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Патент USA US2119727

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June 7, 1938.
Filed Aug. 7, 1956
. Ralph H. Talbot,
BY. W- W '
Sam! 9.
Patented June 7, 1938
_ _ 2,119,721
MANUFACTURE or aasm rrmus
aalpun. Talbot, ‘Rochester, N. Y., “in”, by
mesne assignments, to Eastman Kodak Com
pany, Jersey City, N. 1., a corporation of New
Application August ‘l, 1930, Serial No. 34,834
2 Claims.
(Cl. iii-s7)
This invention relates to the manufacture of
sheets or ?lms formed of various colloidal and
resinous materials and more particularly to a
method of facilitating the removal of ?lms com
posed of vinyl resins from the surface upon which
they‘ are cast.
ing or stretching or the production of “snap lines”
in the product.
In the following examples and description I
have set forth several of the preferred embodi
ments of my invention, ‘but they are'included
merely forpurposes of illustration and not as
As is'well known, various types of ?lm and a limitation thereof.
In the accompanying drawing, in which like
sheeting are made by depositing a dope or solu
tion of a colloidal material in athin layer on the‘ reference characters refer to like parts,
Fig. 1 is a schematic elevational view of a ma 10
10 surface of a slowly rotating wheel or drum, re
moving solvents by means of heated air or other _ chine adapted for the production of resinous
coagulating niedia. and finally stripping the co
agulate'd'material from the ?lm-forming surface
in a continuous sheet. At the point of stripping
15 the ?lm, particularly if it is resinous in nature,
retains a small amount of residual solvent, caus
ing it'to beslightly tacky and to adhere tena
ciously to the wheel surface. This adhesiveness
is particularly noticeable in films composed of
vinyl resins, and is probably due to the fact that
such ?lms retain very tenaciously small amounts
of residual solvent which cause the materialto
adhere strongly to the wheel surface. It has
?lms, particularly vinyl resin ?lms and illustrat
ing the manner in which the ?lm is removed from
the ?lm-forming surface in accordance with the.
present invention.
‘Fig. 2 is an enlarged fragmentary view more
fully illustrating the action of the liquid bead in
assisting in the removal of the ?lm from the
?lm-forming surface. -
Fig. 3 is a partial view similar to that of Fig. 1 20'
in which the stripping of another type of ?lm is
Fig. ‘i is another fragmentary view illustrating
been found that this adhesion tendency almost the use of a chill roll inconjunction with a liquid
25 invariably results in the production of so-called '
In carrying out my invention I apply a head of
"snap lines” on the. ?lm which render it defective
for photographic and other uses where practically non-solvent liquid to the crevice between the
perfect transparency is required. The adhesion stripped film and the surface upon which it is
, may-in some cases be so great as to cause-small
portions of the ?lm to be torn away from the
main body of the ?lm and left upon the ?lm
formed. Water, for .examplahas been found to
serve the purpose very well, although many other 30
non-solvent liquids may be employed. It has
been found that especially desirable results are
_ The present invention has as its principal object ' obtained if the liquid is applied in a cool or _
to obviatethe above-mentioned dimculties in the cold condition, the ?lm apparently being cooled
by the ?uid and stripping more readily in that 35
35 manufacture of resin sheets or ?lms and to pro
vide a means whereby such ?lms may be stripped condition. Further cooling by means of a chilled
roll applied as indicated in Fig. 4 is sometimes
from a ?lm-forming surface without the pro
duction therein of snap lines or similar optical desirable from the standpoint of further increas—
defects. Another object is to provide an. im
40 proved method of stripping vinyl resin ?lms from
the surface of a coating wheel such as is com
monly employed in the ?lm making industry.
Other objects will appear hereinafter.
. These objects are accomplished by the follow
4a ing invention which, in its broader aspects, com;
prises the application of a bead of liquid at the
point at which the ?lm is stripped from the ?lm
forming surface. ' I have found, for example, that
50 when employing a wheel for-casting the film, if
a liquid which is non-solvent with respect to the
?lm, such as cold water, is placed in the V-shaped
‘opening formed between ‘the wheel surface and‘
ing the ease of stripping.
