US2096616A - Manufacture of photographic film - Google Patents

Description

Oct. 19, 1937. I I G. F. NADEAU- ,096, 6 I I MANUFACTURE OF PHOTQGRAPHIC FILM I Original Filed June 22, 1935 2 Shets-Sheet 1 D- x I 0 SENSITIVE EMULSION ELATIN SUB CELLULOSE NIT RATE 0!? ACETATE UNDERCOAT FDLYBASIC ACID'POLYHYDRIC ALCOHOL RESIN UNDERCOAT SUCH-A8 GLYPTAL OR ALKYD RESIN CELLULOSE DERIVATIVE SUPPORT SENSITIVE EMULSION MIXED GELATIN'RESIN SUB J CELLULOSE DERIVATNE SUPPORT jrwenkw:

Oct. 19, 1937.-

G. F. NADEAU' MANUFACTURE OF PHOTOGRAPHIC FILM Original Filed June' 22, 1935 v 2 Sheets-Sheet '2 Patented Oct. 19, 1937 UNITED STATES PATENT OFFICE MANUFACTURE OF PHOTOGRAPHIC FILM Gale F. Nadeau, Rochester, N. Y., assignor, by mesne assignments, to Eastman Kodak Com-.- pany, Jersey City, N. J., a corporation of New Jersey Application June 22, 1935, Serial No. 27,915 Renewed March .30, 1937 18 Claims.

Thisinv'ention relates-to photographic mateport, two ratherserious problems are encountered.

One is to get the emulsion to stick properly to the support, and the other is to attain the requisite degree of flexibility. When the adhesion is good,

the film as a whole is often brittle and will fracture even with moderate bending. This is probably due to the fact that, since the emulsion adheresso closely to the support, it is, broadly speaking, substantially continuous with it. Accordingly, as soon as the emulsion breaks,'the energy of impact produced by the fracture is transmitted directly to the support and causes it to break also. Experience has shown thatwhen the emulsion adheres less tenaciously to the support, the film is often found to have-unsatisfactory stripping qualities, that is, the emulsion can be lifted or stripped from the base or. support too readily to meet the requirements of many photographic uses. It has accordingly always been found necessary heretofore to effect some sort of compromise between adherence on the one hand and brittleness on the other, and it is well known that one property invariably gained at the expense of the other.-

As is well known, gelatin emulsions (which are colloidal solutions or dispersions of gelatin in water) cannot be made to adhere directly to a cellulose derivative support, because water will not wot this type of surface. It is accordingly necessary to apply to the cellulose derivative support a thin layer, substratum, or su as it is generally called, of gelatin in order to provide a. surface to which the emulsion will stick. Al-' though a gelatin emulsion, as such, will not adhere to the support, agelatin sub can be made'to adhere if it is applied from a subbing solution containing. solvents which, not-only wet, but superficially attack, soften, or swell the cellulose derivative material and thus assist in anchoring the gelatin thereto. Once the gel sub is applied, it is a relatively simple matter to make the lightsensitive aqueous emulsion stick to the support, since water will readily wet and soften the surface of the gel coating and the emulsion can thus be made to adhere to it.

It should be pointed out that when an emulsion is applied to a gel-subbed base, the emulsion and gel sub tend to merge and form what, for all intents and purposes, may be considered a single continuous gelatin layer on the film, and that the degree of adherence of the emulsion to the support is dependent upon the degree of adherence of the gel sub to the support or to the intervening substrata, if any. This adherence of the gel sub is controlled in practice by controlling the strength of the gel subbing solution, that is, the solvent or softening power of the subbing solution on the cellulose derivative material or intervening substrata. This control of solvent or softening power of the solution is accomplished by regulating the kind or amount of each of the solvents used in compounding it. A strong gel subbing solution is, according1y,'one which has a relatively strong solvent, softening or swelling action on the support material and causes the deposited gel sub to adhere tenaciously thereto, while a "weak subbing solution is one which is only weakly solvent with respect to the support material and will cause the deposited gelatin coating to adhere only slightly. In general, it may be said that the stronger the gel subbing solution, the greater will be the degree of adherence of the sub to the support and the greater the brittleness of the completed film.

