Note: Descriptions are shown in the official language in which they were submitted.
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The invention relate~ to a photographic film, which i~
pro~ided with a slidable layer in order to improve it~
frictional properties.
It is known that the sliding propertiss oi photographic
material~ may be impro~ed by using slipping agents or
lubricants. ~he sliding properties are of particular
importance with cinematographic and narrow-gauge film
material~, which are used in cassettes or magazines. There
i9 an optimal range as regard~ the ~liding properties of such
material~, since a slidability which i8 too high can be just
as disadvantageou~ as one which is too low. ~or example,
the position of the projected picture depends on a~hieving
the best posQible slidability. Ii the rear side of the fil~
material is too slidable, fluctuation~ in the picture position
may occur and these cannot be tolerated. On the other hand,
when the elidability is too low, tensile forces are set,up
whlch can impair the balance oi ioroes in the film cassette.
Known sliding agents or lubricants are, for example,
carnauba wax, bess wax, mineral waxes ~uch a~ ozokerite,
indu~trial waxes~ pararfin oil, eilicone oll, sodium
stearate, finely dispersed graphite, talcum, esters of
C14 - C20 monocarboxylic acids, triglycerides, stearoylamino-
benzene-sulphonic acid~ alkylmethyltaurides with C10-C20 alkyl
radicals, acylated taurines and B-dialkylaminopropionic acid.
None of the known lubricants influences the sliding
properties of a photographic material in the manner which
is necessary for film materials used for motion pictures.
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Usually, the lubricants increase the sliding properties of the ilm material,
so that the ~ilm does not i~mediately come to a stop when the feeding opera-
tions in the camera are halted. This supplementary sliding movement leads
to disruptions in the exposure of the film material.
An ob~ect of this invention is to improve the sliding properties
of photographic films, which are particularly but not exclusively intended
to be used in cassettes or magazines as a film material for motion pictures.
It has now been found that this object can be achieved with a
photographic film comprising a support layer, at least one light-sensitive
silver halide emulsion layer on one side of the support layer, and a slid-
; able layer uppermost on the other side, the slidable layer comprising an
ester of a polyhydric alcohol with a C10-C20 aliphatic carboxylic acid, and
the film having a frictional value of between 30 and 50 for the slidable
layer and polystyrene as a friction partner.
The esters of polyhydric alcohols with C10 to C20 aliphatic
carboxylic acids which are used according to the invention are advantageously
esters of palmitic acid or stearic acid. However, esters of other carboxylic
acids can also be used, for example, esters of aluric acid, myristic acid
or arachic acid. Examples of suitable polyhydric alcohols are ethylene
glycol, diethylene glycol, triethylene glycol, glycerine, pentaerythritol,
mannitol, sorbitol, glucose, fructose, saccharose (sucrose), dextrin, cellu-
lose or polyvinyl alcohol.
The consistency at room temperature of the esters used accord-
ing to the invention depends on chemical composition, and can be liquid,
syrupy, or like a soft wax or hard wax.
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Esters having a consistency similar to ~oft to hard wax and
having melting points above 50C are preferred.
The slidable layers used according to the invention
are applied to the back of the photographic material, remote
from the light-sensitive coating. The layer~ can either be
applied directly to the back of the film support or as an
outer layer or coating over other layers which have already
been applied, such as antistatic or antihalation layers.
~he last-mentioned of these possibilities is preferred.
~he effect of the layers or coatings when covered with
the slidable layers of the invention i9 not impaired in any
way.
