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Sept. 24, 1946.
F_ CLATWOOD
2,408,026
PROCESS ‘FOR TREATING SYNTHETICALLY SHAPED PROTEIN BASE MATERIALS
Filed Jan. 23,_ 1942
15
BY
ATTO EY:
Patented" Sept. 24, 1946
UNITED STATES. PATENT c'OFFI‘iE;
PROCESS FOR TREATING SYNTHETICALLY .
SHAPED PROTEIN BASE MATERIALS
Francis Clarke Atwood, Newton, Mass, assignor, '
by mesne assignments, ‘to National Dairy Prod
ucts Corporation, New York, N. Y., a corpora
tion of Delaware
Application January 23, 1942, Serial No. 427,940
4 Claims. (01. 8-1273)
This invention relates to the formation of syn
thetically shaped protein base containing mate- ‘
rials.
-
The invention includes, more particularly, the
formation of vsynthetic materials made from an
alkali-soluble acid-coagulable protein as a base
material, such as an animal and vegetable casein;
' such animal casein is typi?ed by the casein ob
tained from milk, and the vegetable casein is
, periods of time'such ?ber also tends to deterio
rate so as to become brittle or lose its strength
and softness. Such ?ber also reacts in an un
desirable way with many chemical agents such
as dyes. These various properties of proteins
may be considered generally as chemical prop
erties, i. e., the ability of the protein to combine
physically or react chemically, or resist such com
bination with oxygen, water, acids, alkalies and
typi?ed by the protein obtained from soybean, 10 other chemicals such as dyes.
‘
.
castor bean and similar sources of the alkali-sol
While the physical properties of ?ber prepared
uble acid-coasulable proteins.
from the proteins such as casein, including the
The invention may be applied to the manufac
ture of synthetic protein base materials in a
variety of forms such as ?lm, ?ber, and products
that are cast, extruded or molded into other
shapes. For simplicity, however, the invention
will be described primarily with reference to the
common method of soaking the shaped casein
?ber in formaldehyde solutions are satisfactory
for some purposes, they are far from satisfactory =
for most uses to which ?bers are to be put. with
respect to their chemical properties particularly
they leave much to be desired. For example, a
> formation of ?ber made arti?cially from animal
?ber prepared from a casein dispersion and coor vegetable casein as a base, more particularly,
agulated, in which process it is hardened by ‘the
the casein derived from milk. Such a ?ber has 20 usual
treatment with formaldehyde, is not re
been referred to variously as synthetic wool, syn- sistant to hot-water or dilute acids or alkalies.
thetic silk and synthetic fur. Since the ?ber has - I Particularly is this so if the water solution con
unique properties not identical with any of the
tains an alkaline material such as would be pres
above, I have suggested that it be referred to by
ent in a hot solution ofan ordinary soap. Upon ‘
the generic ‘term “prolon," or simply as synthetic 25 the heating or boiling of such ?ber in such a
protein or protein base ?ber.
solution it becomes soft and spongy and takes
While‘ the process by which my new ?ber is
on a “slimy feel." The tensile strength of the
made utilizes a protein as the base material, the
?ber and its elasticity in such a state is also
final ?ber is not of the same chemical constitu
greatly reduced so that the ?ber is readily de
tion, nor does it have the same chemical or physi 30 formed or broken. Upon drying such ?ber after
cal properties, as the protein. The finished ?ber
it has been subjected to such treatment, it be
probably cannot be termed a protein in the strict
comes brittle so that further handling results
sense of this word, and for this reason I have
in excessive “droppings," if in fact the ?ber is
used the expression "protein base" to distinguish
su?lciently ?exible to be subjected to any fur
the material of'my ?ber from ?ber that is a true 35 ther processing. Ordinary casein ?ber, in addi
protein.
tion, does not have dyeing properties enabling it
Protein-containing materials have many de
sirable properties that render them valuable for
- to be dyed in a manner similar to naturally oc
curring proteinaceous ?ber. The ordinary casein
many uses, such as covering and decorative ma 40 ?ber also is subject to a change in properties-due
terials and upholstery, including woven fabrics
to contact with moisture in the air. . In humid
and felts, and for the use in articles of clothing
air it is relatively plastic, but in dry air it is quite
including clothes, shoes, gloves and hats. These
properties include warmth, softness, ?exibility,
tensile strength, elasticity and other similar prop
erties‘possessed by‘ protein-containing materials.
brittle.
_
From the above it will be seen that the syn
.45
thetic protein ?ber as known heretofore in the
art, such as that shaped from casein" and hard
ened with formaldehyde, is entirely di?’erent
from natural proteinaceous ?ber such as wool,
These properties may be viewed in general as
physical properties and will be so referred to
herein.
silk or fur, and is not suited for the uses to which
The‘proteins are composed essentially of car 50 such natural ?bers may be‘ put. This difference
bon, hydrogen, oxygen and nitrogen and may ‘is so marked as not to be'simply amatter of
contain small amounts of sulfur or phosphorus
degree. Apparently the casein inherently is of
or both. They vary somewhat in their chemical
such a nature as not to possess satisfactory prop
reactivity depending upon their exact chemical
erties for ?ber purposes.‘ Attempts at modi?ca- .
' constitution, both from the standpoint of their 55 tions of the casein have not ‘produced a ?ber
empirical composition as well as their'structural
which has satis?ed thertextile industries.
