¦solvents to achieve a 20~ cellulose solution. Compared to N~O, llwhere ~0~ water has to be ~emoved, less ~han 9~ wa~er, and as low 1~ .
Il -25- I

!

i as 3~, needs to be removed ~ith amine oxide mixtures. Anothe-as?ect of these li~uid mlxtures is their ability to form ?asty slur-ies at room ,emperature where the liquid cannot be pressed out.
; ¦ After swelling of the cellulose, increasing temperature and applying vacuum, if necessary, result in rapid dissolution.
Temperatures as low as 80C can be used to make solutions. NMMO
and DMEAO mixtuFés can also be recovered simultaneously by water 1 evaporation. Once the solution is achieved, it remains in a 0 ¦"liquid" state, even at room temperature. Removing of more ~ater from the solution will finally cause it to crystallize.
Solutions with NMMO alone will always crystallize at any water content.

TABLE II
l; ~ Water Removed ~rom Liquid Solvents To Obtain a 20% Cellulose Solution H2O at Room% H2O in Temperature Solvent (r~23C) for for 20~ ~ ~2 Solvent Li~ui SolventCellulose Removed NMMO/DMEAO 50:50 12 3 9 NMMO/DMEAO 30:70 7.5 3.5 4 NMMO/DMCAO 50:50 14 11 3 D~EAO/DMCAO 50:50 11 3 8 I 1, NMMO: N-methylmor~holine N-oxide DMEAO: N,N-dimethylethanolamine N-oxide DMCAO: N,N-dimethylcyclohexvlamine N-oxide .1 ' ~ ,c '` ~ ~3 ~ ~ ~

This is an expansion of Example 1 above. This example describes mainly the behavior of cellulose with DMAEO/NMMO
solvent mixtures liquid at room temperature.

A. Cellulose Samples Cellulose samples of various molecular weight were utilized. Acid hydrolysis (boiling 2N HCl for 30 minutes) of regular rayon and commercial dissolving wood pulp (V-68 from Buckeye Cellulose, Memphis, Tennessee) produce low molecular weight cellulose samples. Buckeye V-68 and V-60 pumps were also used. Buckeye V-68 pulp was modified by further bleaching in order to reduce the molecular weight. The cellulose samples used througho~t this work had the following cuene intrinsic viscosity (~) (Table III). V 68 and V-60 are trademarks of Buckeye Cellulose.

TABLE III

Cuene Intrinsic Viscosity (~) and DP* of Cellulose Sampl s No. Sample (~ DP
1 Hydrolyzed rayon 0.2 20 2 Hydrolyzed wood pulp 1.1 180 3 Buckeye Modified V-68 2.0 390 4 Buckeye V-68 2.9 600 Buckeye V-60 3.5 800 * "Cellulose and Cellulose Derivatives--Part IV", edited by N. M
Bikales and L. Segal, Wiley - Interscience at 484 (1971).

i 3~ Solvent Pre a~ation Mixtures of DME~O, NMM0 and water were pre~ared.
DME~O~ O weight ra io of 3 and water con~ent of 12~ (w/w) ~as ~the prefer.Qd composition. Water content was determined by ~arl ischer titration and by an aqua-tester of C. W. Brabender ~ Co., ¦~ackensack, New Jersey, based on the reaction of water with calcium carbide to produce acetylene. ~mine oxides were analyzed by both titration with an acid (see A. S. Basov et al., NEFTEPERERAB. NE~TEKHIM 1 at 60-61 (1979)) and reaction with 0 SO~ (see C. ~. Mitchel et al., ANAL. BIOCHEM. 28 at 261-268 (1g69). It should be noted that water determination with Karl Fischer titration and Brabender aqua-tester were in good agreement when using NMMO alone. With DMEAO or mixture of DMEA0/NMMO, water content by Karl Fischer titration always gave values greater than the aqua tester. This difference is believed to arise from a decomposition product of DMEAO. ~mine oxides are known to thermally decompose. DMEAO will undergo a Cope .earrangement (3-elimination) to produce acetaldehyde. Aldehydes will interfere with the Rarl Fischer reagent. NMMO does not 0 decompose via a ~-elimination with production of aldehyde.

