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Патент USA US2404716

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July 23, w46.
v_ l.. HANsLEY
Filed Nov. 4, v1944
' j;
" »gisant
roam/ma raonuc'rs f _
virgin r.. Hensley, Niagara raus, N. Y., assigner
to iE. l. du Pont de Nemours & Company, Wil
mington, Del.,a corporation of Delaware
Application November 4, 1944, Serial No. 562,01€:
V15.7 Claims. (Cl. 26o-_32)
This invention relates to a new composition of
matter and shaped articles produced therefrom.' '
More particularly, this invention relates to an
organic solvent solution of polyacrylonitrile, i. e.
polymerized acrylonitrile or polymerized vinyl
cyanide (CH2=CHCN):, and copolymers and in
terpolymers of acrylonitrile vin which at least
85% by weight of the polymer is acrylonitrile,
and the production of shaped articles from said
organic solvent solution of said polymers of
resulting compositions in such-a manner. Their
extrusion into coagulating baths of the type pro
posed V(including such non-solvents for acrylo
nitrile as water, dilute acid, dilute salt solutions,
etc.) result in the formation of shaped articles
that contain large amounts of the inorganic salt
of the proposed> solvent.
These salts‘are dis
tributed throughout the structure and destroy
the continuity ofthe polyarcylonitrile phase and
the structure possesses poor physical properties.
Removal of these“ salts, when possible, results in
Polyacrylonitrile, and copolymers and inter-
the formation of a porous, spongy, Weak, unde
sirable structure that is very brittle and com
l polymers of acrylonitrile with other polymeriz
able substances, for example vinyl or` acrylic com
pounds in which at least 85% by weight of the
polymer is acrylonitrile have been known for
ment yarn byv extruding, for example the pro
some time and recognized as possessing desirable
posed aqueous sodium sulfocyanide polyacrylo
pletely unsuited for use as a yarn or film. More
over, when it is attempted to form a multîiila
physical and chemical properties including tough
nitrile composition', into a dilute acid bath, it isness and insolubility in and insensitivity to com
found that the individual filaments obtained
mon organic solvents such as methyl or ethyl 20 stick together to form an essentially monoflla
ment structure that is extremely brittle and can
alcohol, acetone, ethyl ether, ethyl acetate, hydro
not be bent or worked without breaking.
carbon solvents, chlorinated hydrocarbons Iand
U. S. Patent No. 2,167,537 to Tobls points out
the like. Because of these facts, numerous at
that certain copolymers of acrylonitrile and an
tempts have been made to form these polymeric
materials into yarns, films and other Vshaped
acid ester (those copolymers containing
v26 _acrylic
not more than 65% of acrylonitrile) are soluble
The copending application of George H.
Latham, Serial No. 562,012, filed of even date .
in' mixtures of organic solvents such 'as dioxan,monochlorbenzene, cyclohexanone, etc, `How-
herewith discloses solutions of polyacrylonitrile Y ever, these liquids are incapable of dissolving or
in dimethyl carbamyl compounds and the pro 30 even swelling polyacrylonitrile or copolymers of
acrylonitrile 'containing higher percentages of
duction of extruded and otherwise shaped articles
acrylonitrile, i. e. acrylonitrile polymers of the
and structures from such solutions. The above
type with which this invention is concerned. As
said application of George H. Latham represents
previously mentioned, polymers containing such
the ñrst successful dissolution of polyacrylo'
nitrile in a solvent to produce a solution which 35 high percentages (at least 85% by weight) of
is suitable for the production'of commercially
useful textile yarns 0r wrapping tissue films, and
acrylonitrile are especially desirable for use be
similar tough, ñexible structures.
cellent chemical . resistance.
The present application relates to a similarly
cause of their good physical properties and ex
It has also been proposed (Rein U. S. Patent
satisfactory dissolution of polyacrylonitrile in an 40 No. 2,117,210) to dissolve polyacrylonitrile in
-molten quatemary -»ammonium salts such as
organic solvent taken from a different class of
organic compounds and the polyacrylonitrile
solutions produced thereby are similarly satis
benzyl pyridinium chloride, an ionizable salt. Al- .
though the resulting solution can allegedly be
factory for the production of tough, flexible,
‘ used to form yarns or films of polyacrylonitrile,
dense, colorless yarns andiilms which are suit
able for vuse in practically all general commercial
the solution itself is dark red to brown in color,
indicating that some decomposition of the poly
acrylonitrile or some reaction between the poly
applications of such products.
