US584862A - George eastman - Google Patents

Description

learn STATES PATENT FFICE.

GEORGE EASTMAN, OF ROCHESTER, NEW YORK, ASSIGNOR, BY MESNE AS:

SIGNMEN'lfi-TQ THE EA S'lhlAN KODAK COMPANY,

OF SAME FLA-C MANUFACTURE osPHoToeRAP'mc FILM.

SPECIFICATION forming part of Letters Patent No. 584,862, dated J is 22, 1897.

i Application filed February 15,1892.

1'0 all whom it may concern:

Be it known that I, GEORGE EASTMAN, of Rochester, in the county of Monroe and State of New York, have invented certain neiv and 5 useful Improvements in Photographic Film and Methodsof lilanufacturingthe Same; and

I do hereby deciarcthe following te b' such a full, clear,and exact description of the same as will enable one skilled in the art to prac- TO tice the invention. 7 p

In the manufacture and use of photographic film such is now ingeneral use, consisting of a base or support of a nitrocellulose or similar compound, provided with a sensitive r5 coating of gelamndargentic"emulsion, a considerablc difficulty has manifested itself and large quantities of film-have been rendered worthless by reason of the streaks ormarkings found in the sensitive coating upon de- 20 velopment, caused by the sparks or electrical discharges produced when the him is rolled or unrolled in the roll-holders used for carryingitin long lengths, and also oftentimes during its manufacture and subsequenttreat- 2 5 ment, as when out into'strips or wound on the spools. These discharges manifest themselves as sparks, which are sufficiently bright to fog the sensitive emulsion in lines resembling discharges of static electricity, as seen, o-for instance, in flashes of lightning or discharges from a static electrical machine. Of

course when thefilm is in this way practieally exposed during manufacture it is ren- 0 is therefore the object of my present invention to obviate this difliculty and prevent the formation of these sparks or discharges by rendering the iilmsupport non-electric, so

to say, by the addition to it of a suitable 1nate= 4 5 rial which will not affect to any appreciable ex-' tout the quality of the support as, a supporte that is, will not render it too opaque for pho tographic uses byprecipit-atin g any of thsub- Serial No 421,626. No specimens.)

or coloring it, nor. affect the sensitiveness of the emulsionv applied to it.

After considerable experimenting I have discovered that ifa small quantity of a me, tallic salt possessing the above characteristics and soluble in the solvents of nitrocellulose,

tassiu'nr nitrate or ammonium nitrate, ;,be added to the emulsion support the latter is" thereby rendered non-electric, and the obj ectionablc electrical manifestations will be premaking film described in Letters Patent No. 4717,2022, granted December 16,1889, tothe Eastman Dry Plate and Film Company, is practiced, said method consisting in depositing or spreading a nitrocellulose compound upon a plate-glass support, the emulsion bethe support.

hen making film according to this patent, I prefer to incorporate in the nitrocellunitrate, the proportion of which I have used with success being about ten (10) grains to the pound, but it is obvious that a larger or cient quantity to aifeet the quality of the film or the filmsupport.

In Letters Patent No. 441,881, granted to me December 2, 1890, l have described an improvedfilm consisting of a nitrocellulose support sealed between two'gelatin coatings, one of which is the emulsion, said film being made by depositing upon a plate-glass table or support, first, a gloating of insoluble gelatin, then a nitrocellulose compound, and finally the sensitiveemulsion, the whole when making this film also .a considerable'aniount isrende'red worthless by the electrical discharges produced w en it is stripped from the glass which, however; can be prevented preferably one of the alkali nitrates, as'Zpo-i vented both during the manufacture of the film, its subsequent treatment, and when used in roll-holders. flhese discharges or sparksv are particulary apparent when the method of ing afterward applied or coated upon it and the whole after. drying being stripped from lose compoundasmall quantity of ammonium smallerlamount could be used if not in sufii stances therein,being precipitated by them,

drybeing stripped from theglass, and in r by adding to the solution of gelatin that is tassium nitrate, and I have used with success about fifty (50) grains to the pound, but, as before stated, a greater or less amount such as would not affect thev quality of the film may be employed.