C. Solution Preparation Typically, known amounts of cellulose were added to the mixture of ~MEAO/NMMO/water to produce concen~ration of cellulose ranging from 1 to 15~ w/w. Propylgallate (0.01~ w/w based on solution) was added to prevent polymer degradation. The I
cellulose-solvent mixtures were kept 24 hours at room ¦temperature. If necessary, temperature was then lncreased ~o obt~in dissolution of cellulose. A maximum temperature _ 110 I was used. A~ter dissolution of cellulose (-~hen it occur~ed), 'he ,0 sol~1tions were cooled to room temperature and observed ~or up ~o 2 months. ~olution composition was determined bv t:~e methods -2~-Idesc~i~ed earlier plus ~ravimetric ~etermination of cellulose after ?recl~itation and ext~action of the solvent wi.~ methanol.
~ When phase separation occurred, the solutlons were ¦¦cen~ri~uged at an average relative centrifugal force of 20,000.
Precaution was taken to prevent heating of the solutlon.

D. Optical Microscopy Solutions were examined with Zeiss Universal, Oberkochen, West Germany, polariziny microscope equipped with a Mettler (~ighpstown,, New Jersey) ~P52, hot stage. ~hen 0 birefrinsent structures were obtained, the sign of the birefringence was measured by fitting the microscope with a quartz plate.

E. X-Ray Analysis X-ray diffractograms were obtained using CuK
radiation and Philips (Mahwah, New Jersey) diffractometer.

F. DSC Measuremen.
D~C measurements were pe~formed with a Perkin-Elmer (Norwalk, Connecticut) ~SC II.

G. Procedure and Discussion 0 When cellulose was added to the solvent (DM~AO/
NMMO; 3/1 and 12% H20) at ~oom ~emperature, onlv swelling was I observed and no homogeneous solution obtalned. A sample of V-S3 l pulp was also ball-milled for 48 hours to produce an amorphous ! cellulose. ~ven then, no dissolution occ r-ed thus eli.minating the ?ossibility that crystallinity and/or ilber morphology hampered dissolution at room temperature. It is ~ossible that a f-aclion of the cellulosic material dissolves at room _em?era-1~ 1 ¦ ~ure, bu~ even at 1~ cellulose concentration, many undiss~lved, ¦hiahly swollen materials can be seen under the microsco~e and the na~ed eve as t;~e solution appears cloudy.
In most cases, heating the cellulose-solven' mix_ures causes the cellulose to dissolve and clear homogeneous solutlons are obtained. Generally, a temperature of 80C is sufficient to obtain dissolution. The higher the cellulose concentration and/or the higher the molecular weight, the longer it would take to get complete dissolution. Increasing solution viscosity 0 afrec.ing diffusion rate is likely responsible and stirring in this case will help. Higher temperature (e.g., 110C) also decreases viscosity, thus increasing dissolution time. Homo-¦geneous solutions were obtained with 10% cellulose or less.
¦Above 10% cellulose, complete dissolution was never achieved even with the very low molecular weight~ In these cases, it was necessary to reduce the water content of the solvent mixture (<12~) in order to get dissolution. With much less than 12~
¦water, the DMEAO/N~O (3/1) mixture is no longer liquid at room temperature. Since we were interested in studying the behavior ~o of amine oxide-cellulose solutions at room temperature, mainly solutions of 1 to 10% cellulose were wor~ed with, for which the solvent ~ixture could be liquid at room temperature.
Upon cooling to room temperature, solution's vi,cosi_y considerably increases. As expected, solutions of low molecular weight cellulose and/or low cellulose concen.ration will have t.he lowest viscosities and will maintain flow1ns characteristics.
Other solutions display a hard rubbery state but will start flowing when reheated.
l After standing at room temperature for several hours to 30 ~ several days, some solutions became increasingly opaque.
l ll l _30-ll ~c~ 3~