acrylonitrile and the molten salt has probably
taken place. Such solutions are not satisfactory
as lithium bromide, zinc chloride and sodium 50 for the production of commercially useful, shaped
articles of polyacrylonitrile. Here again, it has
sulfocyanide will dissolve polyacrylonitrile and it
been found practically impossible to obtain fila
has been proposed (Rein U. ‘5. Patent No.
mentary structures such as yarns from the com
2,140,921) to employ the resulting solutions in the
position. Films or filaments, when obtainable,
formation of yarns and ñlms. However, it has
been found substantially impossible to use the 55 are extremely brittle; they are highly vcolored
It has been known heretofore that concen
trated aqueous solutions of inorganic salts‘such
and very weak, presumably because of the pres
ence within them of residual quaternary am
monium salt. Removal of this salt is difllcult
and the resulting structures contain numerous
the presence within the molecules of strong hy
drogen-bonding forces and in order to dissolve
one of these polymers, it is necessary to 11nd a
material which will undergo hydrogen bonding
and large voids that make the structures sub
stantially useless for commercial purposes.
with the active hydrogen-bonding groups of the
polymer molecules and thus weaken the strong
hydrogen bond within the polymer molecules and
cause the hydrogen-bonding forces to be shared
between molecules of the polymer and the sol
It is therefore an object of this invention to
dissolvel polyacrylonitrile or‘a copolymer or in
terpolymer of acrylonitrile in which at least 85%
by weight oi’ the polymer is acrylonitrile, in a y10 vent. In this mannenit is‘possible to form a
solvent which does not react with or decompose
molecular dispersion of the polymer within the
the polymer and which may be substantially
solvent and thus form a solution.
However, the strength of the hydrogen-bond
completely removed from the structures formed
ing capacity cannot be taken as the sole crite
of such a solution.
It isanother object of this invention to pro
rion as to whether or nota compound will func
duce a solution of polyacrylonitrile or-a copoly
ltion to dissolve an acrylonitrile polymer. It is
mer or interpolymer of acrylonitrile in which at
least 85% by weight of the polymer is acrylo
, also necessary that, in order to function as a
solvent for an'acrylonitrile polymer, the com
pound contain certain groups which will be ca
or decompose the polymer, the solution being 20 pable of satisfactorily sharing a hydrogen bond
suitable for the formation of commercially use
ing force with the particular active group of the
ful, void free articles of polyacrylonitrile, for
acrylonitrile polymer. In most
, these
groups require the presence of a hydrogen atom
example yarns which are suitable as textile yarns
and films which are suitable as wrapping tissue.
on a carbon atom to which the group is'attached
'It is another object of this invention to pro 25 (designated as an alpha-hydrogen atom). Such
groups as require the alpha-hydrogen atom are
duce a solutionvof polyacrylonitrile, or a copoly
ineffective to impart solvent power if the alpha
mer or interpolymer of acrylonitrile in which at
hydrogen atom ls missing. '
least 85% by weight of the polymer is acrylo
It has now been found that groups capable ot
nitrile, in a volatile organic solvent, which so
lution is stable over extended periods of time and 30 conferring solvent power include dimethyl car
and is eminently suited for use in the manufac~
ture of shaped articles such as yarns, films, tubes,
nitrile, in a solvent which does not react with
straws, artiiicial horsehair, bristles and ribbons,
or when highly concentrated, for use in the man
ufacture of molded articles.
It is a still further object of this invention to
produce shaped articles and structures of poly
acrylonitrile, >or copolymers or intel-polymers of
acrylonitrile in which at least 85% by weight of
the polymer is acrylonitrile.
cyano (-CENL thiocyano (-S-CEN) and
It is still another object of this invention to
produce a shaped article or structure of poly
acrylonitrile or copolymers or interpolymers of
acrylonitrile in which at least 85% by Weight of
the polymer is acrylonitrile, for example a yarn,
film, tube, bristle or the like which is tough,
flexible, tenacious and free from voids.
Other objects of the invention will appear
’I‘he objects of the invention may be accom
plished in general by dissolving polyacrylonitrile,
or a copolymer or interpolymer of acrylonitrile
in which at least 85% by weight of the polymer
is acrylonitrile, in an organic compound which
(no „EL lo- l...)
,. rg.
groups, provided however that the cyano, thio
cyano and sulfoxy groups require attachment
50 (through their respective unsatisfied carbon and
sulfur valences) to a carbon atom which is in
turn attached to at least one hydrogen atom
(alpha-hydrogen) in order to render them effec
tive. The dimethyl carbamyl and the form'yl
limido groups are effective in the absence of the
is not a salt and which contains at least _one di 55 alpha-hydrogen atom. (It is possible that they
methyl carbamyl group and at least one cyano
contain the equivalent of an alpha-hydrogen
methylene group. If the solvent has a relatively
atom within their own structures.) lThus, the
low boiling point (less than about 250° C.), the
solution of the acrylonitrile polymer` may then
be formed into a .shaped structure, for example
groups dimethyl carbamyl
CH; o
a yarn or film, and the solvent removed from
the shaped structure to coagulate the same.