' As the proportion or the other ingredients.

employed in both the nitrocellulose compounds and the gelatin and the apparatus and manipulations necessary'to manufacture the film have been described in the beforementioued patents and other applications now pendingat-the Patent Office, it is deemed unnecessary herein to specifically describe.

the same.

Thefilm produced by my invention, having what I term a non-electric support, is found to be practically free from the electrical markings and can be wound and unwound and used in roll-holders of the usual or any preferred construction in long lengths withoutliability of being damaged from these causes, and small sheets or detached pieces of photographic film, the supports of which are rendered non-electric, either during the methods of manufacturingj'usfdescribed or when manufactured by other methods,'can be used without liability of being affected in an objectionable manner] lVhile I have described one method of manufacturing my improved film and one material that can be used with. success, I do not wish to be confined to either of these, as a number of other substances producing the samc'results can be used and other methods of manufacture employed.

I claim as my invention 1. As an article of manufacture, a photographic film consisting of a non electric transparent or translucent support containing a nitrocellulose compound and a superposed coating sensitive to the action of light, as set forth.

2. As an article of manufacture, a flexible photographic film consisting of a flexible transparent or translucent support composed of a nitrocellulose compound containing an inorganic salt soluble in'nitrocellulose solvents, as methyl alcohol, and a superposed gelatino-argentic emulsion, as set forth.

3-. As an article of manufacture, afiexible photographic film consisting of a flexible sup.- portcomposed of a nitrocellulose compound containing an alkali nitrate and a superposed gelatino-argent-ic emulsion, as set forth.

4. As an article of manufacture, a flexible photographicfilm consisting of a flexible support composed of a nitrocellulose compound containing ammonium nitrate and a superposed gelatino-argentic-emulsion, as set forth.

5. As an article of manufacture, a flexible photographic film consisting of a flexible support composed in'part of a nitrocellulose compound an rendered non-electric and a superposed gelatino-argentic emulsion, as set forth.

6. In the method of. manufaoturingsensitive photographic film involving the deposit upon a vitreous support of a fluid substance which when dry forms the support for the sensitive emulsion, and the subsequent stripping of the complete film from the vitreous support, the improved. step consisting in rendering the emulsion support non-electric whereby when the film is stripped from said support electrical discharges and the consequent fogging of the film are prevented, as set forth.

7. The method of manufacturing transparent or translucent sensitive photographic film consisting in adding to a fluid nitrocellulose compound, which when. dry forms the support for the sensitive, emulsion, a quantity of an inorganic salt soluble in the solvents of nitrocellulose, as methyl alcohol, and which will not precipitate any of the materials of the compound, nor be precipitated by them, spreading said fluid compound upon a vitreous support, then drying it, then spreading a sensitive emulsion thereon, and drying it, and finally stripping the complete film from the vitreous support, as setforth.

8. The method of manufacturing sensitive photographic film consisting in adding to a fluid substance, which when dry forms the Support for the sensitive emulsi0n,a quantity of an alkali nitrate soluble in the solvents of said substance, spreading said fluid substance upon a Vitreous support, then drying it, then spreading a sensitive emulsion thereon, and drying it, and finally stripping the complete film from the support, as set forth.

0. The method of manufacturing sensitive photographic film consisting in adding to a fluid nitrocellulose compound which when dry forms the support for the sensitive emulsion, a quantity of ammonium nitrate. then spreading said compound upon a vitreous support and drying it, then spreading a sensitive emulsion thereon and drying it, and finally stripping the complete film from the vitreous support, as set forth.

10.' In the method of manufacturing scnsione, FASTMAN.

Witnesses .llonacn hlCGljlllE, Flilfl CHU'nrn.