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Патент USA US2134172

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Oct. 25, 1938.
Filed March 20, 1937
2 Shee'ts-Sheet l
Oct. '25, 1938.
Filed March 20, 1937
2 Sheets-Sheet 2
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‘Patented 0a. 25, 1938
maas'rns roa MANUFACTURING nnssaa
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William C. Calvert, Chicago, IlL, assignor, to
Wingfoot Corporation, Wilmington, Del.,acor-
poration of Delaware
Application March 20, 1937, Serial No. 132,188
40lalms. (CI. 18-15)
invention relates to apparatus for the >
The invention will be-further explained in con
manufacture of a substantially continuous ?lm Junction with the accompanying drawings, where
of rubber hydrohalide from a solution or disper ‘in Figure 1 is an elevation, partly in cross-section,
sion thereof in a low boiling liquid vehicle. More of the ?lm-forming apparatus; Figure 2 is a plan,
5 particularly it relates to apparatus for the pro
also partly‘in cross section, and Figure 3 is a
duction of a thin ?exible transparent film of a detail of a modi?ed form of the apparatus. It is
rubber hydrochloride.
The ?lm is produced by applying the ‘rubber
not intended by the illustrative reference to the
hydrochloride dissolved or otherwise dispersed in
other devices capable of accomplishing the same
10 a liquid vehicle to a suitable surface, as for ex
ample a moving belt or drum, in the form of a
thin layer of liquid and thereafter voiding said
thin layer of its liquid vehicle content, under
' carefully controlled temperature conditions, by a
15 process of evaporation. To effect rapid volatiliza
' tion of the liquid vehicle, without, however, boil
ing it or in any other way permitting the forma
tion of air or other bubbles which would adverse
ly affect the strength and appearance of the ?lm,
20 the solution or other dispersion of the‘ rubber
use of a moving belt to limit the invention thereto,
or similar results being available in lieu thereof,
as may in any given case be desired.
Referring to the drawings, the tank I is for
storage of the cement; that is, the solution of the
rubber hydrochloride in the low boiling solvent.
The cement is supplied through pipe la, prefer- 15
ably by gravity but otherwise if desired, to the
nozzles 2, from which it flows onto the continu
ous belt 3, which passes over and is supported by
cylinders 4- and' 5, of which the latter is driven
by the motor 6. Instead of supplying the cement 20
through a plurality of nozzles in a header. as
or otherwise applied to the belt or drum, where shown, one or two reciprocating nozzles may be
it is allowed to remain until sufficient of the liquid employed to distribute the cement in front of
vehicle has been evaporated to form a ?lm strong the spreader ‘I. The depth of the ?lm II. is con
25 enough to retain its shape without stretching or trolled by the position of the spreader l; the
becoming otherwise distorted when removed from -width, by the position of the guides 8.
hydrochloride is advantageously spread, sprayed
the belt.
It has been found that the ?lm can be removed
from the‘ belt or drum before all of the liquid ve
30 hicle has vaporized and that ‘by doing so the dry
ing is hastened because of the fact that the liquid
vehicle may then evaporate from both surfaces
of the ?lm. The production of the ‘?lm is there
. The length of the belt 3 and the rate at which
it travels will depend upon the nature of the‘ sol
vent employed, the concentration of the cement,
and the temperature maintained within the dry 30
ing chamber 9. The operation should be so regu
lated that when the ?lm II is removed from the
belt 3 as the latter returns over cylinder 4, it has
fore divided advantageously into two manufactur- , su?lcient body to maintain itself without distor
35 ing stages, in the ?rst of which the ?lm is carried
tion as it passes through the second stage of the
by the belt .or drum and in the second of which
it supports its own weight. In general, it is ad
?lm drying operation. . This second stage takes
place in drying chamber ll.
vantageous to evaporate at least about 80% of
After the ?lm is removed from the belt 3 and
enters drying chamber l0, it is carried over and
under rolls l2 and I3 and subjected to the ?nal v40
drying operation. If preferred, instead of em
ploying only two drying chambers, three or more
may be used, in which event the ?lm, after pass
_ the liquid vehicle before removing the ?lm from
40 the‘ belt or drum.'
As the liquid vehicle evaporates from the ?lm,
it tends to form a layer of vapor which clings to
or remains in the neighborhood of the ?lm and
thus retards further evaporation. The rate of
45 vaporization of the liquid vehicle is increased by
circulating air in contact with the ?lm as it dries.