I ~xamination of the solutions under an optical microscooe reveals l¦small bi~efringent whis~ers. These whiskers then develop to spherulites witnin 48 hours. These spherulites display a maltese l~cr3ss between c-ossed nicols. Solutions of 5% cellulose or less ¦ did not produce a two-phase system within two (2) months for cellulose with a cuene intrinsic viscosity ranging from 0 2 to 3.;. On the other hand, solutions of 7% cellulose or more did give a "precipitate" in the form of spherulitic ~articles suspended in a liquid phase. The induction period as observed 0 visually (naked eye and low magnification (300x) optical microscope) ranges from 2 to 7 days corresponding to cellulose concentration of 10 and 7~, respectively. This induction period appears independent of cellulose molecular weight, at least for the range investigated in this wor~ (~ (cuene) of 0.2 to 3.5.
¦Within two days after beginning of growth, the spherulites appea~
¦to have reached their final dimension. The size of the ¦spherulites varies mainly with cellulose concentration, indeoendently of molecular weightO Under mag~ification, we saw spherulites obtained from 7 and 10% cellulose ([~ = 1.1) solutions. The spherulites had an average diameter of 60 and 2S
~m for the 7 and 10% solutions, respectively.
The solutions that give a ~precipitate~l and that are still flowing can be centrifuged and a sediment obtained. The supernatant liquid and sediment are separated and anal~zed for cellulose content. For a 7~ cellulose ([~ = 1.1) solution, centrifugation of the opaque solution at 20,000 relative centrifugal force gives a clear supernatant liquid of ~
¦cellulose composition and a pasty-like sediment of 9~ cellulose l composition. The solvent composition is the same in ~oth ?hases.
The spherulite's st~ucture is not altered bv the cent-i~ugation ' -31-_cocess. ~eating of the s~herulite's suspension resulLs in the ¦?rogressive loss of birefrinsence starting at ~35C. Shortly I after~ the spherulites can no longer be seen and a homogeneous , solution is ob~lned. ~fter cooling the solution .o room _ I temperature, s~herulites will reappear after apDroxlmately the ¦same initial induction period. Figure 4 shows the DSC results of a 7~ cellulose ([~] = 1.1) solution. The spherulites suspension (as obtained) displays a broad endotherm (Figure A) with the ¦onset at ~35C. The centrifuged spherulites (9% cellulose) have O ¦ a similar er.dotherm (~igure B) except for the broader peak and higher heat (505 cal/g versus 4.5 ca/g). When the solvent mixture is allowed to crystallize by lowering the water content (for example, 9% H20)l it shows a much narrower endotherm (Figure C) with the onset at ~40C and heat of 2.5 ca/g.
The centrifuged sp~erulites show a broad peak by r~XR
(Figure A), whereas the crystallized solvent mixtures display several x~-ray diffracting peaks (Figure C). Removal of the solvent by washing with water does not af~ect the spherulite's structure. The birefringence remains the same. Drying of the O material after washing results in a typical cellulose II x-ray dif~ractogram (Figure B). It should be noted that addition of water to the clear cellulose solutions will precipitate the cellulose and will give a cellulose II pattern after drying.
However, no spherulites morphology is obtained from this rapid ,, precipitation.
All these results indicate that the spheruli~es obtained in this wor~ are cellulosic in nature. They arise from .he preci~itation of a metastable cellulose solution. The l spheruli,es are highly swollen by the liquid solvent and no sign of crystalline order is detectable. Once the liquid solvent is l ., ,j washedr ;he cellulosic chain ~ggregates can form ~nto a li¦ c_ystalline .egister. In cont~as~ to the previous work or Chanzy et al. ('d. Chanzy et al., J. ?OLYMER SC;. (Pol~m. Let. Ed.) 17 z~
~ 219-226 (1979)), where c.vs~allization of the solvent produced 1 he spherulitic morphology, the solvent in our wor~ does not crystallize. The positive birefringence sign of our sphorulites (before and after washing with water) indicates a radial chain alignment of the celluloslc polymer. Chanzy et al. above also obtained positive birerringence of the spherulites but only after ¦
0 ¦ removal of the crystallized solvent. The spherulites obtained by Chanzy also displayed a banded structure that disappeared upon removal of the solvent. In our case, a banded structure was never observed.
¦ Gonoboblev reported formation of spherulites ~rom ¦ cellulose solutions in triethylamine N-oxide (TEAO)/dimethylfor-¦mamide (DMF). See L. N. Gonoboblev et al., ZHURNAL PRIKLODI~OI
¦K~IMII 53(10) at 2309-2313 (1980). Under polarized light, the ¦spherulites had a banded Maltese cross structure. They could ¦also be centrifuged and the sediment presented an enrichmen' i~
0 ¦celluloseO The spherulites had a crystalline structure as seen ¦by the narrow rings of the x-ray diffraction patterns. The diffraction pattern corresponded to none of the known cellulose crystalline polymorphs and it was concluded that the crystallites within the spherulites consisted of solvated macromolecules of ¦ cellulose. ~owever, no mention was made of the sign of ~birefringence of the spherulites and of the changes occurring ¦lu?on removal of the solvent .~ixture.
Spherulitic crystallization of cellulose has been jlprevlously reported by ~hilipp and cowor~ers, who used dilute ,0 lsolutions or cellulose (0.002% to 0.1%) in dimethylsui~oxide and ll .,, ~¦ ~ethylamlne. ~. Phili?p et al., FASER FORSC~. T~XTIL. T~C.1. 26 ~at 89-~0 ~1975). ~recloitation occurred when the metnylamine evaporated. The s?herulites were banded but no comments concerning their bi erringence were reported. The authors also ; indicated that well-Lormed spherulites could not be produced a.
cellulose concentrations higher than 0.064%. Takai et al.
observed large two-dimensional spherulites in the pelllcle o_ bacterial cellulose formed in static cultures of Acetobacter Xylinum. See M. Takai et al., CELLULOSE C~E~. AND TEC~. 15 at 0 153-170 (1981).
We feel the above demonstrate that spherulites of cellulose are obtained from a metastable cellulose solution in amine oxide solvent mixture. The cellulose chains ado~t a radial arrangement in the spherulites. The highly swollen cellulose structure displays very poor crystalline organization. No crystallized solvent is detected. ~emoval of the liquid solvQnt ¦and drying cause the cellulose to crystallize in a cellulose II
formO The growth's induction period and size or the spherulites are co rolled by the cellulo-e concentration.

