US2537924A

US2537924A - Photographic-imbibition dye printing process

Info

Publication number: US2537924A
Application number: US777494A
Authority: US
Inventors: Walter J Weyerts
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1947-10-02
Filing date: 1947-10-02
Publication date: 1951-01-09
Anticipated expiration: 1968-01-09
Also published as: GB664836A

Description

Jan, 9, 1951 w, J, wE -rs 2,537,924

PHOTOGRAPHIC IMBIBITION DYE PRINTING PROCESS Filed Oct. 2, 1947 H COLLOID MATRIX C'ONTA/NMG' DYE AND ARYL JULFON/C ACID WALTER J. WEIERTS IN VEN TOR 1th PM UZML/M ATTORNEYS Patented Jan. 9, 1951 PHOTOGRAPHIC-IMBIBITION DYE i PRINTING PROCESS Walter J. Weyerts, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application October 2, 1947, Serial No. 777,494

9 Claims. 1

This invention relates to color photography and more particularly to a process in color photography of controlling the contrast of dye images in the imbibition dye printing process.

In the imbibition dye transfer process of color photography the method of controlling contrast of dye images by adjustments in pH of the dye baths with, for example, ordinary acids such as acetic acid, is well known. With solutions of acid dyes at relatively high pH values or the order of 4-5, low-contrast images are obtained with transfers from gelatin relief matrices. As the pH of the dye baths is lowered the contrast of the transfers becomes higher until a certain pH is reached below which the matrices will not take up any noticeably increased amounts of dye. Therefore a maximum contrast is reached. A given increment in pH will cause increasingly greater changes in contrast as the pH of a dye bath is raised above the value of maximum contrast. Dye solutions above pH of about 4.0 are very sensitive to slight changes in pH, some dyes showing a noticeable effect on contrast with a change of only 0.1 pH unit. A similar change in pH of a dye bath at pH values below about 3.0 with most dyes has a negligible efiect on the contrast of a print. Furthermore dye baths at these lower pH values show less effect of dye concentration on the density of the prints. Because of the above effects it would be advantageous to work with dye baths at low pH ranges if some means could be provided for varying contrast at the low pH values.

According to my invention contrast is controlled in imbibition dye printing processes, particularly at low pH ranges, by incorporating into the dye baths certain organic acids or their soluble salts which compete with the dye when incorporated into a matrixior transfer to the imbibition dye printing blank. One advantage of my process lies in the fact that I am able to work at low pH ranges where slight changes in pH have but little eil'ecton contrast. I am also able to obtain low contrast dye images when operating at low pH values. Further, operating according to my invention the concentration of dye in a dye bath is not as critical as previously since dye concentration has less effect in ranges of low pH. Also some dye baths are more stable when operating within the low pH range.

One object of my invention isto provide a new type of dye bath suitable for varying contrast or controlling contrast especially at low ranges of pH. Another object of my invention is to provide a; dye bath suitable for use at practically any (c1. nil-149.1)

is to provide the materials and describe the process of using the same in a dye imbibition print ing process. Further objects of my invention will become apparent by consideration of the following description of my invention.

These objects. are accomplished by incorporating into a dye bath suitable for use in the imbibition dye printing process a substantially colorless aryl sulfonic acid and treating an imbibition dye printing matrix with this bath and printing dye images from a matrix'thus treated in the usual manner.

My invention may be readily understood by consideration of the following drawings wherein Fig. 1 shows an enlarged cross-sectional view of a photographic film carrying a matrix containing dye and an aryl sulfonic acid of the invention. The photographic element, according to Fig. 1 of the drawings, consists of a support Ill generally composed of a. cellulose ester film base or other suitable material such as paper or a synthetic resin film-forming material. Support In carries the matrix relief images I I containing dye and the aryl sulfonic acid or acids of the invention dispersed in a colloid such as, preferably, gelatin,

albumin or a synthetic resin; for example, polyvinyl alcohol. Generally, my invention operates better using gelatin as the colloid material because of its well-known response to variations in pH in the imbibition dye printing process.