1
composition.‘ Ordinary synthetic casein ?ber, for
I have discovered that an- entirely new‘ ?ber
example, is affected adversely by hot water, al
may be made, utilizing protein as the principal
kaline or soap solutions and dilute acid solutions
base material, but which neverthelessvpossesses
such as are encountered in dyeing. Over long 60 desirable chemical properties and is not subject
2,408,026
3
- .
to the in?uences that affect ordinary casein ?ber,
and at the same time has physical properties that
are improved or at least not inferior to the known
synthetic protein ?bers. I believe that the chem
ical composition of the ?ber is entirely different
from that of the protein used as the base mate
rial and that this difference is largely responsible
for the desirable properties of the ?ber.
In accordance with my invention a ?ber may
4
This new chemical compound or Composition can
be made and then given the shape of ?ber, or the
protein ingredient can be shaped and the reaction
of the protein and formaldehyde and anhydridc
can be ‘carried out while the protein is in the
shaped form. It is the latter procedure that I
prefer because this makes it possible to delineate
or orient the protein molecule and then form the
new compound using the delineated protein as the
material.
.
,
‘
be produced thatvis relatively resistant to chem 10 base
In particular, I have discovered that if syn
ical activity of the undesired type, such as break
thetic protein ?ber is treated with a formaldehyde
down by bleac 'ng agents and deterioration by
solution and‘ then acylated with an acid anhydride
hot water, acids or alkalies, while at the same time
under certain conditions hereinafter set forth,
it has desirable chemical properties imparted to
‘the ?ber is relatively resistant to water, and ‘acid
it with respect to its \reaction to dyestuffs and 15 and alkaline solutions; its ‘ chemical reactivity
chemicals ordinarily used in the processing of
with respect to‘chemical substances, such as dyes,
naturally occurring proteinaceous ?bers. In ac
is such that it may be dyed by processes substan
cordance with the invention, the ?ber also remains
tially identical with those heretofore used for
soft and pliable and retains or even has its tensile
dyeing natural protein ?bers, such as wool, silk
strength and other physical properties improved.
and fur; and it has the other desirable physical
It acquires properties normally desired by textile
.and chemical properties set forth herein. ‘
operators as to its moisture content,'or the mois
More particularly, I have discovered that in the .
ture content of the air with which it is in contact.
The process of my invention produces a new
above process the anhydride should be in ad
mixture with a de?nite proportion of a free acid,
?ber~ that can withstand boiling for long periods 25 which may or may not be the same acid as that
of time in water, as well as inhot dilute acid
corresponding to the anhydridc, said anhydride
solutions such as are used in dyeing. It is also
and acidbeing in an inert solvent and said treat
enabled to withstand vigorous‘mechanicaltreat
ment being under de?nite controlled conditions
ment combined with alkaline material, such as
as to temperature, concentration of anhydridc,
“fulling” and “scouring” operations, even after 30
'time of treatment, and concentration of acid. ‘
it for dyeing operations’.
7
In accordance with my invention it is also
- preparing
The new synthetic protein base ?ber produced
in accordance with my invention, not only is re- ~
' sistant to dyeing operations, but has desirable
properties in that itaccepts dyes ordinarily ac
possible to carry out the process in such form
that the critical relation between the acid and
35 the anhydride may be kept substantially con
stant throughout repeated treatments of addi-.
tional quantities of the protein material.
cepted by natural protelnaceous?ber and rejects
dyes which are not accepted by natural protein
?ber.
Still further in accordance with my invention
it is possible to carry.’ out the process under such
Since one of the more important uses of
the synthetic protein base ?ber is in admixture
conditions as to recover substantially all of the
with natural protein ?ber, it is desirable’that the 40 solvent, anhydride and acid, with the exception
two should have similar dyeing properties. Not
of the anhydride which has reacted during the
only does the ?ber behave similarly toward the
treatment
of the material.
same dyes, but it accepts the dye at substantially
The synthetic protein ?ber that'is ‘to be re
- the same rate so that at the end of the dyeing
with formaldehyde and the anhydride in
operation of a mixture of natural and synthetic 45 acted
accordance with my invention may be made by
protein base ?ber, all of the ?ber will be of sub
any known processes in which the protein is
stantially the same shade.
,
dissolved or dispersed with an alkaline material,
such as caustic, or in an organic alkaline mate
rial such _as' amines. Softening or modifying
new dyes and new dyeing techniques because of 50 agents may be added, but are not essential. The
It will be recalled that upon the development
of the rayon industry it was necessary to perfect
the different chemical constitution and different
protein dispersion is then extruded through the
physical properties of the rayon ?ber.‘ Such an
small holes-of a spinnerette and coagulated in
approach mightsimilarly have been made with
respect to the synthetic protein ?ber. I prefer,
?ber form by means of an acid. ' The ?ber is then
treated with formaldehyde, washed and dried.
however, not to do this. Rather than develop new 55 So much of my process is known to the art and
dyes and new dyeing technique for. the known
the exact details by which the ?ber is produced
synthetic protein ?ber I prefer to‘make a new
up‘ to this stage of the process are not critical
?ber that may be’ treated by the niéthods and
in so far as my invention is concerned, except as
dyes that are standard in the protein ?ber indus
tries, such as the woolen industry, the silk 60
industry or the fur felt industry, for example, the
‘hat industry.
In accordance with my invention, therefore,
, I. produce a ?ber having dyeing properties simi
lar to those of natural protein ?ber, both with re
spect to its behavior to different dyes and its
dyeing rates.
‘
A more detailed description of the chemical
composition of the ?ber and its properties is set
above indicated.