The problem of obtaining proper adherence of the emulsion without an undue increase in brittleness is a dimcult one, especially when dealing with the so-called safety types of films in which the support is formed from a cellulose organic derivative, such as cellulose acetate. When employing cellulose nitrate as the support, it is pos sible to use a relatively weak gel subbing solution and thus, to a certain extent, to keep the [adherence (and consequently brittleness) down to approximately the proper value, but with cellulose organic derivative supports, such as those formed of'cellulose acetate, or cellulose acetate propio- .nate, for example, much stronger subbing solutions must be employed with the result that excessive adherence, and therefore excessive brittleness occurs. It has accordingly been necessary with this latter type of support, first'to apply a thin cellulose nitrate undercoat (which can itself be subbed with relatively weak subbing solutions), and then to apply a gel sub to the'nitrate surface, followed by the emulsion coating, but this is disadvantageous because of the fact. that it introduces a certain amount of cellulose nitrate into the finished film, making it difficult to meet the underwriters specifications for safety film. Aside from this attempted solution of the problem, the question of brittleness (where emulsion adherence was satisfactory) has remained substantially the same and even films including nitrate undercoats have proved insufliciently free from this defect to meet all of the rigid requirements of cinematographic use. I

In an attempt to solve this problem of obtain-. ing proper flexibility without an undue sacrifice of emulsion adherence, it has been proposed to employ an extra heavy cellulose nitrate undercoat underneath the gel sub and, while this expedient does appreciably increase flexibility, without an extra large decrease-in adherence, it sufiers the disadvantage pointed out above, namely, that it introduces a relatively large amount of cellulose nitrate into the finished product. Many other expedients looking toward the same end have been employed, for example, the use of an undercoat of rubber or similar material, but it has been found that, similarly to cellulose derivative undercoats, the impact arising from rupture of the emulsion is transmitted through the rubber layer, causing it to break, and that this break is carried on into the material of the underlying support. Somewhat similar to such products, and suifering many of the same defects, are various laminated structures in which bases consisting of cellulose organic derivatives or other materials have applied thereover a layer or layers of resinous or rubber-like materials of substantial thickness, these layers constituting a material part of the support and being applied, either in the form of separate sheets united to the base by appropriate cement, or deposited, as coatings, from appropriate solutions.

It is the principal object of the present invention to overcome the above-mentioned prior art difficulties and to provide a photographic film having a high degree of flexibility or freedom from brittleness and at the same time satisfactory emulsion adherence. A further object is to provide an improved type of safety film in which flexibility is rendered completely independent of the degree of adherence between the emulsion and the underlying substrata. A specific object is to .provide a film having a, polybasic acid-polyhydric alcohol resin sub or undercoat between thelight-sensitive gelatin layer and the film base. Other objects will appear hereinafter.

I have found that if the support is first coated with a thin layer consisting essentially of a poly-' basic acid-polyhydric alcohol resin almost any strength of gel subbing solution may be employed in the subbing operation and the gelatin emulsion may be subsequently bound to the gel sub and other substrata as tightly as desired without giving rise to brittleness in the finished film. .In other words, the use as undercoats of resins of the type indicated renders the matter of flexibility independent of the degree of adherence existing between the emulsion and the underlying substrata.

In the accompanying drawings I have illustrated in greatly exaggerated section several film structures produced in accordance with my invention and a test by which the flexibility of such films may be determined.

Figs. 1 and 2 are sections through the body of a completed photographic film produced in accordance with my invention and including a glyptal resin sub.

Fig. 3 illustrates another type of film employing a glyptal resin as a component of a sub layer.

Figs. 4 and 5 illustrate the manner of carrying out a brittleness test as described herein.

Figs. 6 and 7 illustrate the behavior of a relatively brittle film when subjected to the test illustrated in Figs. 4 and 5.

