US1807809A - Composition fob imbibition printing - Google Patents

Description

Patented June 2, 19%

sii oFIcE BERTHA SUGDEN TUTTLE, OF BOSTON, MASSAGHUSETTS, ASSIGNOR T0 TECHNIOOLOR MOTION PICTURE CORPORATION, 015 BOSTON, MASSACHUSETTS, A. CORPORATION OF MAINE No Drawing. Original application filed April 30, 1926, Serial No. 105,861.

filed May 27, 1927.

This invention relates to the preparation of colored reproductions, especially upon transparent surfaces such as gelatine or the like, and to the resulting product.

In the art of preparing colored reproductions, especially upon absorptive surfaces such as gelatinous films and coatings, it has heretofore been proposed to print such surfaces from hardened films, or matrices socalled, which bear the developed image or complemental portions of the image to hereproduced. This processdepends upon'the selective wetting of the developed areas of the matrix film (which may also stand in relief) by the dye solution and the non-wetting of the undeveloped areas. It also depends upon the direct transfer of the dye as thus distributed to a relatively soft gelatinous surface,which takes place upon efiecting intimate contact between the two surfaces,-by imbibition. Hence this general method of procedure is known in the art of color photography as an imbibition process.

In the practical application of this procedure even though the film printed is opaque and the reflected colors only are desired, it is found difficult to secure and maintain accuracy of registry, relative color values, definition, and like characteristics. When the reproductions are made upon transparent materials, however, and are intended for projection purposes as in cinema films, the relative depths and contrasts of the several shadesand tones of coloration produced upon and in the surface (with respect to their several and composite light transmission values?l also become of primary importance. In suc instances it is necessary that the coloring agents (usually dyes) shall not only be proportionately and accurately distributed with respect to their relative color Values and contrasts upon the matrix, but that they shall also be quickly and accurately transferred and fixed to the printed filmisurface.

It is further important that the relative contrasts or shades of a given color when thus transferred t p the printedfilm shall manifest themselves with respect to transmitted light according to the corresponding contrastspr degrees of development of the COMPOSITION FOR IMBIBITION PRINTING- Divided and this application Serial No. 194,853.

several portion-s of the image upon the matrix film. When two or more colors are to be used, it is essential that they be mutually inert in order that their several and composite color values shall be maintained and shall not be deleteriously affected or altered. Accordingly it is an object of the present invention to provide a method for the preparation of colored reproductions, astypified by the more exacting application to cinema I films, whereby the conditions above set forth may be satisfied anda product obtained of such qualities and characteristics as shall successfully adapt it to its intended use. Other and more specific objects of the invention will appear from the following disclosure.

It is found, as a part of the present invention, that whereas a matrix film may be developed to present degrees of density or contrast corresponding to the complete range of the & DJ) scale, these gradations may not be reproduced by corresponding intensities or concentrations of a dye solution adsorbedupon them, or, if such relative distribution of dye is accomplished on the matrix, that it is not preserved and maintained in the image which results upon" transferring the dye to the second relatively soft gelatine sur-- by the addition of albumin oriotheramphoteric colloid thereto, followed by the coagulation and removal of the colloid, together with those components of the dye which are susceptible to precipitation or selective segregationiupon contact with a surface such as the gelatine matrix.

The dye solution so treated is more uni- .formly distributable over the developed matrix surface and is adsorbed thereby more nearly in proportion to the relative contrasts or degrees of development which it presents. Moreover, it is susceptible of being completely-transferred from the wet matrix to the soft, gelatine surface, by imbibition, and consequently a wider range of color values and contrasts is made possible in the printed image produced. 1 It is also found that this surfaces as distinguished from those which are adsorbed by and adhere to the free surface of the gelatine' only or are unequally penetrative thereof.

