US2337345A - Method of promoting the adherence of cellulose ester emulsions onto film bases - Google Patents

Description

Dec. 21, 1943. w. 'PARTRIDGE. JR 2,337,345

METHOD OF PROMOTING THE ADHERENCE OF CELLULOSE ESTER EMULSIONS ONTO FILM BASES Filed March 5, 1942 Fllll.

SILVER HALIDE-CELLULOSE ESTER EMULSION (APPARENT ACETYL 21.5%) CELLULOSE ZSZAP OF3I.9% APPARENT ACETYL ESTER SUB{ 75,LAP 0F 29.61- n CELLULOSE {zszAP OF 29.6% APBARENT ACETYL ESTER SUB 757. AP CF 32.6% I

CELLULOSE EsrER SUPPORT (401, APPARENT ACETYL)- FIE-1.2.

SILVER HALlDE-CELLULOSE ESTER EMULSION (APPARENT ACETYL 2:57

CELLULOSE 701 AP OF 3|.9Z APPARENT ACETYL ESTER SUB 307 AP CF 28.2%

CELLULDSE 491 AP 0F 35.7% APPARENT ACEJTYL ESTER sue 517. AP OF 29.974

cELLuLosE ESTER SUPPORT(40'Z APPARENT ACETYL) W! NFIELD PARTRIDBEHJRJ INVENTOR ATT EYS Patented Dec. 21, 1943 METHOD OF PROMOTING THE ADHERENCE OF CELLULOSE. ESTER. EMULSIONS ONTO FILM BASES Winfield Partridge, Jr., Rochester, Y., assignor to Eastman Kodak Company, Rochester, N. Y.,

a corporation of New Jersey Application March 5,1942, Serial No. name 11 Claims. .(Cl. 95-9) use as the carrier for the silver halide. Not only This applicatipn relates to the subbing of photographic film having thereon cellulose ester "photographic emulsions to cause the adherence of those emulsions to the cellulose ester film base.

Recently the use of far-hydrolyzed cellulose esters, as carriers for the silver halide in photographic emulsions, has been described and claimed in U.- S. Patent No. 2,110,491 of Salo. This patent points out that photosensitive emulsions, using acetyl cellulose esters particularly those having anacyl content of -28%, are eminently suitable for use in the photographic in dustry. The adherence however, of these emulsions is pogrwhen applied to a film base of an organic acid ester of cellulose and exhibits a tendency'to pull away at the edges during coating and to exhibit poor adherence to the film base during the processing operations. Also, there is a tendency for these emulsions when supported by film base of an organic acid ester of cellulose to form blisters when treated in the conventional acid fixing baths.

These characteristics have interfered heretofore with the use of cellulose ester emulsions for the preparation of photographic film.

One object of my invention is to provide a method of aifixing cellulose ester emulsions to cellulose organic acidester film base, wherebypulling, sliding, blistering and dry stripping of the emulsion layer from the film base, is elim-.

inated. Another object of my invention is to provide a gelatin-free photographic film having good permanence in ordinary use. Other objects of my invention will appear herein.

I have found that far-hydrolyzed cellulose organic acid ester emulsion layers can be attached do cellulose esters employed for the photographic emulsions difler from those employed for the photographic film base in the degree of hydrolysis, but also in many'instances the. composition -,oi acyl in the film baseester difiers from that of the ester employed as thecarrier for the silver halide. This invention is primarily concerned with the preparation. of photographic film in which the acyl of the cellulose estersemplcyed essentially consists of fatty acid radicals of 2-4 carbon atoms. The far-hydrolyzed cellulose ester employed as the carrier for the silver halide in the emulsion may be a water-susceptible cellulose acetate such as one having an acetyl content between .20 and 28%, while the cellulose ester employed in the film base may be a cellu-- lose acetate having a' relatively high acetyl content (such as-38-42 or a cellulose acetate propionate or a cellulose acetate butyrate which may be substantially fully esterified or which maybe hydrolyzed to some extent but not enough to appreciably diminish the Water resistance of the ester when formed intojsheeting. Instead of using. a straightacetate, the cellulose ester employed, as the carrier for the silverhalide, may be a water-susceptible cellulose acetate propionate which has been hydrolyzed down to an acyl content between 20 and 28%. To coat this emulsion upon a water-resistant film base-would, to obtain good adherence,- necessitate intermediate subbing coatings.