'
A protein ?ber that has been given a thorough
treatment with formaldehyde, such as by soak
ing it for a long time in a formaldehyde solu
tion, apparently does not have the formaldehyde
65 permanently combined with it. Such ?ber upon
treatment with water or aqueous solutions, readily
yields at least a portion of its formaldehyde,
either because it is held only in a more or less
physical relationship,vsuch as adsorption or ab
sorption, or if chemically combined easily yields
forth hereinafter following the description of the 70 it through hydrolysis. At any event, the form
process by which it is made.
aldehyde is not combined with such permanence
The ?ber produced in accordance with my in
as will permit the ?bers to retain their hardened‘
vention may be regarded broadly as the reaction
state upon prolonged aqueous treatment. This
product of an alkali-soluble acid-coagulable pro.
is con?rmed by statements in Sutermeister and
75
tein, formaldehyde, and an acylating anhydride.
2,408,026
Browne which states that when casein is treated
with a' formaldehyde solution for 16 days the re
sulting formaldehyde-casein product was insol
The amount of formaldehyde so absorbed of‘
loosely combined should be at least 2% and ‘pref
erably 3 or 4%. based on the dry ?ber'before
treatment.
uble in- water and was not swelled when treated
with dilute acids. However, when the formalde
The‘ amount of formaldehyde absorbed or
‘loosely combined may be determined by any suit
able technique. I have found it convenient to
hyde-casein product was suspended in water, and
subjected to steam distillation, practically all of
the so-called “bound” formaldehyde was found - take a sample of wet ?ber of a given weight with
in the distillate. The remaining product showed‘
known moisture and solids content and treat it
inlcertain tests the properties of unaltered casein. 10 with formaldehyde solution of a known concen
This is further evidenced by the fact that the '
tration for thegiven desired time period, or until
literature contains references to methods for test
equilibrium is reached under the treating condi
ing casein ?ber (to distinguish it from wool) by
tions.
The ?ber is then removed and the con
_ determining the amount of formaldehyde in such '
centration of the formaldehyde solutions after
?ber. (Klepzig’s Textile-Z. 41, 463-6 .(1938) and 15 treatment again determined. Sincesome water
Helv. Chim. Acta 24, 237-42 (1941).) - Such tests
is given off by the ?ber because of its initial
show that the formaldehyde is present in ordinary
moist condition and possibly also because of the
casein ?ber in such a way thatit can be separated
reaction with the formaldehyde, it is necessary
or released so as to be determined quantitatively.
to determine the moisture content of the fiber
'Not only is the ‘formaldehyde readily liberated,
before and after the formaldehyde treatment.
but upon boiling such prior art ?ber with water
From the amount of formaldehyde in the solution
or weak acid the ?ber goes to a gelatinous-like
of initial concentration, and from the amount
mass losing its ?ber identity and drying to a hard,
of formaldehyde'in the solution after treatment,
brittle substance. Also such prior art ?ber loses
‘(taking into account the moisture in the ?ber
a substantial portion of its weight during the
before and after treatment) "the amount of
boiling test used in the formaldehyde determina
formaldehyde removed from the solution (and
tion.
absorbed by the ?ber) can be determined and
In contrast with the above, and in accordance
the percentage on the dry weight of the ?ber
with my process, formaldehyde introduced into
can similarly be calculated.
7
the ?ber is combined during the anhydride treat
The amount of formaldehyde in the solution
ment in some new way such as to produce a new
is determined by the standard sul?te' method for
?ber having different properties.
analyzing for formaldehyde.
In accordance with my invention, the formalde
,
That formaldehyde is combined with the pro
tein in my new ?ber in a different and new chem
hyde treated ?ber is subjected to treatment with
ical way is indicated by the fact'that the ?ber is
vastly more stable against various chemical de
the acid and the anhydride being present within
teriorations including hydrolysis, thereby show
an acid anhydride in admixture with free acid,
_ a fixedv ratio of amounts. Anyanhydride exert
ing that at least a part of the formaldehyde is
ing an acylating action may be used, such as the
not merely absorbed or held by the protein in
anhydride of a carboxylic acid._ The anhydride
some loose chemical way,‘ but rather that it enters 40 may be of an acid that is the same as the free
into a reaction in the acylating process to pro
acid used in the process or it may be different.
For example, the anhydrides of acetic acid, such
duce a new molecule which is a chemical com
bination of the several reacting ingredients. This
as acetic anhydride or ketene may be used with
is further demonstrated by the fact that my new
acetic acid, or acetic anhydride ‘or ketene may
?ber is di?'erent than the product obtained when 45 be used with other acids, such as formic, maleic,
a ?ber is acylated which has not had a previous
malic, stearic, lactic, butyric or phthalic acids.
formaldehyde treatment.
Anhydrides of acids other than acetic acid may
.
The difference between my new ?ber and prior
?ber is further indicated by the fact that my new
?ber, upon boiling with ‘water or a weak acid, 50
retains its ?ber identity and substantially all of
its physical characteristics after the boiling oper
ation. In addition, its loss of weight is not more
than about 2 to 4%, thereby indicating that any
be used, such as phthalic anhydride, propionic
anhydride, lactic anhydride, maleic anhydride,
butyric anhydride, stearic anhydride, adipic an
hydride, succinic anhydride, cinnamic anhydride,
lauric anhydride,. benzoic anhydride, or mixtures
thereof, with the corresponding acid or with other
acids.