Figs. 8, 9, and 10 illustrate the behavior of a film such as shown in Figs. 1, 2, and 3 upon being subjected to the brittleness test.

In the following examples and description, I have set forth several of the preferred embodiments of my invention, but they are included merely for purposes of illustration and not as a limitation thereof.

After carrying out extensive work with various types of resinous materials, I have found that in order to fulfill the requirements of use as a substratum or undercoat in photographic film, the resin must be sufficiently adhesive when applied in appropriate solvents to stick properly to the cellulose derivative material of the support, that is, so that the completed film will pass the stripping tests herein described. The resin must also be compatible with the cellulose derivative and with the photographic emulsion in the sense that it shall not fog or reduce the sensitivity thereof or adversely affect any of the various processing steps to which the film is subjected during development. All of these requirements I have found are fulfilled by the glyptal resins (sometimes sold under the trade name Rezyls). These resins are the products formed by reacting a polyhydr'ic alcohol, such as glycerine, with phthalic acid or its anhydride. A typical method of preparation is described on page 293 of the 1923 edition of the text by Carlton Ellis entitled Synthetic resins and plastics," published by the Chemical Catalog Company. Also included in this category are the alkyd resins, a modified type of glyptal which may be prepared by reacting a polybasic organic acid, with an alcohol having three or more hydroxyl groups in the molecule, a dihydric alcohol, and a dibasic aliphatic acid. The nature of these resins is more fully described in an article beginning on page 971 of vol. 25 of the Journal of Industrial and Engineering Chemistry (1933).

The subbing of the film support with the resin solution may be carried out by any technique well known to those skilled in the art. The material may be conveniently applied to a cellulose acetate support, for example, from a 2% to 10% solution in methyl or ethyl alcohol and acetone, methyl cellosolve, or any other suitable solvent for the resin. After drying, the resin-coated support is preferably coated with a thin protective layer of cellulose nitrate, cellulose acetate, or other cellulose derivative, merely as a matter of convenience in handling the material in subsequent operations, although these protective layers are not absolutely necessary in all cases, since it is a fea ture of the glyptal and alkyd resins that they are not, in general, sufficiently tacky to require them. A thin gelatin sub is .then applied to the protective coating in order to form a proper surface upon which to deposit the final coating of emulsion, as previously described. The application of the resin, cellulose derivative and gelatin layers may be accomplished by any of the well known subbing operations, such as immersion, bead application, or otherwise. The material may be coated with the resin on one or both sides, de-

pending upon the type of film being produced. For example, in portrait film a coating of gelatin is deposited on the surface opposite the emulsion to give greater fiatness to the product, while in X-ray film the emulsion is deposited on both sides of the support. In both of these cases, the

support may be coated with the resin in accord-' ance with my invention.

Example 1 In producing a film "in accordance with one form of my invention, a support consisting. of a sheet or-film of cellulose acetate is led through an immersion type hopper containing an 8% solution of a glyptal resin in acetone at a linear speed of approximately 3 feet per minute. port is then led through an. appropriate drying apparatus maintained at a temperature of approximately 120-200 FL, where the solvent is evaporated from the surface of the material and a resin layer of approximately .00008 inch in thickness is deposited. The resin-coated material is then carried through asecond immersiontypehopper containing a solution of cellulose derivative material, say, a 2 solution of a high alcoholsoluble, low viscosity nitrocellulose dissolved in a solvent comprising 90% of methyl alcohol and 10% of butyl alcohol or a suitable cellulose acetate solution. Following appropriate drying of the nitrate coating, which is also extremely thin (of approximately the same order of thickness as the resin coating) the material is given a third extremely thin coating or sub of gelatin by the immersion or equivalent method, the gelatin solution or dispersion in this case consisting essentially of gelatin dissolved in a solvent mixture comprising I Per cent by weight Gelatin 1.0 Acetic acid 0.5 Water 10.0 Methanol 88.5

The gelatin-coated material is then dried at an appropriate temperature. and the usual gelatinosilver halide emulsion coating deposited on the gelatin surface in a well known manner, thus completing the film.