,The accompanying drawing illustrates photographic film in accordance with my invention.

to cellulose organic acid ester film base', if inter-' mediate subbing layers are employed consistingof cellulose estershavingacyl contents gradu-' ated between the cellulose ester of the emulsion layer and that of the cellulose ester employed for the film base. Itis pointed out in, the Salo pat- .ent, referredto above, that the cellulose esters employed for the photographic emulsion should be of a water-permeable nature in order to assist;

the processing of the silver halide emulsion. Cellulose esters,-which are employed for film base,

- on the other hand, should be resistant to Water so as to support a photographic emulsion during the processing operation andalso to form a surface which is unaffected by water when the emulsion is coated thereon; In order to obtain a film base having these characteristics, a cellulose ester must be employed having properties dissimilar to those of the cellulose ester which is suitable for Figure I iilustratesa photographic film composed of a film support in which the cellulose ester is a cellulose acetate propionate having an acetyl content of 29%, a propionyl' content of 14.5%

,and an apparent acetyl content of 40%, 3 subbing layers of the indicated acyl contents and an emulsion layer as shown. Figure 2 illustrates a photographic film in which only 2 subbing layers are employed. a u f By employing cellulose esters for the subbing layers, having characteristicsas regards hydrolysis and as regards acyl composition substantially intermediate between theester employed for the emulsion and that employed for the film base, good adherence of the emulsion to the film base is obtained and absence of stripping may be effected. I have also found that the number of subbing layers may be substantially decreased ,if a mixture of twoormore estersis employed for each subbing layer. Where a mixture of esters is employed the difierence between the ap- Between film base and adjacent subbing Between parent acetyl contents of the' cellulose esters in each subbing layer should be no more than 9%. It is desirable to employ a sufiicient number of subbing layers that good adhesion is obtained between the film base and the emulsion. I have found that there is seldom any casein ordinary practice with cellulose ester emulsions and cellulose ester film base where more than three intermediate or subbing layers are required and, as a general rule, two subbing layers will b sufiicient, particularly if mixtures of esters are employed in each subbing'layer, although the use of a greater number of subbing layers is within the scope of tent of the subbing layer adjacent thereto should be no morethan 11%. Also, in accordance with my invention, it isdesirable that the average apparent acetyl content of any subbing layer be no more than 3 /z% different from thatof any ad'- jacent subbing layer. The average apparent acetyl content ofthe subbing layer adjacent the emulsion layer should be no more than 12 percent the am base ester and of the emulsion ester,

as described herein. These layers may be deposited from appropriate solutions by any *meth od known to those skilled in the art, such as by immersion, beading or the like, the support, being passed through or in contact with the solution at r such a rate that a layer of the desired thickness will be laiddown on the material. In general, these subbing layers are not morethan a few one hundred thousandths of an inch in thickness (such as .000025 in. thick) although thicker layers may be applied in any case where excessive thickness is not objectionable. After each application of a subbing solution, the support is subjected to an appropriate drying operation at atemperature sufiicient to evaporate the solvent.

Many different subbing layers of cellulose ester may thus be deposited upon the film support prior to applying the emulsion thereto.

The following examples illustrate my invention: r Example I A film base having a thickness of approximately'..005 in.,prepared by coating out a solution of a slightly hydrolyzed cellulose acetate propionate, having an acetyl content of 29% and a propionyl content of 14.5% (apparent acetyl 40%) and a plasticizer, from propylene chloridedifferent than the apparentacetyl content of the cellulose ester of the emulsion. In the preferred embodiment of my invention, it is desirable that the apparent acetyl contents differ as follows:

/ Per cent layer About6 Between adjacent subbing layers About 2 emulsion andadjacent subbing layer About '7 The cellulose ester emulsions to which my invention is applicable are those described and claimed in the Salo Patent No. 2,110,491, referred to herein; The film base to which my invention is applicable is any base prepared from a lower 'fatty'acid'ester of cellulose in which theacyl consists of fatty acid radicals of 2-4 carbon atoms. For example, the film base prepared by coating out a slightly-hydrolyzed cellulose acetate propionate and a plasticizerfrqm propylene chloride-alcohol, as described and claimed in Malm Patent ,No. 1,960,185, would be quite suitable for ,use herewith. The film base might be a cellulose propionate or cellulose butyrate or even a cellulose triacetate. .In preparingthe film base, a solution of the cellulose ester is coated out onto a film-forming surface as a transparent layer, the

composition containing, inaddition to the cellulose ester, a .plasticizer such as triphenyl-phosphatein small amount and a volatile solvent v therefor such as acetone, ethylene chloride or propylene chloride-methyl alcohol.. It is preferred that the conditions of coating be so contained. There is then deposited on this film base alcoholas described and claimed in Malm Patent No. 1,960,185, dated May 22, 1934, was coated with an extremely thin coating consisting of a mixture of two cellulose acetate propionates A and B,

ester A which made up 40% of the mixture having an acetyl content of 24.4%, apropionyl content of 13.9% and ester B which made up of themixture having an acetyl content of 22.5% and a propionyl content of 12.8%. The layer was coated out on to the film base from a 2% solution of the ester mixture in a solvent composed of acetone 28%, methanol 62% and cellosolve 10%.

After the first subbing layer on the film base had set anddried, a second layer was applied thereover consisting of a ire of two cellulose acetate propionates A am. B, ester A which comprised'75% of the mixture having an acetyl content of 22.5% anda propionyl content of 12.8%, and ester B which made up 25% of the mixture having an acetyl content of.20.8% and a propionyl content of 12.6%. After this subbing layer had set and dried, a third subbing layer trolledthat,"after evaporation of the solvent and the curing of the'film, a sheet or film of cellulose ester, approximately .005-.010 in. thick. is, ob-

or film support a series of extremely thin layers of lower fatty acid esters of cellulose or preferably mixtures of these esters having characteristics intermediate and graduated between those of.

was applied thereover. j This layer consisted of a mixture of two cellulose acetate propionates A" and B", ester A" which made up 25% of the. ,mixture having an acetyl content of 19.8% and a propionyl contentof 14.6%, and' ester B" which made up of, the mixture having an acetyl contentof 20.8% and a propionyl content of 12.6%. Both, the second and third layers were respectively. coated from 2% solutions of the mixture of .the cellulose. esters in a solvent having 'the same composition as employed in applyin the first subbing layer. This solvent composition can be varied, however, as desired by the individual operator or, if desired, other suitable solvent compositions may be employed. I

After the last subbing layer had set and dried, a photographic emulsion layer wasapplied thereto. ,The photographic emulsion was made, up of silver halide carried by, a far-hydrolyzed cellulose acetate propionate having an acetylco'ntent of 15.2%, a propionyl, content of 7.9% and an apparent acetyl content'of 21.5%, dissolved in a solvent mixture consisting fof'49%. ethyl alcohol,

49% water and 2% monoacetin. The emulsion -may, if desired, contain a sensitizing dye or any other added materials to impart the desired properties thereto. Theemulslon layer was dried thus giving a photographic film which is readilysusceptible to developing and fixing in the usual manner. i

Example II Toa filrn base the same as employed in Example I, a layer was applied consisting of approximately equal parts of two cellulose acetate propionates, one having an acetyl content of 23.3%

- and a propionyl content of 16.5% and the other an acety'l content of 19.8% and a propionyl conl tent of 12.8%. -.'ery dilute solution in organic solvents such as This layer was applied from a employed for the same purpose in the preceding example. After the subbing layer had set and dried, a second layer was applied thereto consisting of a mixture of two cellulose acetate p'ropionates, one which made-up 70% of the mixture having an acetyl content of l9.8%- and a propionyl contentof 14.6%, and the second which.

made up the remainder of the mixture having an acetyl content of 20.7% and a propionyl content of 10.4%. After this subbing layer had dried, it

photo-sensitive emulsion layer was applied there-lto of the same nature and in the same manner as described in,thepreceding example.