My invention will now be described with particular reference to the accompanying drawings. I take a substantially unhardened emulsion layer coated on a support such as ll! of Fig. 1 of the drawings, and process it to a relief image by the methods well known to the art and following this treat the relief image with an acid dye bath the pH of which may be controlled by the use of acetic, citric or similar acids, the bath also containing a water-soluble high molecular weight aryl sulfonic acid of the invention, or a soluble salt thereof, such as an alkali metal salt. and then the dyed matrix is used for printing dye images in the conventional manner by superimposing the matrix onto an imbibition blank such as paper carrying it desirable a colloid layer such as gelatin containing a mordant. The organic acids of the invention which are used in the dye bath in addition to the acid such as acetic acid are, phenolphthaleine-, terephenyl-, aryl methane, napht alene-. naphthol-, naptholamine-. naphthylamine-, diphenyl-. hydroxy-diphenyl-, anthraquinone-sulfonic acids, and certain benzene sulfonic acids having a straight chain of carbon 3 atoms or halogen atoms substituted on the benzene ring, and the water-soluble metal salts such as the alkali metal salts of these acids.

As examples of the acids which are suitable for use in the dye bath according to my invention are the following list of compounds which are by no means exhaustive of those acids or salts which are suitable. The acids are numbered for convenience of later reference thereto.

fonate Sodium diphenyl methane p,p-disulfonate Sodium-o-terephenyl-4-sulfonate Sodium-m-terephenyl-4 =-sulfonate The acids orsalt form of the above is used depending on which is most convenient or from solubility which is most desirable.

Not all aryl sulfonic acids function in the optimum' manner when incorporated into the dye bath. Some other acids, or salts of such acids, would not ordinarily be used because of their insolubility or limited solubility in the dye bath when Water is used as the solvent for dispersing the dye used for making the transfer to the imbibition blank. When solvents are used in the dye bath for dispersing the dye and acid, the group of'compounds suitable is enlarged. Benzene sulfonic acid or toluene sulfonic acid are generally not very effective in varying or controlling the contrast at the low pH range. Similarly, when the carbon chain on the aromatic nucleus is of such length that the acid assumes the character of wetting agents, the acid is generally not suitable for use in my invention. With benzene sulfonic acids, generally the limit to the number of carbon atoms in the chain is four. Similarly, when the nucleus consists of a naphthalene group the alkyl substituent should not be so long (more than 4 carbon atoms) that the compound has the character of a surface-active compound. The surface-active compounds are useful in reducing highlight densities and in cutting back the toe of the characteristic curve. In the preferred embodiment of my invention I use aromatic sulfonic acids having a naphthalene, anthraquinone, triphenyl methane or diphenyl nucleus. The acids suitable for use in my invention are compounds having chemical structures and imbibition properties similar to imbibition dyes, and when present in the dye solutions act in competition with the dyes for transfer to the imbibition blank. The acids should be substantially colorless so as not to change the color-balance of the print, except insofar as this may be desirable. By varying the amount of the sulfonic acid in the dye solution or the particular dye, or the manner in which Mono-butyl phenyl phenol sodium monosul- 4 the matrix is treated with the sulfonic acid or the dye, and the pH of the dye bath, a wide range of control of contrast may be attained.

In the following table, the examples of dyes and dye baths are given as representative of the materials anddye baths suitable for use in my invention. In the table the eflect on contrast of variation in amount of aryl sulfonic acid given.

Table A l Sul- Aryl Sulfonic Matrix Dye pH fOIllC Acid Contrast I Acid No. Colleen. No.

Per cent 0. 0 1. 4 1 0.1 l. 2 1 0.5 .7 l 0 1. 4 2 6 1. 2 2 1. 5 0. 6 2 0. 5 0. 6 2 0 1. 6 3 1. 0 1. 0 3 0 1. 2 4 25 0. 6 4 5O 0. 2 4 0 1. 2 5 1 l. l 5 .4 0.6 5 0 0. 5 5 1 0. 4 5 4 0. 2 5 0 1. 2 6 1 0. 9 5 .4 0.5 5 0 0. 6 5 1 0. 4 5 l 0. 3 5 0. 2 i. 2 a

1 Dye A=Brllliant Alizarin Light Red B (a sulfonated benzanthrone) (concn. 0.075%

Dye B=Erio Fast Cyanine S (a sulfonated anthraquinone) (concn. 0.075%).

