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Патент USA US2406905

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2,406,905
Patented Sept. 3, 1946
UNITED STATES PATENT OFFICE‘
,
2,406,905
METHOD FOR PRODUCING CELLULOSIC
.
STRUCTURES
Henry Shirley Rothrock, Wilmington, DeL, as- '
signor to E. I. du Pont de Nemours & Company,
Wilmington, Del., a corporation of Delaware
No Drawing. Application May 6, 1941,
Serial No. 392,116
2 Claims. (01. 117-145)
2
I
may be otherwise advantageously wrapped in
such transparent tissue.
It is, therefore, an object of this invention to
This invention relates to regenerated cellulose
structures, especially those of pellicular nature.
More particularly, it relates‘ to a method for pro
provide a new and useful method for producing
ducing ?exible and durable regenerated cellulose
pellicles by treating the same with a softening
agent comprising a synthetic linear polymeric
softened regenerated cellulose materials possess
ing desirable physical properties.
It is a further object to provide regenerated
cellulose materials having a softening agent
associated therewith which softening agent will
application, Serial No. 392,115, filed of even date
10 not tend to escape through volatilizatlon or
through transfer to other celluloslc bodies.
It has been found that glycerol, ethylene glycol
Other objects of the invention will appear
and other agents such as formamide, diethylene
hereinafter.
'
glycol, and the like used heretofore for the soften
The objects of this invention may be accom
ing of regenerated cellulose products have pos
sessed two serious'dlsadvantages; namely, vola 15 plished by incorporating, as a softening agent, in
compound.
This application is related to my copending
'
4
herewith.
a regenerated cellulose sheet or ?lm, a water
tility and a tendency to transfer or migrate to'
other materials in contact with the softened re
soluble synthetic linear polymer having a molecu
lar weight above 400 and a boiling point of at
generated cellulose. Since thesoftening action
least 170° C. at a pressure of 1 millimeter of
is highly critical, it is essential that the precise
.
concentration of a given softener within the cellu 20 mercury.
A. wide variety of polymeric materials are found
losic body be maintained at a relatively constant
to be useful
this operation. It is a necessary
value. For example, if the concentration of sof
condition that the polymeric materials used in '
tener is too high, the cellulosic films will be un
this invention be suiiiciently water soluble to
tion is too low the article will be brittle and lack 25 permit their introduction into the regenerated
cellulose sheet by means of an aqueous solution.
durability. An effort is therefore made at the
duly limp and sticky, whereas if the concentra
In general, adequate water solubility is insured
time of‘ manufacture to incorporate precisely the
correct amount of softener to obtain the physi
by incorporating in the polymeric compositions
satisfactory softening action isobtained.
compounds.
cal properties desired in the final film. How- ' 30 solubilizing groups separated preferably by one
or two carbon atoms. When the atom chain be
ever, in the case of ‘a pellicle with a large area
tween the solubilizlng groups consists of more
exposed to the atmosphere for long periods of
than two atoms it may also possess one or more
time, even those softening agents which have a
interruptions by hetero atoms, e. g., 0, N, or
very low but appreciable vapor pressure will in
hetero groups such as $02 and other groups
time escape to a sufficient degree to lower the
concentration in the film below that at which 35 which contribute to water solubility in organic
'
The preferred method of carrying out this proc
Difficulties arising from a decrease in softener
ess consists in passing a regenerated cellulose
content may also be brought about in quite a
different manner from the escape of the softener 40 sheet, after the necessary purifying, bleaching
and washing operations, through an aqueous bath
through volatilization. It has been observed that
containing a prescribed amount of water-soluble
regenerated cellulose products which are in con
polymeric softening agent. After impregnation,
tact with other cellulosic bodies have a tendency
excess solution is removed and the film is dried in
to lose their softening agent when this agent is
of the type represented by glycerol and glycol
45
a suitable manner.