Example 2 Per cent by weight Gelatin 1.0 Acetic acid 1.0 Water 4.0 Acetone v 58.0 Methyl alcohol 36.0

After drying the gelatin layer, the light-sensitive emulsion layer is deposited on the film as before. The solvents employed for making up the subbing solutions will of course be selected upon the basis of the particular resin dealt with and the material of the support to which the solutions be dissolved in acetone or amixture of 80-90% The sup acetone and 20-10% methyl alcohol. Other solvents, such as methyl cellosolve and ethylene dichloride may be used in place of acetone if desired.

As will be observed from the above examples, various protective layers may be employed over the resin coating, if desired, although, due to the comparatively non-tacky character of the glyptals and alkyd resins, these layers may not be required. These layers may be composed of cellulose nitrate, cellulose acetate, and, in fact, almostv any of the cellulose ester compositions customarily used for film making purposes. Likewise, the material of the support may be composed of any suitable cellulose organic derivative material, such as cellulose acetate, cellulose propionate, cellulose butyrate, or a mixed cellulose organic ester, such as cellulose acetate proplonate, cellulose acetate butyrate, cellulose acetate stearate, and the like. Although not limited thereto, my invention relates primarily to the manufacture of the so-called safety types of photographic filin in which the support is composed of a relatively non-inflammable material, such as the cellulose organic esters, since-it is with this type of material that the problem of brittleness is most severe.

Although in the above examples,'I have found it convenient to illustrate my invention by reference to photographic films coated or subbed on one side only, the use of glyptal and alkyd resins as subs as herein described, may be applied with equal success to products, such as portrait film, in which a coating of gelatin is deposited on the surface opposite the emulsion coating to give greater flatness to the film or X-ray film which is gel and'emulsion-coated on both surfaces. It will be apparent that in such products, it is as necessary to prevent brittleness arising from the application of the gelatin or other subs on one side of the film as on the other. I have found that brittleness is as effectively prevented by the use of the thin resinous layers in accordance with by invention as in the case of those films which.

have gelatin layers or coatings on one surface only.

The improvement made possible by my invention will now be made clear by a discussion of the results obtained in carrying out certain tests on the finished emulsion-coated film. These are the so-called dry stripping, wet stripping, and brittleness or flexibility tests.

The dry stripping test is carried out as follows: A piece of the complete emulsion-coated film of a convenient size, say. 6 inches wide'by 40 inches long, is held at one end with both hands with the emulsion side toward the operator and is then torn lengthwise with successivequick motions of one hand, the tearing generally being carried out at a slight angle to the edge of the strip in order to obtain an oblique tear. The tars thus produced are more or less jagged. An attempt is now made to pull back the emulsion coating from the film with the fingernails and the degree to which the emulsion separates from the support is a measure of its adherence. It will, of course, be understood that the standards of emulsion adherence will vary for different types of film and what is considered satisfactory for one film may not be satisfactory for another. For example, stripping (emulsion adherence) is said to be satisfactory for X-ray film if the emulsion cannot be stripped back more than three or four inches. For Cine film, on the other hand, the stripping should not be greater than about $4 of an inch.

The wet stripping test is carried out as follows: A strip of the emulsion-coated film of convenient size is soaked in water at 70 F. for ten minutes. It is then removed from the water and fixed on a fiat surface with the emulsion side up. The emulsion is then gouged or creased with the fingernails at points near the middle and end of the strip, each nail scratch tearing the emulsion away from the support to a certain extent. The

scratched places are then rubbed with considerable force with the balls of the fingertips for several seconds. A film is said have satisfactory wet stripping (emulsion adherence) properties when no peeling, or substantially no peeling, of the emulsion occurs as a result of this rubbing action. Wet stripping is said to be unsatisfactory when an appreciable or large amount of the emulsion comes off. For most types of film it should not be possible to remove pieces wider than A, inch by this test.