changes in the ?ber during boiling are relatively
While any of the above materials may be used
insigni?cant insofar as they a?fect its properties 65 in accordance with my invention, I will describe I
and utility as ?ber. _
an illustrative embodiment utilizing acetic anhy
I stated previously that the ?ber should be
dride and acetic acid, since these are relatively
treated with formaldehyde so _ as to have the
inexpensive materials and are readily available
- formaldehyde absorbed or loosely combined with
in the open market in adequate quantities for
the protein at the time of the treatment with 60 practicing the invention on a. commercial scale.
the anhydride. The ?ber may be treated with
Reference may also ‘be had to the attached
formaldehyde in any conventional manner as by
sheet of drawings which illustrates an apparatus
- immersing it in a formaldehyde solution or treat
which may be used in practicing the invention.
ing it with formaldehyde vapor,
“
Referring more particularly to the drawing, a ‘
In my application Serial No. 417,024, ?led Octo
ber 29, 1941, I have described a method of treat
centrifuge is indicated generally at I, preferably
of relatively large dimensions. The centrifuge
ing protein ?ber with formaldehyde, in which
is provided with a perforated basket 2 mounted
the pH and temperature are controlled whereby
a maximum amount of the formaldehyde is com
bined with the protein in a minimum of time.
.This process may be employed, although the
standard procedure of soaking the ?ber in the
ordinary formaldehyde solutions for a long time,
for example, 12 hours, may also be used.
75
for rotation by suitable motor 3. The centrifuge
is provided with coils 4 through which steam or
any heating or cooling medium may be intro
duced by means of a valve 5, and withdrawn by
an exit valve 6. The centrifuge is provided with
a cover ‘I which may be secured to the centrifuge
by means of suitable clamps 8, which may be
'
‘2
l
.
a large centrifuge, a suitable lifting or counter
8
‘the treating operation. Also since the reaction
spaced around the centrifuge so as to hold the
cover tightly. Gaskets or washers to provide a
tight seal may be used in the conventional man
'ner. Since the cover is relatively heavy in such
forming the new ?ber is exothermic. the circu
lation of the liquid through the ?ber prevents
5
local overheating. 'In order that the tempera
ture of the liquid may be kept at the desired point
balancing means 9 is provided for raising and
or raised during the treatment, steam or other
lowering the ‘cover.
heating medium may be introduced through the
'
v
‘
‘
A supply tank i0 is provided of suchdimensions
pipes 4. Ordinarily the operation is carried out
at atmospheric pressure within the centrifuge, but
least sufficient to ?ll the centrifuge._ This tank 10 it will be apparent that the structure utilized per—
mits superatmospheric pressure, if this is desired.
may be elevated above the centrifuge so that
Following the treating operation, the valve i5
the liquid may be withdrawn therefrom by
is opened and the treating liquid drains from the
gravity through a pipe H and introduced into
fiber and is returned to the supply tank by means
the centrifuge by means of a valve i2. A pump
as to hold the treating liquid in an amount at
‘ i3 is provided by means of which the liquid may 15 of the pump. l3.
After all of the liquid that will .
drain from the ?bers has beenpumped from the
centrifuge, the centrifuge is operated at high
speed for a few minutes. The centrifugal force
liquid through the pipe i6 into the supply tank.
removes a large portion of the liquid. This liquid
If desired the tank may be below, the centrifuge
and the liquid pumped from the tank to the cen 20 drains into the bottom of the centrifuge and is
removed therefrom and returned to the supply
trifuge and returned by gravity.
'
be removed from the centrifuge through a pipe
M by way of a valve I5. The pump returns the
The supply tank is provided with heating‘coils
I‘! through which steam or other heating: me
dium may be passed to heat the liquid in the
tank (by the pump I3. .:
'
,
_
The size of the centrifuge is not critical, but
it is preferred to use one holding from 200 to 500
pounds of ?ber at a time. A centrifuge having
a rotatable basket ?ve feet in diameter is suit
able for this purpose. During a centrifuging
operation,
this may develop a centrifugal force
be mentioned hereinafter, a treating chamber i8
of about 200 g., which is effective for separating
is provided. This may be equipped with agitating
paddles I8a driven by a motor l8b. When the 30 most of the treating ?uid from the ?ber.
Aftenall'of the liquid has been removed from
liquid is to be modi?ed, it may be’withdrawn from
the ?ber, the valve I5 is closed, and the valve
the supply tank through a pipe 2| by way of a
21 is then opened. A vacuum is applied to the
valve 22 and ‘introduced into the chamber l8.
supply tank to the desired temperature.
In order to modify the constitution of the treat
ing liquid .in the supply tank for the purpose to
Following the treatment the liquid may be dis
centrifuge to create an absolute pressure as low
lected. The treating liquid may be separated
from any water by stratification and withdrawn
through a valve 3| and returned through a pipe
not su?lcient to vaporize the remaining liquid
charged into‘a centrifuge H! by way of a pipe 35 as is ‘feasible with apparatus of this type. A
vacuum of 25 to 29 inches is desirable, and one
190 and a valve l9b. This centrifuge has a basket
as low as 28 inches is preferred. At this low,
Illa rotatable by a motor 20. Following centri
pressure the liquid is quite volatile and the latent
fuging the liquid may be pumped back into the
heat in the ?ber, together with any additional
supply tank by means of a pump 23 by way of
heat which may be supplied, is sufficient to vapor
a valve 24 and a return pipe 25.
_
ize substantially all of the liquid which has not
Connected with the treating centrifuge Us a
been removed from the ?ber during centrifuging.
conduit 26, leading through a valve 21, to a con
‘ The liquid is condensed in a condenser 28 and
denser 28. A vacuum pump 30 is connected with
after separation from any water in the receiver
the condenser through a pipe 29. By this arrange
ment it is possible to place the treating centrifuge 45 30 is returned. to the supply tank by way of the
conduit 32 and the pump l3.