l -34- 1l

Claims (43)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. A substantially homogeneous extrudable solution of base material, comprising:
(a) a predetermined amount of each of two or more tertiary amine oxides, each of which is in a known state of water hydration and each having a known melting point, to form an initial liquid mixture, the tertiary amine oxides selected from the group consisting of N,N,N-triethylamine N-oxide; N,N-dimethyl -cyclohexylamine N-oxide; N-methylmorpholine N-oxide; N-methyl-piperidine N-oxide; N-methylhexamethyleneimine N-oxide; N-N-di-methylbenzylamine N-oxide; and N,N-dimethylethanolamine N-oxide, said amount of each sufficient to depress the melting point of the initial mixture below the melting point of each of said tertiary amine oxides in their known state of hydration and to form said liquid;
(b) a predetermined amount of a base material added to said initial liquid mixture, the base material selected from the group consisting of suitable water soluble polymers, nylon, cellulose, and other polysaccharides; and (c) water, including but not necessarily limited to the hydrated water above;
whereby the amount of initial mixture of tertiary amine oxides (a) is sufficient to dissolve the base material and to form a sub-stantially homogeneous extrudable solution, and the amount of water (c) is just sufficient to provide the dissolved base mate-rial with a predetermined melting point.

2. The extrudable solution of Claim 1, wherein the base material is cellulose.

3. The extrudable solution of Claim 2, wherein the tertiary amine oxides forming the initial mixture comprise N-methylmorpho-line N-oxide and N,N-dimethylethanolamine N-oxide, wherein the weight fraction of N-methylmorpholine N-oxide to N,N-dimethyl-ethanol amine N-oxide is from about 0.15 to about 0.5.

4. The extrudable solution of Claim 3, wherein the cellu-lose is from about 5% to about 20% by weight or said solution, and the total amount of water is from about 5% to about 10% by weight of said solution.

5. The extrudable solution of Claim 2, wherein the tertiary amine oxides forming the initial mixture comprises N-methylmor-pholine N-oxide and N,N-dimethylcyclohexylamine N-oxide, wherein the weight fraction of N-methylmorpholine to N,N-dimethylcyclo-hexylamine is from about 0.3 to about 0.7.