The brittleness test is carried out as follows: A strip of film of convenient size is heated for forty-five minutes in a brittleness oven in which air having a controlled relative humidity of 20-25% and a temperature of 110-120 F. is circulated. The film is then removed from the oven and folded at ten difierent places along the strip by pressing the fold suddenly between the forefinger and the thumb. If the film is brittle, this sudden folding will cause it to break or snap in two at the fold. The flexibility may be defined in terms of freedom from brittleness which may be figured directly in percentages from the results of the test. For example, a film is said to be 60% free from brittleness if it ruptures at only four out of ten folds.

My inventionwill be further understood by reference to the accompanying drawings. In Fig. 1 I have illustrated a section through a photographic film produced substantially as described in Example 1 in which the letter A designates a cellulose derivative support composed of cellulose acetate, for example. Superimposed on and tightly adhering thereto is an extremely thin undercoat X composed of a glyptal or alkyd resin, this undercoat being approximately .00008 inch in thickness. B designates a thin protective layer of cellulose nitrate or cellulose acetate, while 0 is a thin gelatin sub which adheres to the cellulose nitrate or acetate layer B. D is the final gelatino-silver halide emulsion layer which adheres tightly to the gelatin sub C.

Fig. 2 represents a film structure prepared as described in Example 2 and differing from that of Fig. ,1 in that the protective cellulose derivative layer B has been omitted, it being one of the features of these resins that they may be conveniently handled without a protective coating due to the fact that they are not tacky at ordinary temperatures or the temperatures customarily met with in film manufacture.

In Fig) 3 there is illustrated a film structure involving the use of a glyptal resin in a sub layer X, but in this case the sub layer is a mixture of the resin with gelatin or other colloidal material. This particular form of my invention embodies also an invention of G. S. Babcock covered by his copending application Serial No. 27,409, filed June 13, 1935, assigned to the assignee of the in stant application.

Figs. 4 and 5 illustrate graphically the manner of carrying out the brittleness test above referred to. The film F, after removal from the brittleness oven, is folded at a given place into the form of a. short loop, the gelatin layer D being outermost. This loop is then closed by means of the forefinger and thumb, the pressure being applied as suddenly as possible and in the direction indicated by the arrows in Fig. 5.

In Figs. 6 and 7 there are illustrated the results obtained when an ordinary type of photographic film comprising,-a support A, a thin cellulose derivative undercoat B over the support, a gel sub C over the cellulose derivative undercoat, and the emulsion layer D over the gel sub,is subjected to the test. It will be seen that the crack starting in the emulsionpenetrates through layers B and C and goes on into the material of the support. This crack almost invariably continues on through the support with the result shown in Fig. 7. The film here illustrated is a typical prior art product and one from which the resinous sub or undercoat of the present invention is absent. This product is also one in which there is a high degree of adherence between the emulsion and the gel sub layer and between these layers and the underlying cellulose derivative material.

Fig. 8 illustrates the results obtained when a film employing the resinous subs or undercoats of my invention is subjected to thetest illustrated in Figs. 4 and 5. The film of Fig. 8 is in all respects the same as that illustrated in Figs. 6 and 7 except that a layer X of a glyptal resin has been applied to the support before application of the cellulose derivative layer, the gel sub C, and the emulsion coating D. The emulsion is made to adhere to the support with the same degree of tenacity as in the product illustrated in Figs. 6 and 7, but the product of Fig. 8 differs from that of Fig. 6 in the fact that, although the crack starting in the emulsion may continue through the gel sub, the cellulose derivative sub and even the resin layer itself, it does not in any case, penetrate into the support itself.

Figs. 9 and 10 illustrate the results obtained when these film structures are submitted to the test outlined in Figs. 4 and 5. In the structure of Fig. 2 the crack starting in the emulsion layer penetrates the gelatin and resin layers C and X, but does not penetrate the support itself. A similar result is obtained with the product of Fig. 3 as illustrated in Fig. 10.