_
under vacuum when it is desired. Connected with
If the sensible heat in the ?ber, and that which
the condenser 28, through a conduit 29a, is a
may be introduced by means of the coils l, is
receiver 30 in which the condensate may be col
32, through the pump l3, and to the supply tank
by way of the pipe l6. Any water separated from
at the vacuum employed, it is possible to admit
a suitable amount of very hot‘ air into the cen
trifuge; this facilitates vaporization of the treat
ing ?uid.
‘
However, due to the poor heat conductivity of
the ?ber and the dimculty in introducing heat
pipe .33.
55 except by a circulating liquid, I prefer to remove
vThe ‘treating chamber I8 and centrifuge l9
‘so much of the liquid by centrifugal forces as to
are also connected to a, condenser 28a and~an '
leave no more of the liquid on the ?ber than can _
exhausting pump 30a by means of conduits 34
be evaporated by the latent heat in the ?ber at
connected through valves 35. By this means it is
,
also possible to exhaust vapors from the chamber 60 the reduced‘ pressure employed.
After this operation the vacuum valve 21 is
l8 and centrifuge l9 and condense them. The
closed and the cover removed from the centri
above apparatus is illustrative and other ex
fuge. The treated fiber is then removed, washed
amples of apparatus will occur to persons skilled
and treated by any subsequent processing oper
in the art.
the solvent can be removed from the over?ow
..
When it is desired to'treat the ?ber, a quantity ' 65
is placed within the centrifuge basket 2 and
the cover ‘I is tightly secured thereto by means
ation desired.
’
i
The liquid used in the treatment contains the
anhydride and-the acid in required'proportions.
Preferably these are contained in an inert sol
of the clamps 8. Valves l5 and 21 ‘are closed
and treating liquid admitted from the supply tank
‘vent which acts as a diluent.
i 0 by means of the valve l2 until the ?ber is cov
ered with the liquid. The ?ber is then allowed to
' inertness with respect to the anhydride, the acid
stand in contact with this liquid for the required
length of time and if desired the centrifuge may
be operated very slowly so as to obtain uniform
.
The solvent should be selected because of its‘
and the protein being treated, as well as its sol
vent action on the anh'ydride, at the tempera
tures employed. The boiling point of the sol
admixture of the liquid through the ?ber during 75 vent preferably is above the temperature at
9,408,028
-
a "which the treating operation .is carried out so
as not to require superatmospherie pressure dur
1o
ing the cost of heat, the‘ amount of ?ber that
must be treated per day in a given amount of
ing ‘the, treatment, but the boiling point also
equipment, and the price of anhydride. Within
the ?gures set forth above. and in view of the
should not be too high above the treating tem
perature so as not to prevent evaporation of the
liquid when. the vacuum is applied subsequent to '
principles announced herein, anyone skilled in
the art will be enabled to relate these factors
taking into account the economics ‘involved and
the type of property desired. In general, I prefer
the. treating operation. In general, it is pref
erable that the ‘boiling point of the solvent should
be above that of water, so as to facilitate sep
to use a treating temperature between 180 and
aration of water in vapor form from the solvent. 10 200°
F., a solvent having a boiling point of be
If, for example, the liquid is to be heated to a
tween 200 and 250° F'., a concentration of an
temperature of about 190° F. at the time of treat- .
- hydride from 3 to 10%,
v ment, the solvent should have a boiling point of
desirably at least 5%
and preferably 7 to 8% by volume, and a treat
at. least 200° F., and_preferably above 220° F.
time of 20 minutes to oneihour or 90 minutes.
Solvents that have been found suitable include 15 ingPreferably
the liquid is introduced at a lower
hydrocarbons having the desired boiling point
temperature, say 185° to 190° F. so that as the
and the halogenated hydrocarbons. For reasons
reaction begins there will be no local overheat
of convenience and safety non-in?ammable sol
ing. As it proceeds and nears the end the tem
vents, suchas halogenated hydrocarbons, are pre
perature may be raised to 200° F. without harm.
ferred. A particularly suitable solvent is per 20 The
higher temperature also provides a larger
chloroethylene or tetraehloroethylene. This has
amount
of latent heat in the fiber to remove the
a boiling point of about 248° F. and permits the
solvent by vaporization when the vacuum
treating operation to be carried on at around
applied.
'
'
185 to 210° F., as may be desired.
The amount of treating liquid of any of the
The temperature of the liquid at the time it 25 compositions
described above that is required in
is introduced to the ?ber and while in contact
relation to the amount of ?ber to be treated may
therewith will depend upon the concentration of
vary over relatively wide ranges. Since all of the
the anhydride and the length of the time it is '
treating liquid is recovered except the anhydride
desired to subject the ?ber to the treatment. I
have discovered that quite high temperatures 30 which enters into chemical combination during
the treatment, it is preferred to use enough to
may be used without harming the ?ber. If for a
thoroughly cover the ?ber during the treatment.
given concentration of the anhydride, a treat
In general, 7 or 8 to 40 parts of the liquid to 1
ment for one-half hour,at 190° to 200° F. is sat
part of the ?ber is preferred. The ?ber gains
isfactory, the time could be reduced to one-half
that, namely, to ?fteen minutes if the tempera. as
ture is raised to 220° F. However, at tempera
‘tures much above 200° ‘F. .there may be some
slight yellowing of the ?ber. This may be un
“
objectionable when the ?ber is to be used for
in weight by about, 3 to 8% following the treat
ment, which is attributed to the anhydride that
combines chemically with it. Thus the amount
of anhydride present during the-treatment is ,
adequate for the purpose.