6. The extrudable solution of Claim 5, wherein the cellulose is from about 5% to about 20% by weight of said solution, and the total amount of water is from about 10% to about 15% of said solution.

7. The extrudable solution of Claim 2, wherein the tertiary amine oxides forming the initial mixture comprises N,N-dimethyl-cyclohexylamine oxide and N,N-dimethylethanolamine N-oxide, wherein the weight fraction of N,N-dimethylcyclohexylamine to N,N-dimethylethanolamine N-oxide is from about 0.15 to about 0.50.

8. The extrudable solution of Claim 3, wherein the cellu-lose is from about 5% to about 20% by weight of said solution, and the total amount of water is from about 5% to about 10% by weight of said solution.

9. Process for manufacture of a substantially homogeneous extrudable solution of a base material having a predetermined melting point, comprising:
(a) mixing a predetermined amount of each of two or more constituent tertiary amine oxides, each of which is in a known state of hydration and each having a known melting point, to form an initial mixture, the tertiary amine oxides selected from the group consisting of N,N,N-triethylamine N-oxide; N,N-dimethyl-cyclohexylamine N-oxide; N-methylmorpholine N-oxide; N-methyl-piperidine N-oxide; N-methylhexamethyleneimine N-oxide; N,N-di-methylbenzylamine N-oxide; and N,N-dimethylethanolamine N-oxide, said constituent amounts of amine oxides sufficient to depress the melting point of the initial mixture below the melting points of each of said tertiary amine oxides in their known state of hydration, and to form a liquid;
(b) water, inclusive of the water of hydration of said tertiary amine oxides, sufficient to bring the water content of the initial mixture (d) to a predetermined amount;
(c) adding and mixing a predetermined amount of a base material selected from the group consisting of suitable polymers, nylon, cellulose, and other polysaccharides with said initial aqueous mixture of tertiary amine oxides to form a slurry; and (d) mixing the slurry until a substantially homogeneous extrudable solution of the base material having a predetermined melting point is achieved.

10. The process of Claim 9, wherein the base material is cellulose.

11. The process of Claim 10, wherein the amount of water of the initial mixture (a) is less than 15% by weight, further comprising adjusting water in the initial mixture to a sufficient degree to provide the initial mixture with a predetermined water content, but still less than about 15%.

12. The process of claim 11, further comprising:
adding the aqueous solvent initial mixture to said base cellulose material at a temperature from about 20°C to about 60°C
to form a slurry; and heating and mixing said slurry until said slurry is above about 70°C until a substantially homogeneous extrudable solution of the cellulose material is achieved.

13. The process of Claim 10, wherein the amount of water of the initial mixture (a) is greater than 15%; further comprising:
(a) heating and mixing said slurry until said slurry is above about 70°C; and (b) removing sufficient water until a substantially homogeneous extrudable solution of the cellulose material is achieved.

14. The process of Claim 10, wherein the amount of water of the initial mixture is less than about 15%, further comprising:
(a) heating up said initial mixture (a) from a tempera-ture of about 20°C to about 60°C until the initial temperature of said initial mixture (a) is greater than 70°C; then (b) adding and mixing a predetermined amount of cellulose until a substantially homogeneous extrudable cellulose solution is achieved.

15. The process of Claim 11, wherein the tertiary amine oxides selected are N-methylmorpholine N-oxide and N,N-dimethyl-ethanolamine N-oxide, wherein the N-methylmorpholine N-oxide present in a weight fraction of about 0.15 to about 0.5.

16. The process of Claim 15, wherein the ratio of N-methyl-morpholine N-oxide to N,N-dimethylethanolamine is about 1:3, respectively and the amount of water present in the initial mixture is about 12% by weight.

17. The process of Claim 11, wherein the tertiary amine oxides selected are N-methylmorpholine N-oxide and N,N-dimethyl cyclohexylamine N-oxide, the N-methylmorpholine N-oxide present in a weight fraction of about 0.3 to about 0.7, respectively.

18. The process of Claim 17, wherein the ratio of N-methyl-morpholine N-oxide to N,N-dimethylcyclohexylamine N-oxide is about 1:1, and the amount of water present in the initial mixture is about 14% by weight.