It has been found that by drawing off a part of
the air used in drying and re-circulating it with
in the system, the rate of evaporation may be
50 increased without increasing the air intake or
the load on the condensers employed for recov
ering the liquid vehicle from the exhaust gases.
According to the preferred form of this invention,
such an air re-circulation system is provided in
5:; connection with both drying stages, the air used
in the second drying stage for the ?nal vaporiza
tion of liquid vehicle from the ?lm being em
ployed in the ?rst stage in the removal of the
liquid vehicle from the solution while it is still
so supported by the belt or drum.
ing through the chamber I0, is subjected to fur
ther drying in subsequent drying chambers. The
rolls l2 and I3 are driven by suitable driving
mechanism It operated by the motor IS in such
manner as to relieve the ?lm II from any unde
sired strain during the drying operation.
Instead of passing the ?lm over and under 50
rollers in the drying chamber Ill,v it may be sup
ported by other means. For example, it may be
supported only at the edges and thus held taut
as it passes through the chamber. Clips may be
used for this purpose, which automatically re
lease the ?lm as it leaves the drier. One satis
factory arrangement comprises two endless chains
supported by. gears or shafts which replace the ,
rollers 12 shown ' in the drawings. The gears
should be placed somewhat further apart at the so
entrance to the drying chamber and somewhat
nearer together near the exit to allow for shrink
age of the ?lm during drying. At each link of
each chain a spike 4| such as that indicated in
Fig. 3 is provided on the inner side of the chain
40 and perpendicular to the plane of the chain.
These spikes 4| puncture the ?lm as it enters the
drying chamber and the ?lm is lifted oi! of the
spikes as it leaves the chamber. Rollers may be
rubber cement is applied to the belt 3, a consider
able portion of it is drawn oi! up through the air
duct 3l-by the blowers 32 located in the compart
ment 33. Steam coils 34 or other heating means
are provided to heat the air as it passes through
this blower chamber. The steam, is advantage- -
ously introduced to di?erent sections of the coil
from a header and the amount of steam intro
duced to each section controlled by a valve so that
provided to aid in puncturing the ?lm if neces
the heat supplied may be carefully regulated. 10
sary. The margins of a ?lm so dried may be re
The heated air is returned to the drying chamber
at a point closely adjacent to where the air from
the chamber l0 enters the chamber 2. The heated
moved by trimming the film as it leaves the drier
in order to give an impervious sheet. The trim
mings may be dissolved and added to the cement
15 used in forming a new ?lm so that there is no
Adjacent to the chamber III air re-circulation
apparatus I6 is provided for re-circulating the
air is advantageously returned to the chamber 3
through two or more ducts 35 to insure uniform 15
distribution of the re-circulated air in the air
coming from the drying chamber ll.
As the cement dries and the ?lmforms, the
air used for drying the ?lm. The blower l1 driven amount of vapor given off by the ?lm decreases.
by the motor it blows air into the chamber is, The highest concentration of vapor is found im
which forms the lower half of the re-circulation mediately above the belt 3 as it enters the cham
ber 9. For this reason the vapor takeoif 23, which
apparatus It. It is separated from the upper por
tion of the re-circulation chamber by the baiile 20 connects with the condenser. is so located that it
and is separated from the drying chamber It by removes the air and vapor from the chamber 3
the perforated baille 2|. The perforations serve at a point near where the belt and ?lm enter the
to distribute the re-circulated air throughout the drying chamber 9. The duct 3| which withdraws
length of the chamber and prevent the setting up the air to be re-circulated is somewhat removed
of air currents which would tend to distort the from the vapor take-01f 23 but ordinarily will be
located nearer cylinder 4 than cylinder 5. While
The air used for drying is preferably passed in the solution on the belt is still liquid the rate of
a direction substantially counter-current to the vaporization of the solvent is much higher than
direction of the passage of the ?lm II. It is after it has become plastic. . The duct 3| is there
introduced into the system through the ?lter 22 fore advantageouslyspaced such a distance from
and after being used in the chamber Ill passes the cylinder 4 that ?lm passing under it is in a
to the chamber 9 and then out through the vapor plastic rather than a liquid state.