Inclusion of the proper amount of acid with
some purposes, but if a white fiber is desired the 40
the anhydride is essential.‘ The exact chemical
highest temperature to be used is selected with
role the acid plays is not entirely clear, since the
this consideration in mind. The temperature
acid itself is not capable of acylating the ?ber.
may be reduced :below 190° F. by continuing the
However, I have discovered that anhydrous ?ber.
treatment for a longer period. Treating for the
treatd with acid free anhydrous anhydride is not
lengths of time given does not harm the ?ber.
acylated satisfactorily. The ratio Of'the acid to ‘
but for economic reasons it will be understood
anhydride is preferably about 10 parts of anhy
that there is no advantage in continuing the
dride 'to 1 to 10 parts of acid, preferably‘ 3 to 5
treatment beyond such time as is necessary to
parts
of acid by weight or volume since the
secure the desired results.
densities of the acid and anhydride ‘are so
The temperature could be reduced still further‘ 50 similar.
‘ Thus, a preferred treating liquid might
by employing a higher concentration of the an
contain
8 parts of anhydride, 2.5 parts of acid
hydride in the diluent solvent. For example, if
and 89.5 parts of a solvent, by weight.
\
the solvent contained about 50% anhydride 9.
It is preferred that the ?ber should be as free Q
lower temperature of approximately 150° F. could
from water as possible at the time of treatment,
be used and the time of treatment reduced to a
very few minutes. The use of larger quantities
of anhydride, however, is not as economic as the
use of a smaller quantity at a higher tempera
ture, nor is the control as accurate.
i
’ since any water contained in the ‘fiber reacts with
the anhydride to form acetic acid and und_esir--v
ably increases the ratio of acid to anhydride in
the treating liquid and uses up a portion. of the
However, it may be uneconomic un
In the above discussion the amounts given are 60 anhydride.
der some circumstances to dry the ?ber to a
by weight using perchloroethylene as the diluent.
completely anhydrous state before treatment,
If a lighter diluent is used suitable adjustment
and the dry appearing ?ber may usually contain
must be made.
up to 10% moisture. Furthermore it may be
From the above it will be seen that the rate
of the reaction is dependent upon temperature 65 diiiicult to dry the formaldehyde treated ?ber to
a moisture content below 11/2% without harming
and concentration of anhydride. Since the re
it. The-extent tov which the ?ber is dried will
action is exothermic the rate must not be so
depend upon the economics involved. Thus, it
high as to produce local overheating. The rate
may be more expensive to reducethe moisture
is adjusted so that the heat developed by the
the ?ber below a given amount than it is to
reaction can be absorbed by the liquid and thus 70 Lin
utilize a part of the anhydride byreaction with‘
the ?ber prevented from- yellowing by subject
the water. Under present circumstances it is
tion to too' high a temperature.
desirable to reduce the moisture to not over 2%.
The relation of the treating temperature. the
concentration of anhydride, and the length of
In view of this circumstance the ratio of acid '
to anhydride in the treating liquid before it is
treatment also involve economic factors, includ 75 introduced into the treating centrifuge should be
2,408,026
': '11
line 34 may be closed and the acetate removed '
adjusted in view of the moisture content of the
‘from the centrifuge basket. The acetate may be
?ber. Thus, if the ?ber contains moisture the ‘ reconverted into acetic anhydride by known
amount of anhydride in the liquid should be in
chemical methods, so that. there is no loss be
creased and the amount of acid decreased below
cause of moisture in the ?ber.
introduction
of
_
the preferred ratio, so that upon
The various materials condensed in the con
the liquid into the centrifuge and reaction of an- , _ denser 28, including watenacid, anhydride‘and
hydride with the moisture in the ?ber, the
diluent solvent. are passed to the receiver II.
.amounts of anhydride and acid remaining'in the
These materials stratify into an upper layer of
liquid will be those preferred. This, of course.
10' water and a lowenlayer of diluent. Apparently ‘
involves simple chemical calculations.
the anhydride and the acid are more soluble
After each treatment of moisture containing ', both
in the solvent than in water and the lower
?ber the anhydride and acid content of the treat
strata, which contains the diluent solvent, anhy
ing liquid is altered. It is necessary, therefore, dride and acid may be pumped backinto the’
to correct the composition of the liquid in the
supply tank.
will
supply tank before the next batch of fiber is
From the above description it will be apparent
that my process appears to be applicable most‘
Since a portion of anhydride is used up in each
readily to a batch operation, but it may also be
treatment both by combination with the ?ber and
applied to a continuous process. For example,
by reaction with any water in the ?ber, it is
the
?ber in continuous strands or ropes may be
necessary to add anhydride to the supply tank, 20 drawn through pipes or tubes through which
ypreferably after the treatment of each batch, so
the treating liquid is ?owing preferably counter
that the anhydride concentration will be correct.
currently.
’
'
Since the amount of acid in the treating liquid
The ?ber, at the time it is introduced into the‘
will constantly increase upon reusing it if the
centrifuge, may be in a tow of continuous ?la
?ber contains moisture, it is necessary to remove
ments, or it may be cut into staple form. In‘
a portion of the acid, preferably'after the treat
‘ the latter form the staples will be free to take
treated.
-
_
'
ment of each batch of ?ber. This is done most
on or relax into any position and thus can ac
readily by neutralizing the acid and removing it
as a salt.