When the solvent is relatively non-volatile and
formyl - imido
has a boiling point of about 300° C. or more,
shaped articles may be made from the solution 05 (>CHCN)., thiocyanomethylene (>CHSCN) and
andl at least a portion of the solvent may be re
>CHSOO-, and >CHSOzO-) shall hereinafter
tained therein as a plasticizer for the articles.
be referred to as solvogenic groups and com
It has been recognized in recent years that
pounds containing them are frequently capable
under certain conditions, an atom of hydrogen
is attracted by rather strong forces to two atoms 70 of dissolving an acrylonitrile polymer containing
at least 85% by weight of acrylonitrile.
instead of only one, so that it may be considered
In the event that two or more groups requiring
to be acting as a bond between them. This is
the presence of an alpha-hydrogen atom in order
called the hydrogen bond.
The difficulty of dissolving polymers containing
to render them solvogenic are attached to the
at least 85% by weight of acrylonitrile is due to 75 Same carbon atom and compete with each other
amarre '
for an available alpha-hydrogen atom, the sulf
C Ha .
oxy group, the cyano group and the thiocyano
group take preference over each other in the
order named to form the solvogenic group, the
lower ranking group or groups present assuming
merely'the nature of an inert substituent on the
Gamma-methyl-gammaN N-dimethyl-oarbamyl l
carbon atom.
the ` above-mentioned
It has furthermore been found that compounds
I ì
groups will be solvents for the above-mentioned
polymers only if the carbon content of the com
pound be within certain limits as given below.
If the ratio of carbon to solvogenic groupings
is maintained within the said limits, the com
pounds Will retain solvent properties of the poly
mer leven though the molecule be of considerable
size and complexity. The solvent power of the
compound for acrylonitrile polymers is increased
if additional solvogenic groups are present in the
molecular structure of the compound, the eñîect 20
of these groups being additive.
It has now been found that dimethyl carbamyl
cyanomethylene compounds which are fusible
Without decomposition embraced by the follow
ing formula and preferably having a boiling
point below 250° C. will dissolve polyacrylonitrile,
and copolymers and interpolymers of acrylo
nitrile in which at least 85% by Weight of the
polymer is acrylonitrile:
H2O 0N(C Ha) a
wherein m and q are integers equal to or greater 35
C Ha C N
` than l.; n and p are integers of such value that
n/m is equal to or less than 1.5 and p/q is equal
to or less than 1.5.
These compounds are not salts but may be
cyclic or acyclic in nature and may contain one 40
or more ethylenic or acetylenic linkages. Va
lences other than those contained in the carbon
to-carbon linkages and not shown as satisñed
C HaJJH-èH-C oNmHm
N,N-dimethyl-alpha-cyano-propiona mide
by the above formula must be satisfied by a sub
stituent taken from the group consisting or 45
hydrogen, halogen, oxygen, bivalent sulfur atoms
and hydroxyl, thiol, cyano, thiocyano and sulfoxy
radicals; the total number of halogen, oxygen
and> sulfur atoms and hydroxyl and thiol sub
stituents not exceeding one-half the sum of m-l-q 50
and the number of cyano, thiocyano and sulfoxy
radicals not exceeding the sum of m-i-q. The
respective tolerances of one-half m-i-q and m-l-q
c HaCHQCHfcHCÉC omonm i
N, N»dimethyl~alpha,beta-dicyanocaproamide
for the said two groups of substituents are inde
pendent of each other and members of said 55
groups may be present in the molecule up to their
group tolerances. substituent oxygen and sulfur
atoms may appear in the compound as bivalent
groups either as a side group (carbonyl or thio
carbonyl) or within the` chain (ether or thio 60
ether) as the case may be.
N ,N-dimethyl-alpha-cyano-valeramide
N C-C HzCHnCHsCHqC 0N(CHu) a
g N,N-dimethyl-gamma-cyano-valeramide
C Ha
NC-~CH¢tlJ-C ON(CHa)|
Representative compounds coming Within the
scope of the above formula and suitable for use
as solvents for the above-mentioned acrylonitrile
N ,N-alpha,alpha-tetramethyl-beta-cyanopropionamide
polymers include:
C Hs
C Hs '
N,N»dimethyl-gamma-cyanoisovaleramide .