Although'in the speci?c embodiment shown in
outlet 33 to the condenser 24. The fresh air in
troduced through the ?lter 22 mixes with the the drawings but two drying chambers have been
air in the chamber Iii and is then drawn oil’ shown with a single air re-circulation system for
each, it is to be understood that a larger num
through the blower I1 and returned to the cham
ber of drying chambers may be provided and if
40 ber I0 through the perforated bai?e 2|. Two
shutters 25 and 25 control the ?ow of air to the desired more than one‘air re-circulation system
may be provided in connection with each cham
blower. The air which enters through the shut
ter 25 is heated in passing over the steam coils 21 ber. For example, instead of the single air
and the air entering through the shutter 25 is I re-circulation system shown in connection with
drying chamber 9, the air returned through the
45 not heated. By controlling the position of the
shutters 25 and 26, the amount of air passed over ducts 35 may be taken off from the end of the
steam coils 21 is regulated and the temperature drying chamber 0 below the cylinder 5 and the
air withdrawn through the duct 3! may be re
in the drying chamber III is controlled.
turned to the upper portion of the chamber 3
The ?lm l l as it passes from the drying cham
above the cylinder 5. In this case the duct 3|
ber 9 to the drying chamber l0 carries a low per
centage of volatile solvent. This is vaporized in might be somewhat closer to the cylinder 4 than
the chamber l0 and the ?nished ?lm is then rolled in the case where a single air re-circulation sys
onto the roller 28. The air in the drying cham- ' tem is provided, as shown in the drawings.
The air re-circulation not only hastens the
ber III is therefore charged with a relatively low
percentage of vapor and may advantageously be vaporization‘ of the solvent by causing the re
employed in the removal of solvent from the ?lm moval of the solvent vapors from proximity to
on belt 3. For this purpose, it may pass as shown the ?lm as the solvent evaporates, but the thor
ough circulation of the air throughout each
from the chamber Ill through the connecting pas
sage 29, formed within the shield 250, into the chamber tends to keep the temperature within
each chamber substantially constant and thus
60 chamber 9. It is introduced into the chamber 3
at the point where the ?lm leaves the chamber insures uniform drying. Both chambers are ad
and passes back’ over the belt 3 in a direction vantageously well insulated. Heat supplied by
‘generally counter-current to the direction in the steam coils 21 and 34 compensates for any
which the belt 3 is driven. The chamber 0 is heat lost through radiation and maintains each
chamber at the temperature designed to give ‘most
65 divided into an upper and lower portion by the
baffle 30 which extends from side to side of the e?lcient vaporization.
By this method and using apparatus of this
chamber 9 and extends almost the whole distance
between the two drums 4 and 5, so that the air type. a substantially continuous, transparent ?lm
entering through the passage 29 must travel the may be made from a cement prepared as herein
length of the bottom of the chamber 9 before it after outlined.
Two pounds of plasticized pale crepe rubber
‘passes up to the upper portion.
Before'the air which comes up over the drum are dissolved in 31.3 pounds of benzene, giving a
5 from the bottom of the chamber 8 passes back dispersion of approximately 6% concentration.
The cement is cooled to about 10° C. and hydrogen
to the portion of the drying chamber 9 closely ad
75 Jacent to the spray nozzles 2 through which the chloride gas is bubbled through it, with stirring,
for about six hours or until the increase in weight
of the composition due to the introduction of
hydrogen chloride has been about 1.16 pounds.
The hydrogen chloride and rubber are then al
lowed to react at room temperature until a sample
which has been washed and dried indicates on
analysis 29 to 30.5% of chlorine. Generally this
takes about 20 hours.
The resulting cement is then steam-distilled to
remove the benzene and the greater part of the
uncombined hydrogen chloride. The mass of in
completely saturated rubber hydrochloride is then
broken up on a rubber mill and washed thoroughly
with water and dried in a vacuum at approxi
mately 160° F. It is then dissolved in about 20
parts by weight of chloroform to which an anti
oxidant or other age resister has been added. A
suitable age resister is a mixture of 3% of ditetra
hydro furfuryl amine or dicyclo hexyl amine and
20 11/2 % of hexamethylene tetramine.
Any of these
three compounds used alone prolongs the life of
the ?lm, but mixtures give better results. This
solution is then stored in the tank I and supplied
to the belt through the nozzles 2 at the desired
25 rate. Instead of supplying the cement through
nozzles it may be applied to the belt by brushing,
or, in suitably designed apparatus, by dipping the
belt in the cement, or in any desired manner.