It is well recognized that in general acid dyes are more suitable than basic dyes, and

cable, however,

it has also been observed, Lemaire Brit. J our. Phot. 1911, 58, 969 and Curtis and Lemoult, Compt. Bend. 1905, that sulfonic acid dyes take more actively upon gelatine, in proportion to the'number of sulfonic groups which they contain. Accordingly,*such dyes may be descriptively designated as gelatine penetrative dyes, and While many of them may not be suitable for the purpose of dyeing transparent films on account of other and undesirable attributes, they may be considered, in the aspect of penetrability and resultant contrast effects upon gelatine surfaces, as fundamentally appropriate coloring agents.

It may here be remarked that in colored transparent films where the transmitted light eflect obtained by'a given dye is due to its absorption of the remaining elements of the spectrum, it is essentially desirable that through an area of any given color, for example an area containing a single dye, the transmitted color shall be of the specifically appropriate portion of the spectrum and that the absorption of colors in other portions of the spectrum shall be complete, or substantially so, in this area. It is further desirsuch areas shall not be reduced in intensity except in proportion to the contrast or shade of the transmitted color which is desired.

It is a characteristic of most dyes that when color contrasts are sought to be obtained therewith corresponding to the deeper shades of the transmitted colors, (for examge, optical density of 2.0 ormore on the & D. scale,) they are visually indistinguishable. This is probably due to total light bsorption or reduction of light intensity in- -stead of selective absorption of other spectral opaque formation.

colors only and the continued transmission of the color of the dye. This may also be caused by a concentration of the dye substance at or near the surface in a concentrated and resultingly solid and relatively The shades of red, for depth of color correspondto the darkerzones of the H. & D. scale are by transmitted light indistinguishable in printed films heretofore made, and may appear black or may show an imperfect or relatively lower light absorption in some other part of the spectrum, for example, blue, thus that the transmitted light in reo'neoe shifting the color quality of such light as is transmitted away from the red, giving purplish tones. Such a circumstance may arise, for example, in reproducing the image of a red curtain in which the folds actually 1 present all gradations of red from a brilliant carmine to an effective or possibly a true black. In the reproduced print or image of such a color range, as heretofore obtained the higher numbers or darker shades, as represented by proportionately greater densities of the dye substance, appear alike and substantially black.

Bv employing a dye which is characterized by fixation with the gelatine substance and by freedom from self-agglomerating components which deposit upon the surface, but which penetrates freely and preferably at a substantially uniform degree of dispersion or concentration throughout the depth or depths to which it reaches into the gelatine (thereby avoiding segregated layers of dye and also leaving the normal transparency of the gelatine unimpaired) improved color contrast effects are obtained by the present invention. It may be considered that by thus spacing the dye through an appreciable depth of the gelatine substance, substantially proportionate to the amount of dye imbibed in any unit of a-rea, the intensity of light may be transmitted through the gela-tine and dye undiminished and also be reflected from one minute dye surface to another, thus passingthrough intermediate paths of relatively transparent media. In this manner the transmitted light, which might be substantially excluded by a relatively thin but compact layer of dye,-as manifested more pan ticularly in the deeper shades and hence greater thicknesses and/or concentrationsmay be permitted to pass relatively freely, by transmission and reflection, through a film in which the same absolute amount of dye substance is applied per unit of area but is distributed'through an appreciable depth or thickness of the film wlth an intervening medium of transparent gelatine.

It is often found, however, exhibit a satisfactory degree of relative absorption towards matrices and proportionate netrabilities into the gelatine films to be printed therefrom (and hence make possible a wide range of contrasts, equal e. g. to the full H. & D. scale) tend also to present diffused or indistinct margins,-in short poor definition. This is thought to be attributable to the very factor of ready penetrability or absorption or imbibition into the gelatine film,-but possibly also to lateral dispersion of the dye.