The following examples are given to illustrate
the preferred methods of carrying out the present
invention. The parts and percentages referred
ucts such as paper, cotton, linen fabric, etc.,
to are parts and percentages by weight.
wrapped in thin pellicles of regenerated cellulose
Example I
softened with glycerol are found after a short 50
time to extract a large portion of the glycerol
‘Viscose is extruded into a bath comprising sul
from the pellicle used as a wrapping tissue, leav
furic acid and sodium sulfate to effect a coagu
ing' the latter brittle and. absorbent. This is a
lation and/or regeneration of the viscose to a self
serious restriction in the use of these materials
sustaining ?lm. This film is then desulfured,
for wrapping a large number of products which 55 bleached, and washed according to Brandenberg- '
and, in fact, most of the softening agents here
tofore known.
As an example, cellulosic prod
2,406,905
4
or United States Letters Patent No. 1,548,864.
Before drying, the sheet of gel regenerated cel
tion of the catalyst and removal of unreacted gly
col formal.
lulose is immersed in or drawn through an aque
ous bath maintained at a temperature of 30° C.
Example V
ly long to thoroughly impregnate the gel struc
weight of approximately 1316. The ?lm produced
Film prepared as in Example I is passed
and containing 11% of glycol polyformal having 5
through an aqueous bath containing 11% of cetyl
a molecular weight of approximately 440. The
alcohol-glycol polyformal having a molecular
film remains in contact with this bath su?icient
after removal of excess solution and drying in
ture‘ with the solution. after which it emerges
from the bath, excess liquid is removed from the 10 the usual manner is transparent, ?exible and
maintains its durability in contact with other cel
surface thereof by means of squeeze rolls, doctor
lulosic materials such as cloth and paper.
knives, etc.,v and the ?lm dried on the conven
This polymeric product may be prepared by
tional roll drier. After drying, the ?lm is found
heating at 100° C. for five hours one part by
to contain 20% glycol polyformal, based on the
weight of the cellulose, and approximately 6% 15 weight of cetyl alcohol with 18 parts by weight
of glycol formal in the presence of 0.5% by weight
water. The ?lm so produced is transparent, ?ex
of an anhydrous acidic catalyst after which the
ible, and durable. The loss of softening agent
catalyst is neutralized and unreacted glycol for
through volatilization or migration to other cel
mal is removed.
lulosic bodies such as paper and fabric is only
Example VI
one-tenth as great as that shown in correspond 20
ing glycerol softened ?lms.
Film produced as in Example I is immersed in
, The glycol polyformal is prepared by heating
an aqueous bath containing 15% of glycol digly
monomeric glycol formal at 160° C. for a period
colate polyester prepared through the action of_
of five hours in the presence of a catalytic amount
one part by weight of diglycolic acid with approx
of concentrated sulfuric acid. The acidic cata
imately one and two-tenths parts by weight of
lyst is neutralized, unreacted monomer is re
ethylene glycol under the in?uence of an acidic
moved and the product extracted with a suitable
catalyst. Excess solution is removed from the
solvent or used directly.
surface of the ?lm and the same dried in the
usual manner. The pellicle so produced contains
Example If
30 23% of the softening agent and is ?exible, trans
The ?lm prepared as in Example I is passed
parent and durable.
through a bath containing 7% glycol polyformal
Example VII
having a molecular weight of approximately 710
, and prepared as in the preceding example. Ex
Film prepared as in Example I is suspended
cess solution is removed from the surface of the 35 in a bath containing 7% of polyethylenimine
web, and the same dried in the conventional type
synthesized through the action of a polymeriza
of roll drier. Films so produced are found to have
_tion promoting acid catalyst on ethylenlmine ac
a softener content of 12% based on the weight
cording to British Patent No. 461,354. After heat
of the cellulose, and a moisture content of 6%.
ing at 100° C. for 20 hours, the film is washed
This ?lm ‘is transparent, highly ?exible, durable,
with cold water, with alcohol, and the same dried
and shows practically no loss of softening agent
in vacuo at 100° C. The film so produced con
, ‘when in contact with cellulosicxmaterials such as
paper and fabric. I
" Example III
Film produced as in Example I is passed
through a bath containing 11% of glycol poly
formalof molecular weight 1284, prepared in the
general manner described in Example I. The ex_
cess solution is removed from the surface of the
45
.taining 5.31% nitrogen is soft and durable and
shows good receptivity to various dyeing agents.