Example IZ I To a film base, the same as employed in Example I, a'thin layerwas applied consisting of 58%-0f a cellulose acetate propionate having an acetyl content of 23.3% and a'propionyl'content of.16.5% and of 42% of a cellulose acetate propionate having an acetyl content of 19.3% and a propionyl content of 12.1%. This layer was coated out onto the'film base from a.2% solution of the ester mixture in the same solvents as employed for that purpose in Example I.- After the The term apparent acetylff as employed herein, refers to the acyl content-of the cellulose ester figured in terms of acetyl. For instance, if a cellulose ester was a diester containing one butyryl group for every acetyl group therein,-the apparent acetyl would be the same as if both of the acyl groups were acetyl or, in other words, would be the same percentage as the acetyl content of a cellulose di-acetate. The term .average apparent acetyl content refers to the average apparent acetyl content of a cellulose ester composition. If the'composition consists substantially of all the same ester,. obviously the apparent acetyl content and the average apparent acetyl content is substantially the same. However, if .the composition consists of a mixture of esters, the average apparent acetyl. content will be the average of the apparent acetyl contents of each of the esters present, weight being given the apparent acetyl content of each ester in accordance with the proportion of that ester which ispresents For instance, if a'composition consists of 75% of a cellulose ester having an apparentacetyl con tent of 34 and 25% of a cellulose ester having an apparent acetyl content of the average apparent acetyl content of the composition will be approximately 33%.

Anyone familiar with cellulose esters would be able to supply photographic film of the type reefrredto in accordance with my invention. How ever, analternative method, which might be employed for preparing a photographic film in ac- 'cordance withmy-invention, would be to depend subbing layer had set and was. dried, a photographic emulsion layer was applied thereto, which layer was made up of silver halide carried by a far-l'iydrolyzed cellulose acetate 'propi'onate having an acetyl content of 15.2%, a propionylcontent of 7.9% and an apparent acetyl content of 21.5%, coated out from a' solvent mixture contaim'ng ethyl alcohol and water in equal amounts. The emulsion layer was dried and there'resulted a photographic V -Example IV A. film base prepared by coating cut a solution of a slightly hydrolyzed cellulose acetate butyrate,

having an acetyl content of 30% and a butyryl content of 17 was coated with an extremely thin coating consisting-of a mixture of equal parts of two cellulose acetate butyrates, A and B,

ester A having an acetyl content of 28.9% and a butyryl content of 13% and ester B'having an acetyl content of 27% and a butyryl content of 7%. This layer wasappliedfrcm dilute solution in a mixture of organic solvents. After this subbing layer had dried, it was coated with a second layer consisting of a. mixture of .equal parts of two cellulose acetate butyrates, A' and B, ester A having an acetyl content of 28.3% and'a butyryl content of 11% and ester B having an acetyl content of 26% and a butyryl content of 5%. After this subbing layer had dried, a photosensitive emulsion layer, in which the emulsion vehicle was a cellulose acetate of 25% acetyl content, was applied thereto as described in Example I.

. a propionyl content of 4 upon triangular graphs, such as shown in the prior art, for instance, in Malm Patent No. 2,078,- 261, dated April 27, 1937. For instance, suppose the preparation of a photographic film was desired in which the cellulose ester in the emulsion 'to beused was a cellulose acetate having an terms of apparent. acetyl and the distance between the emulsion layer point and the first point on'the line after that should be no more than 12% figured in ter'msirif apparent acetyl. The intermediate points should be much closer together so-that they are no more than 3%%- different figured as apparent acetyl.

It is preferable for the subbing layers that a mixture of cel-- lulose esters be used, selected by taking alternative points for the esters which are to'be mixed.

In that case the points adjacent the emulsion ester. and film base ester points would 'obviously' be selected less than 12% and 11% respectively from the latter points so that the average apparent'acetyl contents of the layers are within the terms of .my invention. ,It has been my experience that by using a mixture of esters better results are obtained. With a line between the 'points, designating the emulsion ester and thefilm baseester, anyone, even though unfamiliar with cellulose esters, can easily select a series of esters for subbing layers in accordance with the instructions in this description which will cause good adherence between the film base and the organic acid ester and thereb'etween at least one cellulose-organic acid ester subbing layer the acyl contents of which are graduated between the cellulose ester of the emulsion layer and that of the film base, the difierence between the apparent acetyl content of the cellulose ester of the film base and the average apparent acetyl content of the subbing layer adjacent thereto being no more than 11%, the difierence between the average apparent acetyl contents of any subbing layers adjacent to each other being no more than 3%;%,

the difference between the apparent acetyl content of the cellulose ester in the emulsion and the average apparent acetyl content of the subbing layer adjacent thereto being no more than 12% and the difference between the apparent acetyl difierence between the apparent acetyfcontents of substantially all of the cellulose esters in eachsubbing .layer' being no more than 9%.