NG-CHIC omemmn
above room temperature. Shaped structures and
articles can be produced by extruding many of
such solutions into an evaporative or coagulative
medium. By forming the structures in an evap
orative medium, the solvent must be evaporated
therefrom and by forming the structures in a
coagulative medium, the solvent should be re
moved by selective, solution in a non-solvent for
the polymer.
The solutions are prepared by `dissolving the
polyacrylonitrile, or copolymer or interpolymer
fractory in which is embedded an electrical heat
' ing coil I9.
The spinning cell can thus be op
erated at any desired temperature. A plurality
of conduits 2| are provided adjacent thebottomV
of the device vfor passing evaporative medium’
through- the cell so as to evaporate the solvent
from the extruded filaments I5. The.evaporative medium is removed from the cell through
loutlet openings '23.A The yarn comprising the
plurality of filaments I5 is passed from the bottom
of the spinning cell around guide roller 25 and
is wound on a bobbin 21.
of acrylonitrile with one or a mixture of the
’ Referring to Figure 2 of the drawing, the yarn
l5 is removed from the bobbin package 2i and `
above-mentioned solvents. Some of these sol
vents are solid at ordinary temperatures and dis
solve or retain the polymer in clear solution only 15 passed about draw roller 29 and separating roller
3I. From draw roller 29, the yarn is passed to
at elevated temperatures', for example at tem
` peratures of 100° C. or higher, below which tem
' a second draw roller 33 and separating roller 35.
The yarn is passed around the two sets of >draw
rollers including their separating rollers a sum
of the above class, the resulting composition while 20 cient number of turns to prevent slippage of the
yarn. Draw roller 33 is rotated at a greater
hot has the appearance of a true solution. When
speed, for example three to ten times the speed
cooled to room temperature, the composition gen
of draw ‘roller 29. In this manner, the yarn E5
erally takes on the appearance of a gel, which
is stretched between _the two draw rollers. As
gel may, on standing, undergo syneresis. Re
heating of this gel or syneresed mass however 25 the yarn passes between the two draw rollers, a
heating medium is brought into contact with the
causes it to again return to solution form.
yarn through blower nozzles 3i and 39. The
In view `of the relatively high melting points
yarn passing from the draw roller 33 is wound
of some of the solvents of this invention, they
on bobbin 0I. The-drawing or stretching of the
would have comparatively little use in the -pro
duction of a polyacrylonitrile spinning or casting 30 spun yarn as described is not claimed as part
of the present invention, but is claimed in the
solution. Such solvents are, however, excellent
copending application of Daniel T. Meloon, Serial
solvent plasticizers for polyacrylonitrile since
perature the composition resembles a gel. In all
cases when the polymer is dissolved in a solvent
they are soluble in a wide range of proportions
with the said acrylonitrile polymers. The pres
ent invention therefore contemplates solid solu--
tions of acrylonitrile polymers containing at least
85% by weight of acrylonitrile as well as liquid
solutions thereof.
No. 496,397, filed July 28, 1943.
Figure 3 of the drawing illustrates a wet spin
ning apparatus for the production of yarn. The
acrylonitrile polymer solution is passed through
conduit 5I and is extruded through spinneret 53
to form a multiiilament yarn Sli.
The yarn 50
is passed about guide roller 5l which is positioned
Shaped articles obtained from solvent solutions
of pols/acrylonitrile in accordance with the inven 40 within the coagulating liquid in tank 55. The
yarn is then passed about guide roller 5S and is
tion and from which the solvent is subsequently
wound on bobbin 0I.
removed are substantially free of foreign matter
The organic solvent solution of polyacrylonitrile
and voids and substantially undecomposed and
may be cast in the form of a film as illustrated
chemically unchanged from the simple polymer
45 in Figure 4. In accordance with this apparatus,
prior to its solution.
the polymer solution is passed from hopper l!
The above-described organic solvent solutions
on to the endless steel band 'i3 where it is
of acrylonitrile polymer may be shaped in the
smoothed by means of a doctor knife '85. The
form of filaments, yarns, films, tubes and like
band, together with the film, is passed under a
structures by apparatus and processes generally
known in the art, the detailed operating condi 50 means ‘Il for bringing a heated drying medium
tions being suitably modiñed.
Suitable methods and apparatus for the pro
duction of shaped articles of the polymers of this
invention will be readily apparent by reference to
' the following detailed description when taken in 55
connection with the accompanying illustrations
in which:
Figure 1 is a diagrammatic vertical sectional
, view showing a dry spinning cell suitable for use
in accordance with the invention;
Figure 2 is a diagrammatic perspective view
showing a lyarn drawing device for use in con
nection with the invention;
Figure 3 is a diagrammatic perspective view
into contact with the film.