Example VIII
Film prepared as in Example I is immersed
in a bath containing 11% of polyethylene oxide
(C'arbowax 1500).
Excess solution is removed from the surface of
the web, and the same dried in the conventional
film, and the‘ same dried in the customary man 50 type
of roll drier. Film so produced is found to
ner. The ?nal product contains 20% of the sof
have a softener content of 17 %, based on the
tening agent, istransparent and soft and main
weight of the cellulose, and a moisture content
tains its high ?exibility and durability when in
6%. This film is transparent, highly ?exible,
contact with other cellulosic bodies.' The loss of 55 of
and durable, and shows no loss of softening agent
softening agent by volatilization and migration
in contact with cellulosic materials. such as paper
to other cellulosic materials is lessthan one-tenth
and fabric. The polyethylene oxide may be syn
that exhibited .by glycerol softened ?lms.
Example IV
Film produced as in Example I is passed into
a bath containing an 11% solution of stearic acid
thesized, for example. by heating the monomeric
oxide in the presence of a suitable catalyst (pref
60 erably an alkaline catalyst) until a substantial
proportion of polymer is formed, and removing
the unchanged monomer. (Staudinger, Die
glycol polyformal having a molecular weight of
Hochmolekularen Organischen Verblndungen,
approximately 1280. Excess solution is removed 6_ 1932, p. 287, et. seq.)
from the surface of the web by means of squeeze 0
Example IX
rolls andthe product-dried in the usual manner.
The ?lm so produced contains 8% of softening
Film prepared as in Example I is passed through
agent, is transparent and shows no loss of softener
a bath containing 11% of a reaction product of
by volatilization or by migration to other cellu
ethanolformamide and ethylene oxide described
losic bodies. '
p
.
70 in the following paragraph having an average
The polymeric material is prepared'by heating
molecular weight of 469. Excess solution is re
one part by weight of stearic acid with 10 parts
moved from the surface of the film and dried in
by weight of glycol formal in the presence of 0.1%
the conventional manner. The ?lm so produced
to 0.5% by weight of an anhydrous acidic catalyst
contains 17% of the softening agent, is trans
for a period of 5 hours, followed by neutraliza 75 parent and highly ?exible and shows no loss of
2,406,905
softener either by volatilization or by migration.
The above softening agent may be prepared
by passing ethylene oxide into ethanolformamide
pending application Serial No. 350,108, ?led Au
gust 2, 1940, by mixing equivalent quantities of
adiponitrile dimethyl diimino ether dihydrochlo
Example X
Example XV
ride and hexamethylenediamine in methanol and
at a temperature above 100° C. and under the in
?uence of an alkaline catalyst until the desired 5 allowing to stand at room temperature for 48
hours.
'
molecular weight has been attained.
Film prepared as in Example I is immersed for
Film prepared as in Example I is suspended
for 10 minutes in a bath containing 10% of poly 10 one hour in an aqueous bath containing 15% of
a polymeric urea described in the following par
meric quaternary ammonium bromide described
below. Excess solution is removed from the sur- 7 agraph. After removal of excess solution and
drying the film is found to retain the softening
face of the ?lm and the same dried in the con
agent permanently. ‘
ventional manner. A clear film is so produced
The polymeric urea is prepared by heating
equivalent amounts by weight of butyldiethanol
which retains the softening agent permanently.
The polymeric quaternary ammonium compound
may be prepared by heating N,N,N',N'-tetra
amine and bis-N,N’-methoxymethyl-urea at ap
proximately 100° C. for a period of 3 to 4 hours.
The polymer so produced is solubilized by treat
20 ing with an equivalent amount of a mineral acid
_ methyl decamethylenediamine and p-xylylene
dibromide in methanol for a period of 42 hours.
Example XI 4
such as hydrochloric acid.