This test strikingly illustrates the fact that a photographic film produced in accordance with my invention is characterized by the unusual property of 100% freedom from brittleness or, in other words, it has 100% flexibility. In addition to this remarkable property, such films respond satisfactorily to both the wet and dry stripping tests above described. In this connection it should be pointed out that one of the outstanding features of my invention is the fact that the adherence of the emulsion may be regulated without regard to the flexibility of the film. In other words, it is possible to produce a film in which the emulsion adheres to the support with the highest practicable degree of tenacity without inducing any brittleness whatever in the film as a whole or causing the support material to break on bending, either during cinematographic or other use, or when subjected to the tests herein described.

While I offer no particular explanation or theory to account for the unusual results obtained in the practice of my invention, it is evident that the resinous subs or undercoats herein described oifer some means of dissipating the impact of the rupturing emulsion on the film base. This effect is to be distinguished from the mere cushioning effect characteristic of elastic or semithese layers may even be released from the support to a slight extent but in no case does the break penetrate the material of the support itself.

Iri the above description and in the claims I have used the terms substratum, sub layer ibility and free from brittleness, comprising a. cellulose organic derivative support and a photographically sensitive colloid layer adhesively or sub, subbing, undercoat, etc. By a substratum, sub layer or sub I refer broadly to any layer, whether composed of a single layer or a plurality of layers, employed between the emulsion and the film base. The term undercoat refers to a single layer used underneath any other layer except the emulsion. It is customary;

however, in the case of a plurality of layers underneath the emulsion to refer to the layer next to the emulsion as a sub and the underlying layers as undercoats. The term subbing is employed broadly to; indicate the application of a thin layer of a material to the surface of a film, whether previously coated or not,

Furthermore, by the term sub" I refer to ex tremely thin layers or undercoats of material of the order of only a few millionths of an inch in thickness, such, for example, as the resin layer of Example 1. Inasmuch as the thickness of these layers is of this extremely small order of magnitude, it is evident that it may vary by a number of millionths, either above or below the preferred thickness of .00008 inch.- It will also be evident that the thickness of these subs will vary in accordance with the usual variations met with in the type of film base used. The thicker types of film base tolerate a slightly thicker sub, although in no case is the thickness sufiicient to be regarded as a lamination in the ordinary sense of the word as in those cases where a laminated film base is built up by the superimpositionof a number of layers of appreciable or relatively substantial thickness.

What I claim is: I

1. A photographic film of satisfactory flexjoined to the support by a composite intervening layer comprising an extremely thin sub composed of .a polybasic acid-polyhydric alcohol resin adhesively joined to the support, a cellulose derivative sub adhesively joined tothe resin sub and a gel sub adhesively joined to the cellulose derivative sub and to the sensitive colloid layer, said intervening layer rendering the flexibility characteristics of the film as a. whole in- .layer comprising an extremely thin sub composed of a glyptal resin adhesively joined to the support, a cellulosederivative sub adhesively joined to the resin sub and a gel sub adhesively joined to the cellulose derivative sub and to the sensi-. tive colloid layer, said intervening layer rendering the flexibility characteristics of the film as a. whole independent of the degree of adhesion existing between the photographically sensitive Y layer and the subbed support.

3. A photographic film of satisfactory flexibility and free from brittleness, comprising a eel lulose organic derivative support'and a photographically sensitive colloid layer adhesively joined to the support by a composite interven-' ing layer comprising an extremely thin sub composed of-an alkyd resin adhesively joined to the support, a cellulose derivative sub adhesively joined to the resin sub and a gel, sub adhesively joined to the cellulose derivative sub and to the sensitive colloid layer, said intervening layer rendering the flexibility characteristics of the film as a whole independent of the degree of adhesion existing between the photographically sensitive layer and the subbed support.

4. A photographic film of satisfactory flexibility and free from brittleness, comprising a cellulose organic derivative support and a photographically sensitive colloid layer adhesively joined to the support by a composite intervening layer comprising an extremely thin sub composed of .the resinous reaction product of a mixture of er rendering the flexibility characteristics of the film. as a whole independent of the degree of adhesion existing between the photographicall sensitive layer and the subbed support.