The characteristic curves from which the above dataare obtained were made by'transfer of step tablet exposures from matrices Nos. 1-6 treated with the dye baths of composition indicated onto mordanted and hardened gelatin-coated paper, the curves being platted as functions of log E and optical density by reflections through a complementary colored filter.

As will be apparent to those skilled in the art, in comparing H and D curves a true picture is obtained only from comparison values of both contrast and density at definite log E values. For that reason the above contrast data only give indications of relative densities at log E values in the straightline portion of the curves whereas the actual curves from which the data was taken showed, especially with the rinsed matrix No. 6, appreciably less density at a given log E value when the sulfonic acids were used instead of acetic acid in the rinse bath.

The concentration of the sulfonic acid used in the dye bath varies somewhat depending on the type of dye used and the type of sulfonic acid used; that is, the effectiveness of the latter in controlling contrast, but .generally the concentration of the sulfonic acid is of the order of 0.1% to 2.0% or more.

An added effect of some of the sulfonic acids of my invention, such as benzene sulfonic acids, consist in a contrast control eifect which is manifest by the cleaning out of the highlights in a dye print. This effect is contemplated by my invention but is not generally'the effect desired from the majority of compounds falling within the scope of my invention. The efi'ect ordinarily obtained is that of lowering the contrast or varying the contrast by raising or lowering the shoulder of the characteristiccurve of the imbibition dye print. I generally prefer to incorporate the sulfonic acid into the dye bath; however, I may, in a variation of my invention, before or after dyeing the matrix, treat it with a solution of the sulfonic acid. The table shows the compositions of suitable baths for this purpose.

1 My invention having thus been described, it is to be understood that the disclosure herein is by way of example and I include in the invention all modifications and equivalents falling within the scope of the appended claims.

What I claim is:

1. The process of controlling the contrast of dye images in an imbibition dye printing process, which comprises incorporating into an acid imbibition dye bath containing an acid dye a watersoluble organic compound of the group consisting of substantially colorless aryl sulfonic acids having an alkyl substituent of 0 to 4 carbon atoms and water-soluble alkali metal salts of said acids, treating an imbibition dye printing matrix with said dye bath and transferring by imbibition a dye image from said dyed matrix to an imbibition dye printing blank.

2. The process according to claim 1 wherein the organic compound is of the group consisting of water-soluble naphthalene sulfonic acids and water-soluble alkali metal salts thereof.

3. The process according to claim 1 wherein the organic compound is of the group consisting of naphthol sulfonic acids and water-soluble alkali metal salts thereof.

4. The process according to claim 1 wherein the organic compound is of the group consisting of diphenyl sulfonic acids and water-soluble alkali metal salts thereof.

5. The process according to claim 1 wherein the organic compound is of the group consisting of terephenyl sulfonic acids and alkali metal salts thereof.

6. The process according to claim 1 wherein the organic compound is 4-su1fo m-terephenyl.

7. The process according to claim 1 wherein the organic compound is of the group consisting of anthraquinone sulfonic acid and alkali metal salts thereof.

8. The process according to claim 1 wherein the organic compound is anthraquinone-beta sulfonic acid.

9. The process of claim 1 wherein the organic compound is of the group consisting of 2-naphthol-8-su1fonic acid and water-soluble alkali metal salts thereof.

WALTER J. WEYERTS.

REFERENCES CITED The following references are of record in the Number Name Date 1,484,346 Ullmann Feb. 19, 1924 1,517,200 Donisthorpe Nov. 25, 1924 1,926,556 Nusslein Sept. 12, 1933 35 2,131,146 Schlack Sept. 2'7, 1938

Claims

1. THE PROCESS OF CONTROLLING THE CONTRAST OF DYE IMAGES IN AN IMBIBITION DYE PRINTING PROCESS, WHICH COMPRISES INCORPORATING INTO AN ACID IMBIBITION DYE BATH CONTAINING AN ACID DYE A WATERSOLUBLE ORGANIC COMPOUND OF THE GROUP CONSISTING OF SUBSTANTIALLY COLORLESS ARYL SULFONIC ACIDS HAVING AN ALKYL SUBSTITUENT OF 0 TO 4 CARBON ATOMS