high water resistance, an emulsion layer containr t. A photographic comprising a film base layer comprising a cellulose-organic 'acid ester of such relatively high' acyl content that it has ing as the protective colloid a far-hydrolyzed cellulose-organic acid ester and therebetween a plurality of subbing layers made up of mixtures of celluloseesters, the average acyl contents of the subbing layers being graduated between the cellulose esters of the emulsionlayers and that of the filmbase, the diflference Between the apparent being no more than.3 /2%, the diflerence between the'apparent acetyl content of the cellulose ester in the emulsion and the average apparent acetyl content of the subbing layer adjacent thereto i being no morethan 12% and the difference be- 5. A photographic .film comprising contents of substantially all of the cellulose; es-

ters in each subbing layer being no more than 2; A photographic film comprising a-film base layer comprising a cellulose-organic acid ester of suchrelatively 'high acyl content that it has high water resistance, an emulsion layer containing as the protective colloid a far-hydrolyzed cellulose-'- organic acid ester and therebetween afplurality of cellulose-organicacid estersubbing layers, the

tween the apparent acetylcontents of substantially all of the cellulose estersin each subbing layer being-no more than 9%., v q i .a film base layer -,..comprising a cellulose-organic acid ester of such relatively high'acyl content that it has high water resistance, an emulsion layer containing as the protective colloid a far-hydrolyzed cellulose-organic acid ester and therebetween at least.one'cellulose-organic acid ester subbing layer the acyl-rbntents of which are graduated betweenthecelluldse ester of .the emulsion layer andxthat of-theifilm base, the difference between acyl contents of which are graduated between thecellulose ester of the emulsion layer and that of the film base, the difference between the apparent acetyl content of the cellulose ester'oi the film of the filmbase and the average apparent acetyl being approximately-6%, the difierence between the average apparent acetyl contents oi'thesubbase and theaverage apparent aeetyl content of the subbing layer adjacent thereto being no more than 11%, the difference. between the average bing layers adjacent to each other being approxinmately 2% and the difierence between the apapparent acetyl contents of any} 'subbing .layers.

adjacent to each other being no more than 3 2%,

' the difference between the apparentacetyl content of the cellulose'ester in the emulsion and the average apparent acetyl content oi the subbin -layer adjacentthereto being no more than 12% and the difference between the apparent acetyl contents of substantially all of the cellulose esters in each subbing layer being no more. than;9

3. A photographic film comprising afilm base layer comprising a cellulose-organic acid ester parent-acetylcontent of--the. celluloseester in the emulsionwand the average apparent acetyl content of the subbing. layer adjacent'thereto being approximately 7% .and the difference betially all-the cellulose ester-sin each: subbing layer being approximately 7%.;

of such relatively high acyl- -co n tent thatfit has high water resistance; emulsion layercon- 6. A photographic filmcomprising a filmfbase layer comprising acellulose-organic acid ester of such relatively high acyl content that it has ".high water resistance, an emulsion: layercontaining as the protective colloid' aifar liydrolyzed cellulose-organic acid ester and'therebetween a phi- I rality of cellulose-organio-acid' ester subbing laytaining as the protective colloid a far-hydrolyzed I cellulose-organic acid ester and therebetween subbing layers made up of amixtureof. cellulose 3' that 0f the -b the ence between esters, the acyl contents of thdsubbing ayers being graduated between the cellulose ester of theemulsion' layer and that of the film base, the diilerence between the apparent acetylcontent of lulose ester in the emulsion and-the average apparent acetyl content of the subbing layer-adjacent thereto being no more than 12% andthe the cellulose ester of the filmbase and'the averers,'the acylcontents-ot which are-graduated between the cellulose ester-oftheemulsion layer the apparent-acetyl content of-theicellulose ester of the filrnbase. andthe average. apparent acetyl content-of the, subbinglayenadjacent thereto "parent acetyl 'content oi the cellulose ester in the emulsion and the average apparent acetyl content of the subbing layer adjacent thereto be- 7 ing approximately 7% and thedifference between the apparent acetyl contents '0': substantially all the cellulose esters in each sfibbing layer being pprox mate y, v