The film 0I is pulled
from the band 'I3 and collected on a mill roll 03.
The polyacrylonitrile for use with the inven
tion is preferably prepared by the ammonium
persulfate catalyzed polymerization of monomeric
acrylonitrile dissolvedor emulsifieddn water. It
can, however, be preparedby any other suitable
type of polymerization reaction such as, for exam
ple, the emulsion type reaction disclosed by U. S.
Patent No. 2,160,054 to Bauer et al. The poly
mer preferably possesses a molecular weight
within- the range of 15,000 to 250,000 or even
higher, .as calculated from viscosity measure
ments by the Staudinger equation:
showing a wet spinning apparatus for use in the 65
Molecular WeightKm0
invention; and
Figure 4 is a diagrammatic side elevational view
showing a suitable film casting apparatus for
use in accordance with the invention.
_viscosity of solution
Referring to Figure 1 of the drawing, reference 70
N” îd'spçclñc vlscoslty- viscosity of solvent 1
numeral I I designates a spinneret through whichv
a plurality of filaments I5 are formed by extrud
C=concentration of the solution expressed as the
ing a ñlament-forming solution supplied to the
number _of moles of the monomer (calculated) per
spinneret by means of conduit I3. The spinning
liter of solution.
cell is jacketed with a material I‘I., such as a re-`
The molecular weight of the polymer obtained
.is dependent on such factors as the concentra.
tion of the monomer in the water, the amount
and type of catalyst present, the temperature of
the reaction, etc. For example, polyacrylcnitrile,
having a molecular weight of approximately
in the coating of wire and electrical parts where
the high chemical and electrical< resistance of the
polymer is important.
For the purpose of definition, a solvent is a
material which, when in the liquid state, is ca
pable of forming solutions in which the polymer
is present in a concentrationl by weight of 5%
In most instances, the polymer is sol
uble in almost all proportions although the mis
60,000 can be prepared as follows: To 94 pounds
of distilled water heated to 40° C. _add 40 grams
of ammonium persulfate-catalyst and 80 grams of
sodium bisulilte activator. Then add 16 pounds -10 cibility may take place at elevated temperatures
of acrylonitrile slowly with stirring over a period
in the case of certaincompounds.
of two hours.v The polyacrylonitrile having the
As also shown, the solvents of the invention
above said molecular weight will precipitate from
are useful not only in connection with polyacryl
the solution. Increasing or decreasing theonitrile, but also with copolymers and inter
amount of the catalyst, while maintaining the
polymers of acrylonitrile and with other poly
other `conditions constant, decreases or increases
the molecular'weight of the polymer. Acrylo- L
nitrile copolymers and interpolymers containing
e at least 85% by weight of acrylonitrile and like- ’
`merizable substances such as, for example, com
pounds containing one or more ethylenic link
ages including vinyl and acrylic compounds as ,Y
Well as oleñnic or diolefinic hydrocarbons such as ,
wise preferably having a molecular weight of 20 isobutylene, butadiene, etc. They are eminently
15,000 to 250,000 or higher can be prepared in a
satisfactory'for use with those polymers that con
similar manner.
tain an appreciablevamount of acrylonitrile, for
The following examples in which parts, pro
example, polymers, copolymers and interpoly
portions Aand percentages are'by weight unless
mers that contain at least 85% by weight of
otherwise speciñed illustrate preferred methods 25 acrylonitrile and that have generally been re
of preparing solutions of polymers in accordance
garded by the art as being completely insoluble
with the principles of this invention and of em
ploying these solutions in the manufacture of
commercially satisfactory shaped articles of the
polymer. The invention is not to be limited b 30
the details set forth in the examples.
Example I
>Fifteen (15) parts of an acrylonitrile polymer
in all common organic solvents. Nor are these
solvents limited to use with a polyacrylonitrile
of any given molecular weight. They can be used
with a polymer of' almost` any given molecular
Weight and are especially satisfactory for use
with those polymers having an average molecular
weight within the range 15,000 to 250,000 as de
termined by viscosity data using the Staudinger
prepared by the polymerization of monomeric 35 equation and intended for. use in the manufac
acrylonitrile in accordance with the disclosure of
ture of yarns or iilms.