In forming the ?lm the evaporation of solvent.
is carried out at a temperature below 142° F., the
boiling point of the chloroform, until suilicient
solvent has been vaporized to ‘eliminate any
danger of the solution boiling and the ?lm thus
formed is then heated to over 142° F. to insure
removal of all traces-of solvent. If a pressure
above _or below atmospheric is employed the tem
perature is varied accordingly. Using a cement
of the composition above-described and applying
sui?cient of it to the belt to form a rubber hydro
chloride film 1,6000 of an inch thick, if the belt is
50 feet long and the temperature in the drying
chamber 9 is maintained at about 140° F. and if
the belt travels at a speed of 12 feet per minute,
the ?lm, with adequate air re-cirulation, will dry
45 su?iciently in traveling the length of the chamber
9 and back again so that it contains about 10—12%
of solvent. It then can be removed from the belt
and further dried by festooning in the drying
chamber In, in which the temperature is main
60 tained at about 160-180" F.
The cement as ?rst
applied to the belt cannot be subjected to the
latter temperature, as it would cause too rapid
evaporation of the solvent and the production of
imperfections in the ?lm due to bubbling, etc.
55 By the two-stage drying operation herein dis
closed the ?lm is rapidly and thoroughly dried
and I5 minutes after the solution has been applied
to the belt, the ?nished ?lm may be wound on the
roller 28.
A ?lm prepared in this manner is non-tacky
and substantially moisture proof and is resistant
to acids and alkalis.
It is'resilient and is not
damaged by creasing. It may advantageously
be used as a wrapping material and for various
65 other purposes. Instead of chloroform, other sol
vents such as benzene,' carbon tetrachloride,
dichlorethylene, etc. may be used.
This application is in part a continuation of
my application Serial No. 685,724 ?led August
70 18, 1933.
It is of course to be understood that numerous
variations may be made in the apparatus which
constitutes the preferred species of the invention
and in the conditions of operating it, as well as
in the nature of the film thereby produced. It
is intended that the patent shall cover, by suitable
expression in the appended claims, whatever
features of patentable novelty reside in the in
I claim:
1. Apparatus for the production of a trans
parent ?lm of a rubber hydrochloride which com
prises two drying chambers, two drums in the
?rst chamber, a continuous belt passing over the
drums, means for applying a solution of the rub
ber hydrochloride to the belt, a condenser, a
vapor outlet from the ?rst drying chamber con
necting said chamber with the condenser, means
for conveying the ?lm from the belt to the second
chamber .and for passing gas from the second
chamber to the ?rst chamber in contact with
said ?lm, means for introducing ?ltered air into 20
the second chamber and means in the second
chamber for supporting the ?lm to permit simul
taneous evaporation of liquid from both sides of
the ?lm therein.
2. Apparatus for the production of a trans 25
parent ?lm of a rubber hydrochloride which com
prises two drying chambers, two drums in the
?rst chamber, a continuous belt passing over the
drums, means for applying a solution of the rub
ber derivative to the belt, a condenser, a vapor 80
outlet from the ?rst drying chamber near said
means and connecting with the condenser, means
for conveying the ?lm from the belt to the second
chamber and for passing gas from the second
chamber to the ?gst chamber in contact with said
?lm, means for introducing ?ltered air into the
second chamber, air re-circulation means con
nected with each chamber and means for heating
the re-circulated air.
3. Apparatus_for the production of a trans
parent ?lm of a rubber hydrochloride which com
prises two drying chambers, two drums in the
?rst chamber, a continuous belt passing over the
drums, means for applying a solution of the rub
ber derivative to the belt, a condenser, a vapor 45
outlet from the ?rst drying chamber near said
means and connecting with the condenser, means
for conveying the ?lm from the belt to the second
chamber and for passing gas from the second
chamber to the ?rst chamber in contact with
said film and means in the'second chamber for
supporting the ?lm and exposing both surfaces
thereof to contact with the gas in said second
drying chamber.
4. Apparatus for the production of a thin ?lm
of a rubber hydrochloride which comprises two
drying chambers, in the ?rst chamber a continu
ous surface on which the ?lm is to be formed,
means for imparting uniform motion to said
surface, means for applying a solution of the
rubber hydrochloride to said surface, a condenser,
a vapor outlet from the ?rst chamber connecting
said chamber with the condenser, means‘ for con
veying the ?lm from said surface to the second
chamber and for passing gas from the second
chamber to the ?rst chamber in contact with said
?lm, and means in the second chamber for sup
porting the ?lm to permit simultaneous evap
oration of liquid from both sides of the ?lm
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