As indicated, the material employed for pro-,, 40
ducing the head should be a liquid which has no
substantial solvent action upon the material of the - "
?lm and should, of course, be substantially non
corrosive with respect to the metallic‘ surface of
the coating wheel or other device upon which the 45
?lm is formed. ‘In the manufacture of vinyl resin
and other resinous types of ?lm, I ?nd that water
serves the purpose extremely well, since it has no
solvent action on the resinous material. Further- " “
more, water has the added advantages that it is 50
cheap and also that it exerts a slight solvent
extracting effect on the film. vOther liquids which
may be used in accordance with the invention are
‘the inner surface of the ?lm as it leaves the ' members of the aliphatic series of hydrocarbons
such as hexane, heptane, octane, etc. Under cer
55 wheel, the ?lm breaks away sharply without stick
tain circumstances aromaticv hydrocarbon _ such trolled'by valve II. The water or otheryliquid is
as toluene may be employed.
permitted to drop from the outlet it into the V
‘While I prefer to use cold water, that is, water _ shaped opening formed between the film-forming
cooled substantially below- room temperature. surface l8 and the inside surface of the film I3,
the matter of temperature does. not appear to thus maintaining a liquid bead I! at approxi
be critical. In some cases it vmay be desirable to mately the exact point of stripping. The supply
use water at temperatures above room tempera
of water may be continuous or intermittent, this
ture, while in other cases the temperature of
the ‘liquid may be close to the freezing point. In
10 either case, the effect obtained is substantially
the same, namely, perfect stripping of the film
without sticking, snap lines or other undesirable’
being immaterial so long as the bead is main
tained. It may be said that no great amount of
liquid need. be permitted to accumulate in the 10
- v, a relatively '?ne bead apparently being as effec
tive as a large bead.
' "'~.In Fig. 2 I have illustrated in enlarged section
vAt this point it. is desirable to point out ‘that the ’ the further action of the liquid bead in separat
16 action of the liquid bead is apparently not due to ing the ?lm from the film-forming surface. It 15
any difference in its temperature from that of will be-evi'dent that in some way,'the theoretical
the film material, but its action'is more akin to " explanation of which is not clear, the bead I! has
a mechanical action in that it causes the clean _ a very definite and positive action in splitting
cut separation of the film material from the
coating surface independently of any cooling
or chemical action.
While I offer no explana
tion to account for this phenomenon, it appears
that the results obtained are due to some type of .
physical actiontaking .place between the liquid
bead, the metal'illm-forming surface and the ?lm
My invention willbe more readily understood
by reference to the accompanying drawing. Re
ferring to Fig. 1, the numeral Ill designates a
the ?lm away from the film-forming surface.
This is remarkable and wholly unexpected when 20
one considers the fact that water is a mobile and
easily deformable liquid.
Figure 3 illustrates the, path which the film will
assume in the case of certain resins which tend
to cling more tenaciously to the coating surface 25
than others.
Some types of resin films will not
leave the wheel until they have reached a position
which coincides with a line normal to the coat
ing surface (radial to thewheel center) and ap
proximately tangent to the guide roll M. This 30
film making industry which receives from the reluctance» to leave the coating surface greatly
hopper H a viscous dope comprising a vinyl or. vaggravates the “snap back" tendency above-de
other resin dissolved in appropriate solvents. _ scribed, but this is, however, entirely overcome in
This dope is caused to flow upon the polished accordance with the instant invention by the
35 wheel surface at such a‘depth and speed as will introduction of the water bead It.
The smoothness of the stripping action may
produce a finished film it of the desired thickness,
the depth of the dope at the hopper being con
be further improved by the addition of a chill roll
trolled by means of a gate i2 in- known manner. 20 (Fig. 4) which is preferably hollow and sup
The wheel slowly rotates in the direction indicated plied with low temperature brine 2! or other suit
by the arrow, while a current of heated air, or able cooling medium. This tends further to 40
other coagulating medium is circulated around harden or “set’?the film before 'actual stripping
the wheel surface preferably in a direction
In carrying out the invention herein described
counter-current to they direction of rotation,
whereby solvents are removed from the ?lm. _by applying a bead of liquid-at the point of strip
The customary air-circulating housing is not ping it is desirable that none of the liquid shall .45
shown in the drawing, being of a conventional be carried up on the wheel surface from the strip
ping point' and thus come in contact'with the
design well known in the art.