U. S. Patent No. 2,160,054 to Bauer et al.` and
The solution of acrylonitrile polymer dissolved
possessing an average molecular weight of 120,000
in an organic solvent in accordance with this
as determined by the Staudinger equation from
invention must be of such a concentration that
viscosity data were ground to an average particle 40 its viscosity at the operating temperature is with
size of 200 mesh and intimately mixed with 85
in a workable range. When it is to be employed
parts of similarly ground dimethyl cyano acet
in the spinning of yarn or the casting of ñlm, the
amide. The mixture was heated to 120° C. to
solution should preferably have a viscosity within
form a clear, homogeneous dispersion or solu
the range 25 to 750 poises.
When the polymer
tion. When cooled to room temperature, it set 45 has a molecular Weight of 250,000 or more, this
to a clear, gel-like mass, which mass however
requires that the maximum concentration _of
again returned to solution form upon-heating to
polymer in the spinning solution be of the o_rder ~
above 60° C. The solution heated to a tempera
of 10%. Generally, it is preferred that the spin
ture of 100° C. was extruded through a 10-hole
ning solution contain at least 10% of the polymerv
spinneret (hole diameter of 0.003 inch) into a 50 because of the diñiculty of rapidly- removing large
bath comprising glycerol heated to a temperature
amounts of solvent from the solution in the
of 140° C. Y-The resulting multiñlament yarn of
spinning operation. Moreover, it is economically
acrylonitrile polymer was washed with water and` '
undesirable to use such large amounts of solvent
for the spinning of a >given amount of polymer
Example II
55 although- it is true that the solvent can be com
Forty (40) parts of the acrylonitrile polymer
of Example I were mixed vwith 60 parts of gamma
pletely recovered from the spinning operation
and reused. For these reasons, itis preferred
to employ a polymer having an` average molecular
methyl-gamma-NN-dimethyl carbamyl pimelo
-nitrile and heated to a temperature of 175° C.
weight of lbetween 40,000 and 150,000 since such ,
to form a clear, homogeneous dispersionl or solu 00 la polymer forms a solution of the desired vis
cosity in concentrations of the order „of 15% to
tion. ’I'he solution was cooled to 25° C. to form
25% andat a desirable spinning temperature of
a clear, solid mass which was ground to a iine
the order of 100° to 150° C. OI course,- it is
particle size f 20 mesh). This powdery mass was
within the scope of the invention to heat the solu
- molded at a temperature of 200° C. and a pres
tion to a higher temperature, even to above the
sure of 500 pounds to form a tough, durable, rod
like structure, the structure being clear and free
of haze.
normal boiling point of the solvent, for the actual
spinning operation. Here again, the controlling
factor with regard to the temperature of the>
spinning solution is the viscosity of the solution.
The evaporative medium employed in the-dry
a solution of polyacrylonitrile, or a copolymer'or 70
spinning of filaments and yarns or the dry cast
interpolymer of acrylonitrile which is eminently
ing of films in accordance with this invention
suited for use in the manufacture of shaped arti
cles such as yarns, films, or molded articles. The
may be any vapor inert to the film- or filament
solutions are also suited for use as lacquers or
forming solution such as air, nitrogen, steam,
coating compositions. They are especially useful 76 etc., or any suitable mixture thereof. The tem
As indicated in the above examples, it is pos
sible by the practice of this invention to obtain
added in the desired amount to an already
formed solution of the polymer in a lower boiling
solvent, for example to a solution of the polymer
perature of the evaporative medium is dependent
on such factors as the dimensions of the spin
ning cell, the composition and rate of extrusion
of the spinning solution and the rate of flow of
the Aevaporative medium. It is only necessary
in dimethyl cyano acetamide.
This invention is primarily concerned with' the
steps of dissolving polyacrylonitrile in a suitable
that these several factors be so correlated that
solvent to form a stable solution adapted for>
the yarn or other shaped article leaving the spin
use in the manufacture of shaped articles of
ning cell be sufficiently freed of the solvent so
polyacrylonitrile. vIt is characteristic of the in
that it is solidified and capable of being wound
10 vention that the solutions provided by it are sta
into package form or otherwise collected.
ble; the solvents do not cause a decomposition
As indicated in Example I above, shaped arti
or chemical alterationy of the dissolved acryloni- `
cles of acrylonitrile polymer can also be formed
trile polymer. At the same time, it is also'char
by extruding the spinning solution into a suitable
acteristic that the solvents provided by the inven
precipitating bath comprising a liquid that is
tion are also useful in th'e dissolving of mixtures
miscible with »the solvent but~ is a chemically
of polyacrylonitrile and adjuvants such as dye
inert non-solvent for the acrylonitrile polymer.
modifiers, linear- polyamides such as nylon, de
As examples of such a liquid may be mentioned
rivatives of cellulose including cellulose ethers
water, glycerin, organic solvents such as alcohol,
and esters, polymers of vinyl compounds such as
ether, etc., or aqueous solutions of salts, alkalines
i or acids.