By the present invention, this difiiculty is overcome by employing in the dye solution a viscosity agent capable of retarding dispersion of the solution, such as a second dye characterized by good definition and approthat dyes which 7 eer/see priate color value,,without regard to (or possiblyadvantageously of) low penetrability, Such addition is preferably made in relatively small. proportions,-and introduces the effect of arresting marginal creepthrough or upon the printed surface above alluded to, may be attributed to a slight retardation of the normal diffusion of the dye in the gelatine substance,which is more especially effective and more observable in the weaker or less active areas of dispersion. extraneous of the areas directly printed by imbibition contact. By way of comparison, such retardation in the normally liquid flow of the dye makes it resemble the flow of plastic substances, which is more restrictcd,and which ceases abruptly when the activating force is removed or falls below a definite value. I

Briefly defined, the method of the invention includes wetting a developed matrix film, typically presenting in its developed areas, a wide range of image contrasts (corresponding, e. g. to the full H. & D. scale) with a dye solution characterized. by mani festing selective and relatively proportioned adsorption toward such developed areas of the matrix on the one hand, and, on the other, a rapid and uniformly penetrative and distributive absorption into a relatively soft i. e. dye-absorptive) and preferably wet surface of a gelatine film (with or without qualifying agents as hereinafter set forth) and firmly contacting the thus wet matrix surface with the softgelatine surface to be printed, preferably underwater and for a short interval of time followed by separating the two surfaces,-and repeating the printing operation thereo'n, if desired, with other printing matrices carrying images, usually complemental to the first and with a dye or dyes of complementary colors.

More specifically, the invention is directed to reproductions upon surfaces of a gelatinous compositionsuch as those provided on transparent celluloid films and the like by coating with a gelatin solution. It is further desirable and, for purposes of highly satisfactory cinema production, practically.

essential that the coloring agent or dye shall be of marked though relatively uniform adsorption or penetration characteristics with respect tothe gelatinous surface, without appreciable tendency to difiuse laterally either through or over the gelatine surface, upon contacting therewith. A further desirable qualification of the dye is that it shall promptly become and thereafter remain permanently fixed in situ, as by a more or less stable chemical or physical association, with the gelatinous substance.

For example, the dye solution should not tend-to adhere to norbe withdrawn by the matrix surface, upon separation from the printed gelatine surface therefrom. And moreover it should attain its maximum depth of penetration relatively promptly, leaving a uniform distribution of dye therethrough, without subsequent tendency to disperse through the film, nor leave any superficial liquid to disperse laterally between the contacting surfaces.

The process of the invention will be described in its application for the preparation of multi-colored reproductions on films for moving pictures and the like. For such purposes a cellulosic film, of celluloid or other transparent material, is first prepared, such as is generally employed for photographic use. To this is applied a coating of a solution containing gelatine, a hardening agent such as potassium dichromate and usually an organic acid such as acetic acid. The coating thus formed is then allowed to dry rapidly and is subsequently hardened to the desired degree in known ways.

A plurality of matrix films, each bearing an image to correspond to one (or more) of the primary colors or to each of two (or more) complemental colors appearing in the reproductlon to be made, 1s next prepared, as by suitably exposing and developing or light printing and developing a photographic film therefor. For example, where the complementary colors red and green are to be provided, a film matrix may be prepared and developed to correspond to the red portion of the images in the subject to be reproduced and a second matrix film may be developed to correspond to the green portions thereof. This may be effected in any suitable manner, according to the appropriate photographic technique, which has been fully established for such purposes and is well known in the art.

For the purpose of making cinema reproductions, the matrix surface is most convenout the range of the H. & D. scale. The dye is not permanently absorbedby the matrix film, but may be transferred to a softer gelatine surface (as above defined) by contact. Hence, such matrices may be satisfactorily used for imbibition printing. However, it may be desirable that the dye-wet or printing areas shall also stand in relief above the nondyed portion of the matrix. To this end it is common practice to dissolve off the undeveloped areas of gelatine, which also removes gelatine from the partially developed areas substantially in proportion to their respective degrees or amounts of non-developed components. This leaves the image or images on the matrix surface,which are already developed, according to the corresponding initial light contrasts in the original, and hence with respect to the relative capacity of the surface to adsorb the dye solution, still further developed by physical relief.