~he slidable layers according to the invention may be
applied in the form of solutions to the back of the photo-
graphlc materials. Suitable solvents are particularly
¢hlorinated hydrocarbon~, such as, for example, trichlor-
ethylene, carbon tetrachloride, perchlorethylene, methylene
chloride, chloro~orm, 1,2-dichlorethylene or 1,1,1-trichlor-
ethane. ~hese solvents can either be used individually or
in admixture or in mixture~ with other organic solvents,
sUch as, for example, ethyl acetate, acetone, methyl ethyl
ketone or alcohols, for example ethanol. All solvents are,
in principle, suitable, provided they only have the necessary
dissolving properties for the esters used according to the
invention and have no deleterious effect on the function of
the layer which i~ therebeneath~ ~he thickne~s of the
~lidable layers and the amounts of the esters which are to
be applied are not in any way critical, since the sliding or
~lipping behaviour i~ established exclus~vsly by surface
phenomena. Nevertheles~, an applied quantity of le~s than
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1 mg/m should preferably not be used.
In another method of application, the compounds, com-
bined with water-insoluble polymer~, are diseolved and the
mixtures are applied to the back.
~he slidable layers can be applied to the back of the
photographic material by u~ing conventional coating methods,
such a~, for example, by spraying, brushing, rolling,
doctoring, air-brushing or spreading teehniques. Examples
of film supports to which the slidable layers of the
invention can be applled, either directly or after previous
coating with other backing layers, are films made of
¢ellulose triacetate, polyalkylene terephthalate, poly-
carbonates or polystyrene.
~he photographle material~ equipped in the manner
a¢eording to the invention show optimal sliding properties
when they are used in cas~ettes or magazines, more particu-
larly a~ narrow-gauge films in cassettes of the known super-8
~ystem.
~he irietlonal charaeterl~tics of the back of the film
and cas~ette material are oi de¢isive lmportance in the
functioning of a narrow-gauge film cassette. ~he friction
number ~, which is aleo de~ignated as the coefficient of
friction, quantitativel~ characterisee the frietional be-
~ haviour. The friction number is the ratio between the
i~ 25 frictio~al force which acts in the direction of movementof the film material, and the pressure-applying force which
acts perpendieular to the friction surface and with which the
two friction partners are pressed one against the other. For
praetlcal reasons, the friction behaviour is generally
characterised by the friction value ~p, which is the
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frictional force expressed as a percentage of the pressure-
applying force. This value i9 100 times the friction
number ~.
In the physics of frictional proce~es, a distinction
is made between starting friction and sliding friction.
While the starting friction (also known a~ adhesive friction
or static friction) characterises the force which is necess-
ary for the initiation of a sliding movement, the sliding
friction (also known as motional friction or dynamic
friction) characterises the force which i8 necessary to
maintain a specified constant sliding fipeed. For the same
frictional partners, the ~tarting friction is generally
higher than the sliding friction. The sliding friction is
particularly important as regards the aforementioned narrow-
gauge film ay~tem~. A frlctional value ~p of between 30
and 50 ie preferred for the ~riction partners comprising the
back Or the film and the cassette material, consisting of
polystyrene or styrene ¢opolymers. ~he fri¢tional values
indicated in the following examples are measured in ac¢ord-
an¢a with DIN 53 375 at a temperature of 23C and 50% relative
humidity. A¢¢ording to this method a film strip is drawn at
¢onstant speed under a metal block, on the underside of which
is disposed the respe¢tlve fri¢tional partner, which in the
pre~ent ¢ase is a ~mall ~heet o~ polystyrene or a styrene ¢o-
polymer. ~he back of the film to be tested i8 inserted
uppermost and fa¢es the underside o~ the loading blo¢k.
~his is coupled to a force-measuring arrangement.
The frictional values indicated in the following
examples ha~e been established ac¢ording to the above-
described method u~ing poly~tyrene as fri¢tlonal partner.
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For similar materials, such as, for example, styrene co-
polymers, the frictional values only deviate slightly and
in every case remain within the optimal range indicated
above.
The invention is more fully explained by the following
examples.
Example 1
To a film support, consisting of 100 parts by weight of
cellulose acetate, with an acetic acid content of 61.2 ~
by weight , and 15 parts by weight of triphenylphosphate,
the following antistatic solution is initially applied:
5 g of cellulose acetate maleate, sodium s~lt;
520 ml of water; and
480 ml of methanol.