The copending application of William 20
` W. Watkins, Serial No. 496,376, filed July 28, 1943,
covers the use of glycerol and aqueous solutions
of salts as baths, preferably at elevated tempera
tures, for the wet spinning of acrylonitrile poly
mer yarn, from solutions of the polymer, pref
vinyl chloride, vinyl acetate, acrylic acid, etc.,
which adjuvants may be incorporated in the
acrylonitrile polymer solution to modify the
properties, both chemical and physical, of the re
sulting shaped articles.
This invention provides a class of solvents for
erably with substantial tension and stretch being
polyacrylonitrile, and copolymers and interpoly
applied vduring spinning.
mers of acrylonitrile which were heretofore con
The article of acrylonitrile polymer thus ob
sidered substantially insoluble. The solvents >are
capable of forming with the polymer clear solu
stretching operation of the type employed in the 30 tions that are stable for extended periods of time
and are admirably suited for use as lacquers or
above examples. This stretching is preferably
coating compositions or in the manufacture of
performed by passing the yarn between two posi
-shaped articles of the polymer, for example by
tively driven rollers,> the peripheral speeds of
tained can advantageously be subjected to ya
which are so adjusted that the article is stretched
from two to ten times its original length, prefer
ably approximately six times its original length.
This stretching of the formed article may be
performed at any suitable time. However, in
the case of articles formed by the wet spinning or
casting technique, it is preferably performed be
fore the article has been completely dried. The
orientation of the structure thus obtained im
proves the physical properties of the structure
including its tenacity, its resilience, etc. `
extrusion into an evaporative or coagulative me- '
dium, or bythe use of a molding technique.
The invention also provides a class of mate
rials that'is. eminently suited for use in plasticiz
ing structures comprising the acrylonitrile poly
mers. The materials provided by this invention
40 are apparently true solvents for the above-men
tioned'acrylonitrile polymers. They do not tend
to react with or decompose the polymer, the poly
merio material obtained from the solution of this
invention apparently being the same identical
This stretching of the shaped article can also 45 chemical composition -as the initial polymer.
be accomplished by causing the article, while
passing between stretching rollers„to contact .a
Yarns, films and similar articles of polyacrylo
nitrile prepared from the solutions of this inven
tion can be stretched to yield oriented structures
heated stationary pin or to pass through an inert
that possess a high tenacity. a desirable elonga
medium such as air, water, glycerin, etc. heated
to a high temperature.V Obviously, the article 50 tion and a high' elastic recovery that compares
favorably with that of silk. The articles are not
must not be exposed to this high temperature for
contaminated with undesirable salts and they are
a period suñiciently long Ito decompose the poly
substantially free of void spaces.
mer. In general however, the time of contact of
Reference, throughout the speciñcation and
the article with the heated medium is so short
that temperatures up to 250° C. can be employed. 55 claims, to acrylonitrile polymers, polymers of
acrylonitrile, and copolymers and inter-polymers
Although it is generally preferred to heat the
of acrylonitrile “containing at least 85% by
article to a temperature of at least 100° C. during
weight of acrylonitrile” signifies polymers con
the stretching operation, this is not'essentlal.
in their molecules at least 85% by weight
Desirable results can be obtained by stretching
the article without the application of heat, for 60 of the acrylonitrile unit which is considered to
be present in the polymer molecule as the group
>example by stretching at room temperature.
In addition to acting as solvents for polyacrylo
nitrile, or copolymers of acrylonitrile, the ali
phatic or arylaliphatic nitrile compounds of this
that is, at least 85% by weight or the reaetant
invention, when present in small amounts, can
material converted into and forming the poli' '
also be used as plasticizing agents for the poly
is acrylonitrile.
mer and the higher boiling compounds of the in
Since it is obvious that m
changes and
`vention are especially suited for such use. At the
modifications can be made in the above described
same time, it is, of course, to be understood that
details without departing from the nature and
non-solvent softeners, such as glycerol, can also
be incorporated in the solutions ofthe invention.
these materials remaining in the subsequently
formed articles to impart a softening effect. If it
is desired to use such plasticizing or 'softening
agents with -polyacrylonitri1e, they are preferably
a spirit of the invention, it is to be understoodthat
the invention is not to bev limited to the details
described herein except as set forth in the ap
I claim:
1. As a new composition of matter, a
cule at least 85% by weight of acrylonitrile dis
solved in N,N-dimetliyl-beta-cyano propionamide.