-
'
Rather than treat all of the liquid so as to re
so
duce the amount of acid to the desired point, I
‘ ?nd it convenient to completely neutralize all
of the acid in a portion of the liquid, the amount
quire a crimp which will be permanent, since
the new chemical compound will be formed while
the ?ber is delineated in the crimped position.
I have described my invention primarily with
reference to treatment by acetic anhydride‘ and
acetic acid. As I have mentioned previously, the
~of liquid so neutralized being such that upon its' , anhydrides' of other acids and other free acids
return to the entire volume of liquid the acid 35
ratio will be correct. This is accomplished read
ily
' Afterthe
as follows:liquid ha
been returned from the. .
may be used. The anhydride may be of the same
acid that is present‘ in free form or of a different ‘
acid. Generally when a different combination‘
of acid and anhydride is employed, it is prefer
centrifuge I by the pump I! to the supply tank
able to utilize acetic or lactic acid as the acid
ill, a sample is withdrawn and analyzed for an 40 since these acids are desirable because of their
hydride and'acid content. Su?lcient anhydride
swelling action on the ?ber and the consequent
is then added to raise the anhydride concentra
increase in speed of reaction. The combina
tion to, the desired amount. From simple calcu
tion, for example, of acetic acid with malic or
lations it is possibleto determine what fraction
maleic anhydride products a very soft ?ber simi
of the total volume of liquid can have all of the .45 lar to camel's hair. Lactic anhydride and lactic
acid removed therefrom so that the entire vol
acid give admirable results. A mixture of acetic
ume of liquid will have the desired amount of
acid and stearic anhydride or any other high
acid. After this calculation is made, the calcu
molecular. weight anhydride produces an un
lated'amount of liquid is withdrawn through the
usually soft fiber; 'The lubricating properties of
pipe 2| by opening the valve 22 and admitting 60 the high molecular weight fatty acid can be read
the ‘calculated amount of liquid into the treating
ily noticed in the ?nished ?ber, but it has the
chamber ill.
To this is added soda ash or a
caustic which neutralizes the acid. Preferably
' the temperature at the time of neutralization is
advantage that the high molecular weight sof
tening fatty material is combined chemically
with the ?ber. In some instances the anhydride
/200° F. or above and the liquid may be heated 65 may be formed at the time of the treatment. For
’ water formed upon neutralization is readily re
in the treating chamber by steam coils. The
water formed upon neutralization is readily re
example. acetic anhydride and stearic acid will
form stearic anhydride and acetic acid and the
action may be the combined acylating actions of
moved by means of the vacuum pump 30a so
stearic and acetic anhydrides.
that it is not available to decompose thev an 60
I have indicated heretofore that the protein,
hydride in the liquid. when soda ash is used
to neutralize the acid, the water is vaporized and
goes off with the carbon dioxide. The liquid is
then admitted to the centrifuge I! by the pipe
I90 and valve Mb. The basket within the cen
trifuge is preferably lined with canvas or a ?lter
formaldehyde and anhydride combine to form’ a
new chemical compound. The exact reactions
are difficult to describe because of the complex
nature of protein, particularly casein. My in
65 vestigation led me to believe that the reaction of
thevformaidehyde and the anhydride with the
ing material. The salt formed by the neutraliza
protein is one involving the amino groups of the
tion is retained within the basket and by rotat
protein. Benedicenti has suggested that the re
ing the basket of the centrifuge, it is possible to
eliminate substantially all of the liquid from the 70 action between casein and formaldehyde is some
what as follows:
- _
salt.
At the same time the acid-free liquid is
pumped from the centrifuge by means of the
pump 23 and returned to the supply tank by
means of the pipe 25. After all of the liquid
has been returned to the supply tank, the vacuum 76.
2,408,026
13
14
where R is the casein residue. The fact that the
formaldehyde can apparently be removed read.»
ily from the formaldehyde-casein complex
small. In the case of acetic acid this will be
. a pH of 3.5. to 4.
the above type.
v
.
'
manuacture of felt hats from the ?ber.
'
Upon treatment of the casein-formaldehyde
complex with the acylating agent it is probable‘
This is very desirable, since a
?ber having this pH is'particularly desired’ in the -
seems to be suggestive that the reaction is of
I
.
In the event that the pH value of the fiber is
to'be raised, this can be done by ‘treating the
?ber with a buffered. neutralizing agent, such as
' disodium hydrogen phosphate and washing to re
move the phosphate, and any other salts formed.
that a reaction of the following nature takes
place: R—-NH—CH2-—OOCR1, where R1 is the
residue of the acylating anhydride, i. e., CH: in 10 By adjusting the concentration of the'neutraliz
the case of acetic anhydride. ‘_
'
ing solution and the time of treatment, the re
The exact chemistry involved
must at best be . sulting
’
?ber may be given any pH value desired.
a matter of speculation, since the complexity of , ‘
A
pH
value
of Mo 6 is desired by the textile: trade,
the matter does not permit a de?nite determina
and a. low free acid, preferably less than. 1.0%.
At any stage of the treating operations the ?ber
That the reaction is one in which the form
may
be treated with a softening agent, prefer
aldehyde combines with the amino groups ‘and v ably a cationic active compound such as “Ah-‘
the anhydride then combines with this combina
covel” which does not have any eifect upon
tion is indicated by the fact that the carboxyl
the pH value of the ?ber. .
groups probably remain unaltered in the protein 20
My invention can be the subject of many variar
tion.‘
.