In the application of the invention to the preparation of colored films these matrix images will be developed to represent the relative intensities of a single primary or complementary color component of the original or of the colored reproduction which is to be made. For this purpose, where multicolored reproductions are to be made, the following dyes have been found especially appropriate for producing complementary reds and greens:

Definition red .1 7 oiacn u acetic acid 5.0% -4 Made up to 18,000 cc. with water.

grams 900 cc.

Green Wool green S, sodium salt of tetramethyldi-amino-dl-phenyl B-hydroxy-naphthyl carhinol-disulfonic acid anhydride, color index 737 (4.5% egg-treated) 6,000 cc. Metanll yellow, sodium salt of M-sulfo-hcn- Y zcne-azo-di-phenyl amine, color index 138 22 grams Glacial acetic acld 600 cc.

Made up to 18,000 cc. with water.

The egg treament, mentioned above and V referred to in the formulae, consists in the ad:

dition of the white of egg or a like amphoteric colloid to the dye solution, followed by coagulation of the colloid as by boiling and removal of the coagulated colloid, together with extraneous solids or solid-forming constituents, from the solution.

The matrix film, bearing the images which are to be reproduced in red, is now immersed in the red dye solution, rinsed, and brought into firmand intimate contactwith the gelatinized surface of the blank film (preferably images and under water to eliminate gaseous enclosures of air) and a slight pressure is applied betweenthe contacting surfaces, as by passing between pressure rollers. Such contact is maintained'foran appreciable period of time, as determined by experiment to be sufficient for complete transfer ofthe dye from the matrix to the blank film. The films are then separated. The printed film is preferably dried, and next brought into contact 'with the matrix film bearing the images to bereproduced in green, which has been similarly wet by passing through the green dye solutiomand then rinsed. The two films are preferably brought together under water as before and pressed firmly together. Thereupon the green dye is transferred from the matrix to thegelatine surface and, by virtue of its complementary relationship thereto, forms a complete composite color reproduction on the gelatine film. The printed film is then dried in the usual manner and is ready for use.

In a printed film as thus produced it is found that the definition, i. e. accuracy of transfer in the narrow areas and margins of the several images and in the overlapped color areas, is greatly improved over procedures heretofore known and practiced in the art. It it also observed, upon passing light through the colored film and focusing the same upon a white surface, that the transmitted light is of purer color value than usually attained, manifestly a lower absorption of the color transmitted and a higher absorption in other portions of the spectrum, throughout the ranges of density and concening through subst ntially the entire H. & D. scale, metanil yel w and fast red S. conc. also reduce the apparent tendency of other dyes to creep and disperse beyond their margins into the film surface, so that a marked improvement in definition of the margins of overlapping of color zones is fected. c

It is to be understood that various moditration ordinarilyagncountered, and extendfications of procedure and substitutions of materials may be made within the scope of the invention but that such modifications and substitutions are to be considered as comprehended by the above disclosure and included within the terms of the following claims.

I claim:

1. A composition for imbibition printing, comprising a liquid characterized by containing a dye substance in solution and by normally manifesting a marked penetrability of the solid to be printed therewith, and a viscosity increasing agent, added thereto.

2. A fluid composition for imbibition printing, comprising a liquid characterized by containing a dye substance in solution and by normally manifesting a marked penetrability memos of the surface to be printed therewith and a second liquid characterized by manifesting low penetrability or dispersion into such surface, said liquids bein mut-uall miscible.

- 3. A fluid compositlon for im ibition printing comprising a dyesolution, characterized by normally manifesting a marked penetrability into a gelatinous surface, to depths proportional to the amount applied thereto and of uniform distribution throughout the penetrated depth, and a viscosity agent uniformly miscible therewith and characterized by imparting plastic flow to the composition.

4. A liquid composition for imbibition printin of films comprising a gelatine penetrative dye and a dye characterized by high /viscosity..

5. A dye soiution for use in imbibition printing, comprising a gelatine penetrative dye characterized by manifesting uniformity V, metanil yellow (color index 138).

me at Boston, Massachusetts,

Signed by this 25th day of May, 1927. i

,. BERTHA SUGDEN TUTTLE.