19. The process of Claim 11, wherein the tertiary amine oxides selected are N,N-dimethylcyclohexylamine N-oxide and N,N-dimethylethanolamine N-oxide, the N,N-dimethylcyclohexylamine N-oxide present in a weight fraction of about 0.15 to about 0.5.

20. The process of Claim 19, wherein the weight ratio of N,N-dimethylcyclohexylamine N-oxide to N,N-dimethylethanolamine N-oxide is about 1:3 by weight, respectively, and the amount of water present in the initial mixture is about 12% by weight

21. The process of claim 12, 13 or 14, further comprising:
cooling gradually the homogeneous extrudable solution below about 70°C to provide a metastable aqueous cellulose solution capable of extrusion.

22. A process for extruding a solution of cellulosic material in a solvent comprising two or more suitable tertiary amine oxides, comprising:
(a) dissolving in a predetermined amount of water a cellulosic base material selected from the group consisting of cellulose, cellulose and any other polysaccharide, cellulose and any other water soluble polymer, and cellulose and nylon, in a solvent mixture comprising two or more suitable tertiary amine oxides selected from the group consisting of N,N,N-triethylamine N-oxide; N,N-dimethylcyclohexylamine N-oxide; N-methylmorpholine N-oxide; N-methylpiperidine N-oxide; N,N-methylhexamethvyleneimine N-oxide; N,N-dimethylbenzylamine N-oxide; N,N-dimethylethanolamine N-oxide, to form a substantially homogeneous extrudable solution of said cellulosic basic material; and (b) extruding said substantially homogeneous solution from about 20°C to about 60°C directly into one or more sequential precipitation bath(s), each of which comprises a non-solvent to said cellulosic basic material, for a sufficient time to remove substantially all the tertiary amine oxides from said cellulosic basic material.

23. The process of Claim 22, in which the cellulosic basic material comprises cellulose.

24. The process of Claim 23, in which the non-solvent is water, and the bath is maintained from about 20°C to about 30°C.

25. The process of Claim 22, in which the non-solvent is selected from the group consisting of methanol, ethanol, propanol, isopropanol, and n-butanol.

26. The process of Claim 23, in which the solvent mixture comprises N-methylmorpholine N-oxide and N,N-dimethylethanolamine N-oxide, wherein the N-methylmorpholine N-oxide is present in a weight fraction of about 0.15 to about 0.5.

27. The process of Claim 26, in which the ratio of N-methyl morpholine N-oxide to N,N-dimethylethanolamine is about 1:3 respectively, and the amount of water present in the cellulosic base material immediately before extrusion is from about 10% to about 13% by weight.

28. The process of Claim 23, in which tne solvent mixture comprises N-methylmorpholine N-oxide and N,N-dimethylcyclohexyl-amine N-oxide, wherein the N-methylmorpholine is present in a weight fraction or about 0.3 to about 0.7, respectively.

29. The process of Claim 28, in which the ratio of N-methyl-morpholine N-oxide to N,N-dimethylcyclohexylamine N-oxide is about 1:1, and the amount of water present in the cellulosic base material immediately before extrusion is from about 11% to about 13% by weight.

30. The process or Claim 23, in which the solvent mixture comprises N,N-dimethylcyclohexylamine N-oxide and N,N-dimethyl-ethanolamine N-oxide, wherein the fraction of N-dimethylethanol-amine is about 0.5.

31. The process of Claim 30, in which the weight ratio of N,N-dimethylcyclohexylamine N-oxide to N,N-dimethylethanolamine N-oxide is about 1:3, respectively, and the amount of water present in the cellulosic base material immediately before extrusion is about 12% by weight.