‘
Example xv:
Film produced as in Example I is immersed
in an aqueous bath'containing 20% of polyvinyl
alcohol having a molecular weight of about 3600
The ?lm prepared as in Example I is immersed
for one hour in an aqueous bath containing ap
and containing approximately 20% of polyvinyl 25 proximately 5% of polymeric sulfonium salt de
acetate during a period of one hour. Excess so
scribed below. - After the ?lm has been soaked
lution is removed from the surface of the web
for one hour excess aqueous solution is removed
and the film dried on the conventional roll drier.
and the film dried. The ?lm so produced re
After drying the film is- found to contain 10% of
the softening agent. A transparent ?lm is so 30 tains the softening agent when in contact with
other cellulosic materials such as paper and tex
produced which permanently retains the soften
tiles.
ing agent.
'
The sulfonium compound is prepared as de
The polyvinyl alcohol is prepared by heating
scribed in copending application Serial‘ No.
monomeric vinyl acetate in toluene at 100° C.
319,791, ?led February 19, 1940, by dissolving
in the presence of 1% of benzoyl peroxide to yield 35 polyhexamethylene
sul?de in toluene at re?ux
polyvinyl acetate, (Starkweather and-Taylor, J.
temperature followed by addition of a slight ex
Am. Chem. Soc. 52, 4708 (1930)), from which ' cess of dimethyl sulfate. Heating is discontinued
the polyvinyl alcohol is obtained by hydrolysis.
(as soon as dimethyl sulfate is added since the
’
Example XII‘
'40 heat evolved is sufficient to maintain reaction. -
When the spontaneous reaction has subsided ex
cess dimethyl sulfate is destroyed by addition of
alkali solution and the product is‘ made up in
aqueous solution.
The ?lm prepared as in Example I is immersed
for one hour in an aqueous bath containing 10%
of polyvinyl alcohol of molecular weight 3600
containing approximately 2%. polyvinyl acetate,
and prepared as in the preceding example. Exe 45
Example X VII
cess solution is removed from the surface of the
web and the ?lm dried in the conventional type of
roll drier. Films so produced are found to have
a softener content of 4%, which is retained when
the films are in'contact with other ceilulosic ma
Film_ prepared as in Example, I is immersed
for one hour in an aqueous bath containing 15%
of a polymeric acid material, the preparation of
which is outlined in the next paragraph. The
film produced after drying is transparent and
terials such as paper .or textiles.
does not lose its durability when in contact with
paper, textiles, or cotton.
Example XIII
The film prepared as in Example I is immersed
The polymeric acid may be prepared by heat
ing in a bomb at 150° C., 1200 grams of maleic
for one hour in an aqueous bath containing 10% 55 anhydride, 1500 grams of ethylene, and 40 grams
of polyvinyl alcohol having a molecularweight of
of benzoyl peroxide in 6 liters of xylene. The
about 12,000, containing approximately 20%
product is washed with benzene and ether and
polyvinyl acetate and prepared as in the preced
then made up in the required aqueous solution
" ing examples. Excess solution is removed from
by dissolving in an equivalent amount of alkaline
the film and the same dried in the usual man 60 solution.
ner. A transparent film was produced contain
Example XVIII
ing 5% of the softening agent which was retained
in the ?lm in contact with other ceilulosic mate
rials such as textiles and paper.
Example XIV
The film prepared as in Example I is immersed '
Film produced as in Example I is immersed for
one hour in an aqueous bath containing 15% of
65 a polymeric phosphate described below. Excess
solution was removed from the ?lm and the same
was dried in the customary manner. A perma
nently impregnated film is produced.
‘
for one and one-half hours in an aqueous bath
The polymeric phosphate .‘ is prepared by allow
described below. Excess solution was removed 70 ing equalparts by weight of ethylene glycol and
phosphorus oxychloride to react spontaneously
from the film and the same was dried in the con
containing 10% of a polyamidine hydrochloride
followed by heating for 4 hours.
ventional type of drier. A transparent film was
produced which retained the softening agent
even in contact with other ceilulosic materials.
The polymer was prepared as described in co
2
75
Example XIX
'
_
Film produced as in Example Iis immersed
2,406,906
for one hour in a bath containing 15% of poly
phosphonamide at a temperature of 30° C. After
removal of excess solution and drying the ?lm
is found to retain the softening agent when in
contactvwith other materials such as textiles or
paper.