aasasss age apparent acetyl content of the subbing layer adjacent thereto being approximately 6%, the difference between the average apparent acetyl contents of the subbing layers adjacent to each other being approximately 2% and the difference between the apparent acetyl content of, the cellulose ester in the emulsion and the average apparent acetyl content of the subbing layeradjacent thereto being approximately 7% and the" difierence between the apparent acetyl contents of substantiallyall the cellulose esters in each I subbing layer being approximately 7%. Y

8. A photographic film comprising a, film base layer comprising a cellulose-organicvacid ester 'of such relatively high acyl content that it has high water resistance, an emulsion layer containing as the protective colloid a far-hydrolyzed cellulose-organic acid ester and therebetween a plurality of subbing layers made up of mixtures of cellulose esters, the average acyl contents of the subbing layers being graduated between the cellulose esters of the emulsion layers and that of the film base, the difierence between the apparent acetyl content of the cellulose ester of the film base and the average apparent acetyl con-' tent of the subbing layer adjacent thereto being approxima 1y 6%, the difierence between the average apparent acetyl contents of the subbing layers adjacent to each other being approximately 2% and the difference between the apparent acetyl content of the cellulose ester in the emulsion and the average apparent acetyl content of the subbing layer adjacent thereto being approximately 7% and the difierence between the apparent acetyl contents of substantially all'the cellulose esters in 'each subbing layer being approximately'7%.

9. A photographic film comprising a cellulose acetate film base layer having a relatively high acetyl: content, an emulsion layer containing as the protective colloid a far hydrolized cellulose acetate and therebetween at least one cellulose acetate subbing layer, the acetyl contents of which are graduated between the cellulose acetate of the emulsion layer and that of the film base, the difference between the acetyl content of the cellulose acetate of the film base and the acetyl content of the subbing layer adjacent thereto be-- mg no more than 11%, the difference between the acetyl contents of any subbing layers adjacent to each other being no more than 3 the difference between the acetyl content of the cellulose acetate in the emulsion and the acetyl content of the subbing layer adjacent thereto being no more than 12% and the difference between the acetyl contents of substantially all of the cellulose acetates of each subbing layer being no more than 9%.

10. A photographic film comprising a cellulose acetate propionate film base of such relatively high acyl content that it has high water resistance, an emulsion layer containing as the protective colloid a far hydrolyzed cellulose acetate propionate and therebetween at least one cellulose acetate propionate subbing layer, theacyl contents of which are graduated between the-cellulose ester of the emulsion layer and that of the film base, the difference between the apparent acetyl content of the cellulose ester of the filmvbase and the average apparent acetyl content of the subbing layer adjacent thereto being no more than 11%, the difference between the average apparent acetyl contents of any subbing layers adjacent to each other being nom'ore than 3 /2%, the difference between the appar ent acetyl content of the cellulose ester in the emulsion and the average'apparent acetyl con:-

tent of the subbing layer adjacent thereto being no more than 12% and the diflerence between the apparentacetyl contents of substantially all of the cellulose esters in each subbing layer being no more than 9%. v

11'. A photographic film comprising a cellulose .acetate -butyrate film base layer of such relatively high acyl content that it has high water resistance, an emulsion layer containing as the protective colloid a far hydrolyzed mixed organic acid ester of cellulose and therebetween at least one cellulose mixed organic acid ester subbing layer, the acyl contents of which are graduated between the cellulose ester of the emulsion layer and that of the film base, the difierence between the apparent acetyl content of the cellulose ester of the film base and the average apparent acetyl content of the subbing layer adjacent thereto,

tween the apparent acetyl contents of substantially all of the cellulose esters in each subbing layer being no, more than 9%;

WINFIELD PAB'I'RIDGE, JR.-

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