After drying, the following solution is applied as a
slidable layer:
0.2 g of sucro~e distea~ate; and
1000 ml of trichlorethylene.
The amount of ester applied is 2 mg/m2 of film support and
the frictional value for sliding friction against polystyrene
is 42.
ExamPle 2 (comparison)
To a film support as described in Example 1, provided
with an antistatic layer or coating, a slidable layer having
the following composition is applied:
0.2 g of a normal commercial ester mixture of waxy
consistency, with a melting range of from 47
to 51C, an iodine number of about 7 and con-
sisting of an ester mixture of acids having from
10 to 20 carbon atoms and monohydric alcohols
having from 14 to 20 carbon atom3; and
1000 ml of trichlorethylene.
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In this case , the amount of ester applied is 2 mg/m2. The
:Erictional value for sliding friction against polystyrene was
established as 25. This result shows that an optimal sliding
behaviour cannot be achieved with the ester mixture.
i.xample 3 (comparison)
To a film support with an antistatic coating as described
in Example 1, a slidable layer consisting of the following
solution is applied:
0,2 g of an ester wax based on Montana wax (wax E
of Farbwerke Hoechst) with the following
characteristics: saponification number 150,
acid number 17, solidification point 72; and
1000 ml of trichlorethylene.
The applied quantity of ester is 2 mg/m2 and the frictional
value for sliding friction against polystyrene is 25. The
slidable properties are completely in~ufficient.
Exam~le 4
To a film support with an antistatic coating as
described in Example 1, the following slidable layer is
applied:
0.3 g of glycerine monostearate; and
1000 ml of trichlorethylene.
The applied quantity of ester is 3 mg/m2 and the sliding
frictional value against polystyrene is 35.
If glycerine monostearate in the slidable layer compo-
sition as indicated is replaced by glycerine monopalmitate, a
frictional value of 33 against polystyrene is obtained.
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ExamPle 5
To a film support as described in Example 1, an
antistatic coating having the following composition is
first of all applied:
3 g of polyurea of sodium 4,4'-diaminodiphenylethyne-2,2'~
disulphonate, corresponding to German Auslegeschrift
No. 1,081,754;
5 g of cellulose acetate with 56 % by weight acetic acid;
50 ml o~ water;
250 ml of methanol; and
700 ml of acetone.
To the dry coating the following solution is then applied
as a slidable layer:
0.5 g of diethylene glycol monostearate;
500 ml of trichlorethylene; and
500 ml of ethyl acetate.
The applied quantity of ester is 5 mg/m2 and the sliding
frictional value against polystyrene is 45.
ExamPle 6
A film support as described in Example 1 is provided
with the following antistatic coating:
5 g of polystyrene sulphonic acid, sodium sa~;
25 ml of water;
275 ml of methanol; and
700 ml of acetone.
A slidable layer of the following composition is then
applied:
0.~ g of sorbitol monostearate;
500 ml of trichlorethylene; and
-30 500 ml of acetone.
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The applied quantity of ester is 3 mg/m2 and the sliding
frictional value against polystyrene is 43.
Example 7
To a film support having an antistatic backing layer
as described in Example 1, the following slidable layer is
applied:
1.5 g of sucrose monostearate;
1.5 g of cellulose triacetate;
500 ml of methylene chloride; and
500 ml of trichlorethylene.
The applied quantity of solid substances is 35 mg/m2
and the frictional value of sliding friction against poly-
styrene is 45.
Example 8
To a biaxially stretched film support of polyethylene
terephthalate, the following solution is applied as an anti-
halation layer:
30 g of cellulose acetate phthalate;
10 g of carbon black;
100 ml of ethylene glycol monomethylether;
400 ml of methyl ethyl ketone; and
500 ml of ethanol.
After drying, the following slidable layer is applied:
2 g of ethylene glycol distearate;
500 ml of trichlorethylene; and
500 ml of methylene chloride.
The applied quantity of ester is 20 mg/m2 and the
sliding frictional value against polystyrene is 36.
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