32. A dried cellulosic base material product manufactured by a process of direct wet extrusion, said process comprising:
(a) dissolving in a predetermined amount of water a cellulosic basic material selected from the group consisting of cellulose, cellulose and any other polysaccharide and cellulose and nylon, in a solvent mixture comprising two or more suitable tertiary amine oxides selected from the group consisting of N,N,N-triethylamine N-oxide; N,N-dimethylcyclohexylamine N-oxide;
N-methylmorpholine N-oxide; N-metnylpiperidine N-oxide; N-methyl-hexamethyleneimine N-oxide; N,N-dimethylbenzylamine N-oxide; and N,N-dimethylethanolamine N-oxide to form a substantially homo-geneous extrudable solution of said cellulosic basic material;
(b) extruding said substantially homogeneous solution from about 20°C to about 60°C directly into one or more sequential precipitation baths, each of which comprises a non-solvent to said cellulosic basic material for a sufficient time to remove substantially all the tertiary amine oxides from said cellulosic base material to form a wet swollen cellulosic extrudate having pores which entrap water;
(c) drying said wet swollen cellulosic extrudate to form a dried cellulosic base material product.

33. The dried cellulosic product of claim 32 manufactured by a process of direct wet extrusion, said process further comprising the step of:
immersing the wet swollen cellulosic extrudate prior to drying in a second non-solvent bath, comprising one of the group consisting of a non-volatile compound dissolved in a vola-tile liquid, whereby the liquid is capable of being exchanged for said entrapped water in the pores of the wet swollen cellulosic extrudate, and whereby after evaporation of the volatile liquid, substantially only the non-volatile compound remains.

34. The dried cellulosic product of Claim 33, manufactured by a process of direct wet extrusion, whereby the second non-solvent bath comprises glycerine and water.

35. The dried cellulosic product of claim 33, manufactured by a process of direct wet extrusion, wherein the weight ratio of glycerine to water is about 1:3.

36. The dried cellulosic product of Claim 32, manufactured by a process of direct wet extrusion, said process further comprising the step of:
freeze drying the wet swollen cellulose extrudate to remove the entrapped water from the pores while preventing collapse of said pores.

37. The dried cellulosic product of Claim 32, manufactured by a process of direct wet extrusion, said process further comprising the steps of:
(a) immersing the wet swollen cellulosic extrudate prior to drying in a second non-solvent bath, said second non-solvent bath comprising a non-polar volatile solvent, whereby the non-polar volatile solvent is capable of being exchanged for said entrapped water in the pores of the wet swollen cellulosic extrudate, to form a non-polar volatile solvent swollen cellulosic extrudate; and (b) air drying said non-polar volatile solvent swollen cellulosic extrudate to remove the entrapped non-polar volatile solvent from the pores while preventing collapse of said pores.

38. A dried cellulosic base material product of Claim 32 manufactured by a process of direct wet extrusion, wherein the solvent mixture comprises N-methylmorpholine N-oxide and N,N-dimethylethanolamine N-oxide, wherein the N -methylmorpholine N-oxide is present in a weight fraction of about 0.15 to about 0.5.

39. The dried cellulosic base material product of Claim 38 manufactured by a process of direct wet extrusion, wherein the ratio of N-methylmorpholine N-oxide to N,N-dimethylethanolamine is about 1:3 respectively, and the amount of water present in the cellulosic basic material immediately before extrusion is from about 10% to about 13% by weight.

40. The dried cellulosic base material product of Claim 32 manufactured by a process of direct wet extrusion, wherein the solvent mixture comprises N-methylmorpholine N-oxide and N,N-dimethylcyclohexylamine N-oxide, wherein the N-methylmorpholine is present in a weight fraction of about 0.3 to about 0.7, respectively.

41. The dried cellulosic base material product of Claim manufactured by a process of direct wet extrusion, wherein the weight ratio of N-methylmorpholine N-oxide to N,N-dimethylethanol-amine N-oxide is about 1:1, and the amount of water present in the cellulosic basic material immediately before extrusion is from about 11% to about 13% by weight.

42. The dried cellulosic base material product of Claim 32 manufactured by a process of direct wet extrusion, wherein the solvent mixture comprises N,N-dimethylcyclohexylamine N-oxide and N,N-dimethylethanolamine N-oxide, wherein the fraction of N,N-dimethylcyclohexylamine N-oxide is about 0.5.

43. The dried cellulosic base material product of Claim 42 manufactured by a process of direct wet extrusion, whereby the weight ratio of N,N-dimethylcyclohexylamine N-oxide to N,N-dimethylethanolamine N-oxide is about 1:3, respectively, and the amount of water present in the initial mixture is about 12% by weight.