5. A photographic film of satisfactory flexibility and free from brittleness, comprising a cellulose organic acid ester support and a photographically sensitive colloid layer adhesively joined .to the support by a composite intervening layer comprising an extremely thin sub composed of a polybasic acid-polyhydric alcohol resin adhesively joined to the support, a cellulose derivative sub adhesively joined to the resinsub and a gel sub adhesively joined to-the cellulose derivative sub and to the sensitive colloid layer,

said intervening layer rendering 'the flexibility characteristics of the film as a whole independent of the degree of adhesion existing between the photographically sensitive support.

layer and the subbed 6. A photographic film of satisfactory flexibility and free from brittleness, comprising a cel'- lulose organic acid ester support and a photographically sensitive colloid layer adhesively joined to the support by a. composite inter-vening layer comprising an extremely thin sub composed of a glyptal resin adhesively joined to the support, a. cellulose derivative sub adhesively joined to the resin sub and a gel sub adhesively joined to the cellulose derivative sub and to the sensitive colloid layer, said intervening layer rendering the flexibility characteristics of the film as a whole independent of the degree of adhesion existing between the photographically sensitive layer and 'the subbed support.

7; A photographic film of satisfactory flexibility andfree from brittleness, comprising a cellulose organic acid ester support and a photographically sensitive colloid layer adhesively joined to the support by a-composite intervening layer comprising an extremely thin sub com-.

posed of an alkyd resin adhesively 'joined to the support, acellulose derivative sub adhesively joined to the resin sub and a gel sub adhesively joined to. the cellulose derivative sub and to the sensitive colloid layer, said intervening layer rendering the flexibility characteristics of the film as a whole independent of the degree of adhesion existing between the photographically sensitive layer and the subbed support.

8. A photographic film of satisfactory flexibility and free from brittleness, comprising a cellulose organic acid ester support and a photographically sensitive colloid layer adhesively joined to the support by a composite intervening layer comprising an extremely thin sub composed of the resinous reaction product of a mixture of a polybasic acid, an alcohol having three or more hydroxyl groups in the molecule, a dihydric alcohol and a dibasic acid adhesively joined to the support, a cellulose derivative sub adhesively joined to the resin sub and a gel sub adhesively joined to the cellulose derivative sub and to the sensitive colloid layer, said intervening layer rendering the flexibility characteristics of the film as a whole independent of the degree of adhesion existing between the photographically sensitive layer and the subbed support.

9. A photographic film of satisfactory flexibility and free from brittleness, comprising a cellulose acetate support and a photographically sensitive colloid layer adhesively joined to the support by a composite intervening layer comprising an extremely thin sub composed of a polybasic acidpolyhydric alcohol resin adhesively joined to the support, a cellulose nitrate sub adhesively joined to the resin sub and a gel sub adhesively joined to the cellulose derivative sub and to the sensitive colloid layer,- said intervening layer rendering the flexibility characteristics of the film as a whole independent of the degree of adhesion existing between the photographically sensitive layer and the subbed support.

10. A photographic film of satisfactory flexibilty and free from brittleness, comprising a cellulose acetate support and a photographically sensitive colloid layer adhesively joined to the support by a composite intervening layer comprising an extremely thin sub composed of a glyptal resin adhesively joined to the support, a cellulose nitrate sub adhesively joined to the resin sub and a gel sub adhesively joined to the cellulose nitrate sub and to the sensitive colloid layer, said intervening layer rendering the flexibility characteristics of the film as a whole independent of the degree of adhesion existing between the photographically sensitive layer and the subbed support.