'
Imlnoethera:
I?!
.
The polyphosphonamide is prepared by heating .
one part of phosphoric acid with 1.15 parts of
hexamethylenediamine for one hour at‘ 230°
'
260° C.
10
Example XX
Film prepared as in Example I is immersed
for one hour in an aqueous bath containing 5%
of glycerol and 15% of polyethylene oxide pre
pared as in Example VIII. Excess solution is 15
removed from the ?lm by means of squeeze rolls
and the film dried in the conventional type of
roll drier. The ?lm so produced is flexible, trans
parent, and durable.
20
Example XXI
A regenerated cellulose pellicle in the form of
a tube is coagulated, regenerated, and puri?ed
in a manner similar to that for ?lm and is then
passed through a bath containing 11% of the 25
l5.
Acids:
Phosphonamides: (
reaction product of methyl Cellosolve and ethyl
0
ene oxide, prepared in the same manner as de
scribed in Example IX, said reaction product
having an average molecular weight of approxi
Phosphates:
sure and the upper portion of the neck of the
Ethers:
bottle. This cellulosic band is in contact with
the paper, liquor stamp with which such bottles
Sulionic acids:
mately 783. Excess liquid is removed from the 30
surface of the tube, the same cut into short
lengths and applied to the mouth and neck of a
liquor bottle as a secondary closure. Upon evap
oration of the moisture, the band shrinks into
intimate contact with the neck of the bottle, 35
serving to protect the cork or other primary clo-v
are provided.
It is found that even after long 40
periods of storage, the softening material does
not transfer from the cellulosic band to the pa
per of the tax stamp, and hence the cellulosic
band is not embrittled or otherwise deleteriously as Ch
affected so as to cause its premature removal from
the bottle.
All of the examples given have been set forth
in which R and R’ are divalent organic radicals,
preferably containing one or two carbon'atoms
which may be alike or different; R2 and Rsare
either hydrogen or monovalent hydrocarbon radi
cals; X is an acidic radical such as halogen; and
n is a number su?lciently high so that the molecu
lar weight of the polymer is above 400. It may
in terms of a sheet or ?lm of gel regenerated cel
be desirable to incorporate in the atom chain
lulose (gel regenerated cellulose is a water swollen 50 other hetero atoms or groups such as O, N or SO:
regenerated cellulose which never has been
as exempli?ed in the case of polymeric triglycol
dried). Obviously this is the more practical way
of practicing the invention since the softening
adipamide,
'
0
- agent is customarily incorporated into the sheet
.
(-—C 0 (CH9) 4—(L)—-_NH—CH:CH:O OHsCHiO CHlOHiNH-')n
or‘ ?lm while the latter is in the gel state in and
during the normal courseof manufacture. Obvi
or glycol diglycolate polyester,
ously, if one desires to impregnate an already
dried regenerated cellulose ?lm with a softener
of the character described, it is possible to rewet
the dried ?lm so as to render it highly swollen 60 An example of synthetic linear polymer which is
illustrative of the general type of polymeric mate
whereupon it may be treated with treating baths
rials
useful in this process is polyvinyl alcohol,
similar to those described, but of composition
suitable to obtaining the ?nal product desired.
R-(cm-cnon-cm-onon-cH,-—0BoH-).—R
As the water-soluble synthetic linear polymeric
It is seen that the group (—CHOH—) recurs in
softening agents suitable for use in accordance 65 a linear manner to yield a long chain polymeric
compound.
with the present invention, the polymers of the
following recurring units are representative:
The presence of the OH groups on
alternate carbon atoms in the chain insures suf
?cient water solubility for the purpose of this
process.
70
Depending upon the type of ?lm desired, vari
ous modi?ed polymeric materials may be em
ployed such as the products obtainable through
the reaction of a monomeric alkylene oxide or
glycol formal. with such active hydrogen com
75 pounds as acids, amines, amides and alcohols as
2,406,905
typified by glycerol, ethanolamine or formamlde.
