US 2150757 A
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.tendency to the film to curl.
Patented Mar. 14, 1939 UNITED STATES PATENT OFFICE Agfa Ansco Corporation, Binghamton, corporation of New York N. Y., a
No Drawing. Application June 22, 1937, Serial No. 149,696
The present invention relates to a composition for effecting the rapid drying of photographic films.
It has been found advantageous to rapidly dry photographic negatives after the washing treatment designed to remove substances carried over from the fixing bath as such drying has the effect to lessen the duration of treatment. Rapid drying by the application of elevated temperatures is, of course, more or less hazardous because of the susceptibility of the emulsion to injuries and to the liquification of the gelatine layer at elevated temperatures. The practice has, therefore, been developed of using low boiling, water miscible solvents for removing the water carried by the film. Ethyl alcohol was originally used as such a solvent. Ethyl alcohol, however, has the disadvantage that it causes streaking or clouding of the film. Methy alcohol is less open to this objection and for this reason ethyl alcohol has to a great extent been supplanted by methyl alcohol. Methyl alcohol, on the other hand, has the drawback that it has a solvent action on the film base and thereby causes a softening and a permanent swelling of the base, which imparts a decided It is, therefore, manifest that methyl alcohol does not measure up to the practical requirements of the photographic art.
The object of the present invention is to provide a film drier which will cause a rapid drying of the film without a streaking of the film and without imparting any substantial softening or curling propensities to the film.
My rapid film drier is a composition essentially comprising a. dehydrating and a hardening agent to which the film and emulsion are inert, such as a low molecular weight aliphatic alcohol and a substance capable of hardening the gelatine layer. As the low molecular weight alcohol, which has the function of removing the water as by forming an azeotropic mixture therewith, I may use such alcohols as ethyl alcohol, isopropyl alcohol and the like either alone or in admixture with each other. Different hardening agents for gelatine such as formaldehyde, acetaldehyde, tannic acid, synthetic tanning agents, for example those comprising thiophenol such as that sold under the trade name Katanol and the like may be utilized, but for best results I recommend the utilization of formaldehyde. Generally the formaldehyde is employed in the form of a 40% solution in water.
While the principal and essential components of my drier are a dehydrating agent and a hardening agent, I find it advantageous to also include with said components a polyhydric alcohol or another softening agent such as glycerine, glycol, diethylene glycol and the like. The action of the polyhydric alcohol is not only to increase the flexibility of the hardened gelatine layer but it has been found that its presence in the film drier counteracts the tendency of the film to show blushing or to become cloudy, especially if the drying is carried on in an atmosphere of low relative humidity or at higher temperature.
Other components may also be incorporated in the composition. For instance it is often found desirable to cover the objectionable odor of formaldehyde and therefore to impart to the composition a pleasant odor by adding thereto a substance such as amyl acetate, essential oils and the like. Water may also be added to the composition, if desired. The quantity of water in no case, however, should exceed the quantity of dehydrating agent in the composition.
My invention is further illustrated by the following examples although it is to be understood that my invention is not restricted to these examples. Parts are by Parts Methyl alcohol 100 Formaldehyde 40% 10 Glycerine C. P 1,2
2 Methyl alcohol 67 Isopropyl alcohol 99% 33 Diethylene glycol 1.8 Formaldehyde 40% 10 Oil cinnamon .005 Oil nutmeg .005 Terpinol .02
Methyl alcohol 100 Water 9 Formaldehyde 40%-"--. 4.5 Glycerine C. P 1.2 Amyl acetate .6
4 Ethyl alcohol 100 Formaldehyde 40% 5 Ethylene glycol l0 Amyl acetate .5
The treatment baths of the present invention are used according to the conventional practice of the art, that is the film, after a thorough washing to remove salts carried over from the fixing bath, is placed in a receptacle containing the rapid drying solution. 'The ,fllmis permitted to remain in said solution for a period varying from 1 to 5 minutes. The film is then subjected to the action of theatmosphere whereupon the residual moisture and drying agents are evaporated. If desired, the evaporation of the moisture may be considerably accelerated by subjecting the film to the action of hot air.
Treatment baths according'to the present invention havebeenfound to very rapidly remove moisture carried by the film without the film suffering anyinjuries as theresult of being suby it can'be seen that said compositions possess par ticularadvantages especially when compared to jected to said treatment baths. Thus the film is not streaked as is the case when ethyl alcohol in a concentrated state is employed per se as a I drier.
tendency to curl. Inasmuch as the compositions of the present invention may be made up by the very simple expedient of mixing. the components thereof, and inasmuch as they produce the de- Nordo'es the film show brittleness or any sired result without injury to the film in any way,
the treating baths usedheretofore.
What I claim is:
l. A rapid film drier containing as its three essential components a volatile low -molecular' weight aliphatic alcohol, an aliphatic polyhydric alcohol and an agent capable of hardening or tanning gelatine, said first alcohol being the predominant component of the composition any waterimmiscible oil in the composition being present in very small amounts, said composition remaining homogeneous after extended use.
2. A rapid film drier containingas its three essential components ethyl alcohol, a polyhydric alcohol and aqucousformaldehyde, the ethyl alcohol being the predominant component of said composition any water-immiscible oilin the. composition being present in very small amounts, said composition remaining homogeneous after extended use.
3. A rapid film drier consisting of ethyl alcohol,
a polyhydric alcohol selected from the class con-,
sisting of 'a'glycerine and glycol, aqueous formaldehyde and a substance for imparting a pleasant odor to the composition, the ethyl alcohol being the predominant component or the. composition any water-immiscible oil in the composition being present in very small amounts, said i composition remaining homogeneous after exsaid composition remaining homogeneous after extended use. l l 5. A rapid film drier composition, consisting of 7 Parts Methyl alcohol 100 Water 9 Formaldehyde 40% 4.5 I Glycerine C. P y 1.2 Amyl acetate .6
said: composition remaining, homogeneous after 1 extended use. I
' 6'.-A rapid film drier compositiomconsisting of Parts Ethyl o ol I 100 Formaldehyde 40% 5 Ethylene glycol e 10 g y Amyl acetate .5
said composition remaining homogeneousafter extended use; I
HOWARD O. BODINE.