11. A photographic film of satisfactory flexibility and free from brittleness, comprising a cellulose acetate support and a photographically sensitive colloid layer adhesively joined to the support by a composite intervening layer comprising an extremely thin sub composed of an alkyd resin adhesively joined to the support, a cellulose nitrate sub adhesively joined to the resin sub and a gel sub adhesively joined to the cellulose nitrate sub and to the sensitive colloid layer, said intervening layer rendering the flexibility characteristics of the film as a whole independent of the degree. of adhesion exitsing between the photographically sensitive layer and the subbed supp I 12. A photographic film of satisfactory flexibility and free from brittleness, comprising a cellulose acetate support and a photographically sensitive colloid layer adhesively joined to the support by a composite intervening layer comprising an extremely thin sub composed of the resinous reaction product of a mixture of a polybasic acid, an alcohol having three or more hydroxyl groups in the molecule, a dihydric alcohol and a dibasic acid adhesively joined to the support, a cellulose nitrate sub adhesively joined to the resin sub and a gel sub adhesively joined to the cellulose nitrate sub and to the sensitive colloid' layer, said intervening layer rendering the flexibility characteristics of the film as a whole independent of the degree of adhesion existing between the photographically sensitive layer and the subbed support.

13. A photographic film of satisfactory flexibility and free from brittleness comprising a cellulose organic acid ester support and a photographically sensitive colloid layer adhesively joined to the support by a composite intervening layer comprising an extremely thin sub composed of a glyptal resin and a gel sub adhesively joined to the resin sub and to the sensitive colloid layer, said intervening layer rendering the flexibility characteristics of the film as a whole independent of the degree of adhesion existing between thephotographically sensitive layer and the subbed support.

14. A photographic film of satisfactory flexibility and free from brittleness comprising a cellulose organic acid ester support and a photographically sensitive colloid layer adhesively joined to the support by a composite intervening layer comprising an extremely thin sub composed of an alkyd resin and a gel sub adhesively joined to the resin sub and to the sensitive colloid layer, said intervening layer rendering the flexibility characteristics of the film as a whole independent of the degree of adhesion existing between the photographically sensitive layer and the subbed support. 6

15. A flexible photographic film comprising a cellulose organic derivative support layer, which layer, if uncoated, would have flexibility under dry conditions, a photographic colloid layer carried by the support and having the characteristic of becoming brittle in conditions under which the support remains. flexible, and a sub layer between the photographic layer and the support layer and adjacent the support layer, all the said layers being strongly adherent to one another, the'sub layer comprising a polybasic acid-polyhydric alcohol resin and rendering the film permanently highly flexible.

16. A flexible photographic film comprising a. cellulose organic derivative support layer, which layer, if uncoated, would have flexibility under dry-conditions, a photographic colloid layer carried by the support and having the characteristic of becoming brittle in conditions under which the support remains flexible, and a sub layer between the photographic layer and the support layer and adjacent the support layer, all the said layers being strongly adherent to one another, the sub layer comprising the resinous reaction product of a mixture of polybasic acid, an alcohol having three or more hydroxyl groups in the molecule, a dihydric alcohol, and a dibasic acid, and rendering the film permanently highly flexible,

1'7. A photographic film of highflexibility and free from brittleness, comprising a cellulose organic derivative support and a photographically sensitive colloid layer adhesively joined to the support by a composite intervening layer comprising a thin polybasic acid-'polyhydric alcohol resin sub adhesively joined to the support and a. gel sub adhesively joined to the resin sub and to the sensitive colloid layer, said intervening layer rendering the flexibility characteristics or the film as a whole independent of the degree of adhesion existing between the photographically sensitive layer and the'subbed support.

18. A photographic film of high flexibility and support by a composite intervening layer comprising a thin resin sub composed of a resinous reaction product of a mixture of a polybasic acid,

an alcohol having three or more hydroxyl groups in the molecule, a dihydric alcohol, and a dibasic acid, said sub being adhesively joined to the support and a. gel sub adhesively joined to the resin sub and to the sensitive colloid layer, said intervening layer rendering the flexibility characteristics of the film as a whole independent of the degree of adhesion existing between the photographically sensitive layer and a subbed support.

- GALE F. NADEAU.

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