30 coating wheel of a conventional type used in the
The film It is detached or stripped from the .hopper as this would cause streaks in the film
film-forming surface when the wheel III has being formed. _ In order to‘ prevent this carrying
over of liquid from the bead, I prefer to .dry the 50
passed through about three-quarters of a revolu
tion, being guided over roll it and thence to an wheel surface by application thereto of a cloth
appropriate drying apparatus (not shown). At pad saturated with acetone or alcohol positioned
this point, the film may contain varying amounts a short distance from the point of stripping in
such manner as to bear lightly on the wheel sur
of residual solvent occluded therein and has vary
55 ing degrees of tackiness or tendency to adhere . face. The acetone or alcohol .absorbs any water 55
to the film-forming surface, depending upon the or other liquid which may be carried up and
particular type of resinous material of which the makes certainthat the surface with which the
film is formed and also upon the amount of re
_ film-forming solution comes in contact is always .
sidual solvent. My- invention has, for example, in proper condition. Various other expedients
been found particularly effective in stripping' for drying the wheel surface and preventing the 60
films produced ‘from. such resinous materials as carrying over of the bead liquid may be employed,
that sold under the trade name "Formvar” which
is a vinyl acetal resin derived from the condensa
tion of partially hydrolized polyvinyl acetate with
65 formaldehyde, the preparation of which is re
ferrred to in British Patent 351,082, and many
others; and that sold under the trade name
"Alvar” which is an acetal derived from the con
densation of partially hydrolyzed polyvinyl ace
70 tate with acetaldehyde, the preparation of which
is described in British Patent 351,082.
In accordance with the invention, a suitable
supply of water or other non-solvent liquid is
supplied from a suitable source through pipe i5,
75 terminating in an outlet I61, the flow being con
as will be apparent to those skilled in the art of
film manufacture.
As will be apparent, many changes may be
made in the above described method of carrying 65
out the process within the scope of my‘ invention.
It will also be understood that the invention is
applicable to the manufacture of ?lms produced
from a wide variety of resins, including vinyl
resins, such as polymerized polyvinyl esters, vinyl 70
halides, and acetal condensation products of
hydrolyzed vinyl esters, such as hydrolyzed poly
vinyl acetate or polyvinyl alcohol with various
aldehydes, such as formaldehyde, acetaldehyde,
butyraldehyde, furfural and others, or mixtures
thereof, as well as many other types of resinous
It will also be evident that my invention is not
material in the form of a ?lm on a ?lm-forming
limited to the production of ?lms on wheel sur
ping the ?lm from the surface in a direction
which comprises casting a solution of a colloidal
surface, removing solvent therefrom and strip
faces, but may also be applied to the manufac
which provides an approximately V-shaped 5
ture of ?lms on metallic endless bands, since it is
obvious that a bead of liquid may be main
crevice between the ?lm and the surface in
which the vertex of the V is at least as low as
tained at the point of stripping in such devices
any other point of the V, maintaining a supply
of a non-solvent liquid in the crevice by gravity
and simultaneously applying a cold roll approxi
mately at the point of stripping but von the side
of the ?lm opposite the non-solvent.
2. The process of producing a sheet or ?lm
which comprises casting a solution of a colloidal.
as well as in the wheel type of casting appara
While I have found it convenient to describe
my invention by the use of water as an example
it is apparent that any ?uid which does ‘not
have a solvent or chemical action upon the ?lm
16 or a corrosive action on the machinery may be
material in the form of a ?lm on a'continuously 15
moving ?lm-forming surface, removing solvent The herem described invention constitutes _a therefrom and stripping the ?lm from the con
simple, economical ‘and highly effective solu
tinuously moving surface in a direction which '
tion of the problem of stripping ?lms from their provides an approximately .V-shaped crevice be
20 forming surfaces. without damage to, or de ‘ tween the ?lm and the surface in which the ver
struction of, the ?lm or ?lm-forming surfaces. tex of the V is at least as low as any other
The process is especially valuable when making point of the V, maintaining a supply of a non
?lms from vinyl type resins which have a pro
solvent \liquid in the crevice by gravity and si
multaneously applying a cold roll approximately
nounced tendency to stick or adhere to the sur
faces upon which they are formed.
at the point of stripping but on the side of the
- What I claim is:
1. The process of producing a sheet or ?lm
?lm opposite the non-solvent.
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