‘
I
-
molecule. My new ?ber has an acid number as
does casein which indicates that there are prob
tions as is indicated herein, and can use many
' equivalent materials all of which are to be in
- eluded as indicated in the following claims.
ably some unaltered carboxyl groups. However,
the carboxyl groups apparently-do not contribute
to any undesirable properties of the ?ber.
I
That my new product is the reaction of pro
This application is a continuation-in-part of
25 my applications Serial No. 242,279, ?led November
tein, formaldehyde and the anhydride is shown
25, 1938; Serial No. 291,616, led August 23, 1939,
and Serial No. 309,028, ?led December 13, 1939.
by the fact that the treatment of casein ?ber
I claim:
“
with an anhydride, which ?ber has not previously‘
A method of improving the dyeing proper
has a formaldehyde treatment, does not pro 30 ties1. of
a “synthetic protein-base material formed
duce my new ?ber. Apparently in such a treat
by shaping an alkali-soluble acid-coagulable pro
ment the anhydride combines with groups in “the
tein comprising casein and treating it with form
protein to form linkages which are hydrolyzable.
aldehyde,
which comprises subjecting said pro
As further indicative of the fact that the
tein-base
material
to a treating liquid at a tem
amino groups are blocked, my new ?ber is not
perature above 150° F., said treating liquid com
amphoteric as are ordinary proteins in that it
prising an inert diluent'in which is dissolved from
does not possess an isoelectric point characteristic
3 to 50% of the anhydride of a carboxylic acid
of protein.
in admixture with 1 to 10 parts of a free carThat the ?ber produced in accordance'with
boxylic acid for each 10 parts of theanhydride.
my invention is ‘entirely vdifferent is indicated
‘\2\. A method of improving the dyeing properties
> by-the fact that it will withstand vigorous boil
of a synthetic casein-base ?ber formed by shaping
ing for two hours in neutral distilled water with
'said casein/into ?ber form and treating it with
out any substantial deleterious effect, and upon
formaldehyde, which comprises subjecting said
removal from this boiling water treatment and
?ber to a treating liquid at a temperature above
drying by usual methods the ?ber will retain sub
stantially all of its original qualities which ren 45 150° F., said treating liquid comprising an inert
diluent in which is dissolved from 3 to 50% of
der it suitable as a ?ber. It will :be appreciated
an anhydride of acetic acid in admixture with 1
that this is a very vigorous test and that there
to 10 parts of acetic acid for each ‘10 parts of ‘the
are even few naturally occurring proteinaceous
anhydride.
'
?bers which‘ will withstand such a test.
3. A method of improving the dyeing proper
Fiber produced in accordance with my invention 50
ties of a synthetic casein-base ?ber formed by
will also pass the so-called "pepsin test" (Mel
shaping said casein into ?ber form and treating
liand Textilber. 20, 697-8 (1939)). This is one
'of the most rigorous tests to which this type of , it with formaldehyde,which comprises subject
ing said ?ber to a treating liquid at a temperature
proteinaceous ?ber can be subjected and that
of
150° to 220°, F. for from 15 to 90 minutes, said
55
my ?ber is not attacked by the pepsin in this test
treating liquid comprising an inert diluent in
indicates that it is no longer a pure protein ma
which is dissolved 3 to 10% of acetic anhydride
terial.
and 1 to 10 parts of acetic acid for each 10 parts
As further indicative of the novelty of my in
of the anhydride.
vention I might mention that the treatment of
4. A method of improving the dyeing proper
casein ?bers as proposed heretofore in the art, 60
ties
of a synthetic casein-base ?ber formed by
such as by treatment with nitrous acid or a treat
shaping said casein into ?ber form and treating
ment with halides, does not result in a ?ber which
it with formaldehyde, which comprises subjecting
will withstand the above described "boil test" ,or
said ?ber to a treating liquid for from 15 to 90
"pepsin test."
minutes at a temperature of fromv 150° to 220°
The ?ber after being removed from the cen 65 F., said treating liquid comprising a volatile inert
trifuge at the end of the treatment may be ,washed
diluent containing at least 5% and less than 60%
to remove free acid, since it is more or less per
acetic anhydride and 1 to 10 parts of acetic: acid
meated by the free acid in the treating liquid.
for each 10 parts of acetic anhydride, then cen
The water dissolves a substantial proportion of
trifuging the ?ber after the treatment to remove
70
the acid. However, it is impossible as a practical
the major portion of thetreating liquid adhering
matter to dissolve all of the acid and the ?ber.
to the ?ber, and evaporating still an additional
is left with a resulting pH value characteristic ' amount of the remaining adhering treating liquid
ofv the free acid used, irrespective of the amount
by placing the ?ber under a vacuum.
of acid retained, even though this be extremely 75
FRANCIS CLARKE ATWOOD. ‘
'
7
.
'
l5
l6 -
.
Certi?cate-of Correction
’ September 24, 1946;
Patent No. 2,408,026.
"
'
>
’
,
~
-
'
l
'
FRANCIS CLARKE ATWOOD
, It is hereby certi?ed that errors appear in the printed speci?cation of the above
numbered patent requiring correction as follows: Column 10, line 9 after “tempera
ture” insert of; column 11, line 56, strike out the'words and syllable “water formed
upon neutralization is readily re-”; column 12, line 45, for “products” read ro'duces;
column 13, line 30, for “has” read had; and that the said Letters Patent 5 ould be
read with these corrections therein that the same may conform to the record of the
case in the Patent O?ice.
'
.
‘
Signed and sealed this‘26th day of November, A. D. 1946;
it
LESLIE FRAZER,
First Assistant Oonvmz'ssimwr of Patents.
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