It is possible andin some cases even desirable
to employ as softening compositions mixtures
either of one polymer with another or of a poly
meric with a monomeric softening agent. As
typical examples of these mixtures one may cite
mixtures of polyvinyl alcohol with polyethylene
oxide, polyethylene oxide with glycerol or urea,
and glycol polyformal with glycerol.
As above stated, the- polymeric softeners of 10
the present invention should have a molecular
10
which they remain in a non-?brous cellulosic
structure. Since they are of very low volatility,
they are not lost through volatilization, such as a
number of well-known softeners, e. g., ethylenev
glycol and glycerol. Furthermore, they do not
migrate or transfer out of the transparent cellu
lose structure to other cellulosic structures with
which the film may be in contact. This last
named property permits use of these materials
in the form of thin sheets as wrappings with cel
lulosic materials, e. g., fabrics, textiles, paper, etc.,
and permits their long and continued contact
with the contents of the package without losing
the softening agent and, consequently, with the
is essential also that the polymeric products have
a water solubility at a temperature of 25° C. of 15 retention of the ?exibility and durability of the
original wrapping tissue. As another example,
at least 4% in order that they may be introduced
weight above 400', and a boiling point above 170°
C. at a pressure of 1 millimeter of mercury. It
caps and bands used as secondary closures for
containers may be applied to the mouths and
necks of bottles over paper labels and still exhibit
The preferred concentrations of softener in
aqueous bath may ‘range from 4% to 15%, 20 no tendency to embrittlement, splitting, and
cracking after long periods of storage.
although in some cases higher concentrations
in a satisfactory manner into regenerated cel
lulose.
.
Since it is obvious that many changes and
modi?cations can be made in the above-described
details without departing from the nature and
Likewise, the time of immersion may be varied
from a few seconds to an hour or more depending 25. spirit of the invention, it is to be understood that
the invention is not to be limited to the details
upon the rapidity with which the particular poly
described herein except as set forth in the ap
mer is impregnated into the regenerated cellu
pended claims.
lose. The temperature of the aqueous bath may
I claim:
be conveniently maintained at 25°-30° 0. although
in some cases a higher temperature may be de 30' 1. The process which comprises passing a ?ex
ible regenerated cellulose pellicle in a highly swol
sirable. After the regenerated cellulose sheet or
may be required to insure adequate impregnation
of softening agent in . the cellulosic structure.
?lm is dried it should, for normal uses, contain
from 8% to 25% of softener based on the weight
len condition through an aqueous bath contain
ing, dissolved therein, between 4% and 15% of a
of the dry ?lm.
synthetic linear polymer having a molecular
If a colored cellulosic ?lm is desired, it may 35 weight above 400 and a boiling point of at least
170° C. at a pressure of 1 millimeter of mercury,
be obtained in any of the ways commonly known
in the art, including the passage of the sheet or
said pellicle being maintained in contact with the
?lm through a bath containing a suitable dye
stuff. If desired, the dyestuff may be added to
bath liquid for a suf?cient period of time to im
pregnate the same with from 8% to 25% of said
the bath used for introducing the softening agent. 40
polymer.
In the same way, after the ?lm has been treated
'
2. The process which' comprises passing a re
generated cellulose pellicle, in the gel state,
through an aqueous bath, containing, dissolved
therein, between 4% and 15% of a synthetic linear
given to cellulosic pellicles of the type described,‘ 45 polymer having a molecular weight above 400
with softening agent, it may be subjected to any
of the customary after-treatments, such as sizing
or coating or the like which may be customarily
in just the same manner that a glycerol softened
regenerated cellulose ?lm, for example, may be
treated.
'
and a boiling point of at least 170° C. at a pres
sure of 1 millimeter of mercury, said pellicle be
ing maintained in contact with the bath liquid for
a sumcient period of time to impregnate the same
The outstanding advantage of the polymeric
softening agents of this invention over those de 50 with from 8% to 25% of said polymer.
scribed in the prior art is the permanence with
'
HENRY SHIRLEY ROTHROCK.
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