of acrylonitrile containing in the polymer mole
cule at least 85% by weight of aorylonitrile dis
10. As a new composition of matter, a polymer
solved in a dimethyl amide nitrile compound, said
compound embraced within the formula:
of acrylonitrile containing in the polymer mole
cule at least 85% by Weight of acrylonitrile dis
solved in beta-cyano-beta'(N,N-dimethylcarbamyl) diethyl ether,
11. As a new composition of matter, a polymer
of acrylonitrile containing in the polymer mole
cule at least 85% by weight of acrylonitrile and a
dimethyl amide nitrile compound, said compound
wherein m and q are integers at least; equal to l;
n and p are integers of such value that n/m does
not exceed 1.5 and p/q does not exceed 1.5; all
valences of said compound other than those con
embraced within the formula: v
tol-t teal
' tained in carbon-to-carbon linkages and not
shown as satisfied in the formula being satisiied
by a substituent. taken from the group consisting
of hydrogen, halogen, oxygen, bivalent sulfur, hy
wherein m and q are integers at least equal to 1;
droxyl, thiol, cyano, thiocyano and sulfoxy; the
total number of halogen, oxygen, sulfur, hydrox
yl and thiol substituents not exceeding one half
n and p are integers of such value that 11,/ m does
not exceed 1.5 and p/q does not exceed 1.5; all
valences of said compound other than those con
tained in carbon-to-carbon linkages and not
shown as satisñed in the formula being -satisñed
by a substituent taken from the group consisting
thev sum oí 'm-i-q and the total number of cyano,
thiocyano and sulfoxy radicals not exceeding the
sum of m+q.
2. A new composition of matter as defined in
claim 1 in which the polymer of acrylonitrile is 25
3. A new composition of matter as deñned in
claim 1 in which the polymer of acrylonitrile is
non-reactive with said dimethyl amide nitrile
4. A new composition of matter as deñned in
claim 1, in which said polymer is non-reactive
with said dimethyl amide nitrile compound, but
is soluble in all proportions therewith,
5. A new composition of matter as deñned in
claim 1, in which the polymer of acrylonitrile has
a molecular weight of between 15,000 and 250,000.
of hydrogen, halogen, oxygen, bivalent sulfur, hy
droxyl, thiol, cyano, thiocyano and sulfoxy; the
total number of halogen, oxygen, sulfur, hydroxyl
and thiol substituents‘not exceeding one half the
sum of m+q and the total number of cyano,
thiocyano and sulfoxy radicals not exceeding the
sum of m-i-q.
12. The composition of claim l in which the
solution contains at least 10% of said polymer
of acrylonitrile.
13. The composition of claim 1 in which the
polymer of acrylonitrile is polyacrylonitrile hav
' ing a molecular weight of between 15,000 and
6. A new composition of matter as deñned in
14. The composition of claim 1 in which the
'claim l, in which the polymer of acrylonitrile has
polymer of acrylonìtrile is polyacrylonitrile hav
a molecular weight of between 40,000 and 150,000. 40 ing a molecular weight of between 40,000 and
'7. A new composition of matter as defined in
claim 1,_ in which the polymer solution has a vis
cosity between 25 and 750 poises.
8. lAs a new .composition of matter, a polymer
which said polymer is polyacrylonitrile.
of acrylonitrile containing in the polymer` mole
cule at least 85% by weight' of acrylonitrile dis
which said polymer is polyacrylonitrile.
solved Ain N,N-dimethylcyanoacetamide.
which said polymer is polyacrylonitrile.
_ 15. The composition as- deñned in claim 9 in
16. The composition as defined in claim 10 in
17.'The composition as deñned in claim 8 in
9. As a newv composition oi matter, a polymer
of acrylonitrile containing in the polymer mole
-Certiñcate of» Correction `
Patent No. 2,404,716.
July 23, 1946.
the above
It is hereby certified that errors'appear in the printed specification of
2, line 9, for
numbered patent re airingl correction as follows: Column. line
7, claim l, and column
niti'ile” read polyacry onitmie; column 5, line 32; column l5,
“C” after the third bracket,
i6, line 15, claim ll, for the indistinct subscript following formula reading
read p; column 7, lines 66 to 68,_for that portion oi the
"a,' re'ad im
columny 13,` line 19, for “alkalines” read alkalies; and that the said Letters Patent
should be read with these corrections therein that the same may conform to the record
of the case in the Patent Oíiice.
Signed and sealed this 5th day of November, A. D. 1946.
. ï LESLIE imma,
First Assistant Oommîasíoner of Patents.
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