US3080230A - Photographic stratum transfer process and element therefor - Google Patents

Description

March 5, 1963 H. HAYDN ETAL 3,080,230

PHOTOGRAPHIC STRATUM TRANSFER PROCESS AND ELEMENT THEREFOR Filed Jan. 29, 1957 SILZz/erhaZL'de negative emulsion Uuzl includes developer and can corzlaz'n mozlsture-evolvug irgredzenb.

Expose io imogg'e Press ceyccinsitransfer Zoger at 80:1500. i0 cffeci developmeni and of exposed aweors ofemulszlow. If emulszlorz/ does not coniacirz, or moisture -evo Zwbg ingradient hen ihe Zrocnsfer Za yer" does.

Separccle irarzsfer Za yerfivm emulsion layer so as to cause Mimi/716d emulsion, arrears Z0 be carried by transfer" Layer:

Non: lcderalgreversed pas iiive is ikerebyprovided wz'ihoul the useof bodzes ofprooessing INVENTORS lzfildegard Haydn An z'lat Uon/ JCo'u iy F ATTORNEYS v. t L fi PHGTO GRAPHHC STRATUM TRANSFER PRGCESS H AND ELEMENT THEREFOR Hildegard Haydn, Anita von Kiinig, and Edith Weyde', Legregkusen, Germany, assignors to Agra Alitiengese'llso a t Filed .Fan, 29, 1-957, Sen.- No; 636,863 Claims priority, application Gerrnany Feb. 18, 1956 Claims. (Cl.-96--27) The present inventionrelates to a process for the direct production of positives by means of silver halide emulsions which are developed by heat without applicatiorr of any processing baths. p I

For the production of non-laterally reversed positive copies, it is already known to expose a silver bromide halide emulsion layer containing silver halide developing substances to the object to bereproduced and to heat said exposed material to temperatures of about 80450 C. after it is brought into contact with a transfer layer. With this procedure, the developing substance, which is contained in the photographic silver halide emulsion layer and which has remained unused at the unexposed areas, is" transferred to the transfer layer which is disposed in contact with the emulsion layer and which contains one or more substances which yield colored compounds with the said developing substance. Oxidizing agents and aromatic diazo and nitro'so compounds are proposed by way of example as reactants in the positive layer.

It has now been found that direct positives are obtained in a simple manner if the silver halide developing substances which are usedare those which so change the binding agent of the silver halide layer with the reduction of the exposed silver halide that itbecomes" infusible and unswellable, while the unmodified silver halide emuls'ion at the unexposed areas is used for building up the positive image by transferring the said unmodified silver halide emulsion to the transfer layer and reducing it in the transfer layer to a silver image. Such silver halide developing substances are referred to herein as tanning developers.

Suitable silver halide developing substances of this type are polyhydroxy compounds of benzene, napthalene and diphenyl, which can be substituted in the nucleus by halogen atoms or alkyl', aralkyl, aryl or cycl-oalkyl groups, for example, pyroca'techol, hydroquinone, 2,3- dihyd roxy naphthalene, 2,6-dihyd roxy naphthalene, 3,4- dihydroxy diphenyl, 2,3-dihydroxy diphenyl, 1,2-dihyd roxy-'4-cyclohex-yl benzene, 4'-benzyl' p'yrocatechol and 4-cloro=pyrocatechol. With the application of heat, these developing substances not only reduce the exposed silver halide, but they also modify the gelatin, probably due to the formation of oxidationproducts, so' that itbecomes infusible and unswellable, while it remains unchanged at the unexposed places. This unmodified gelatin of the layer can now be brought during heat develop m'ent or at a later stage into' contact with a second layer which has" the ability to" adhere firmly to the unmodified gelatin so that, when the two layers are separated, portions of the gelatin are stripped from the negative layer. In this way, the non=laterally reversed positive of the copied original is obtained .on the second layer, which is the so-called transfer layer, this positive being in the form of a gelatirr relief which still' contains silver halide and developing substance. If this gelatin relief on the transfer layer is now exposed todiffused light and again subjected to heat treatment, the record becomes deep black in color. A- black coloring or the record eaii also be obtained by using an emulsion of appropriate composition or by adding suitable compounds to the positive layer.

it is" a particillar advantage or the" present process that" both the development process and the transfer process are effected only by heat and without any additional wet treatment.

The accompanying drawing is a now sheet of the processes described herein.

Any silver halide emulsion can be used for the production of the negative layer, such as silver chloride, silver bromide, silver chlorobromide, and silver iodobrom'i'de emulsions. As binding agent, it is possible to use those which are normally used in the photographic art and which are hardened by the action of heat by developer-oxidation products, such as for example, gelatin, polyvinyl alcohol, carboxymethyl cellulose and mixtures of these substances. The pH value of the emulsion is preferably adjusted to about 3.5-6.5. In order to accelerate' the initiation of the developing process, it is advisable to add non-tanning silver halide developing substances, such as p-methyla'rnino phenol, p-amino phenol or their substitution products, to the hardening developers in amounts up to about 20% by weight as calcul'ated' on the tanning developer.

For stabilizing the developing substances, it is possible to add to the photographic layers substances which slowly split off sulphur dioxide or sulphurous acid and the cleavage products of which do not cause either a hardening of the gelatin or any other undesirable influencing of the silver halide emulsion during storage. Examples of such substances are bisu-lphite compounds of such aldehydes or ketones as do not harden gelatin. Particularly suitable for this purpose are aldehydes and ketones which have a relatively high boiling point, particularly a boiling point higher than C. Such aldehydes are aromatic, ar'alipha'tic aldehydes, and heterocyclic aldehydes, such as be'nzald'ehyde, terephthalaldehyde, cinn'amaldehyde, salieylaldehyde, furfural, Whereas cycloaliphatic ketones, such as cyclope'ntanone and cyclohexanone, and ar'aliphat'ic ketones, such as benzala'eetone, and heterocyclic ketone's', such as isatin, are the most suitable ketones. The acetonebisulphite compound would be less suitable, since this substance only gives slight protection against oxidation of the developer because it has a comparatively strong tendency to decompose with volatilization of the acetone. Examples of substances which are particularly suitable are: Terephthalaldehyde bisulphite, cinnam'aldehyde bis'ulph'ite, benzal'dehyde bisulph'it'e, salicylal'dehyde bisulphite, cyclohexa'none" bisulphite, cycl'opentanone bisulphite', and f-urfural bi'sulphite, these compounds being preferably used in the form of their alkali-metal salts, suefr as their sodium, potassium, and lithium salts. The organic developing substances are preferably applied in quantities of about 0.5-3 g. per cc. of an ordinary silver halide emulsion, whereas the aforementioned stabil'izers are preferably used in quantities of- O.2-'2 parts per part by weight of organic developing substance.

In addition, it is important that compounds splitting off water should be added to the emulsion ofthe negative material or the transfer layer. Suitable additive compounds of this type are salts of inorganie or organic acids containing water of crystalliiatiorr, such as for example, sodium citrate (C H G Na 51-33 0) sodium acetate (CH COONa-3H O), e'alciuin aeeta'te (ICa-(CH C0O') 2 2H O) trisodium phosphate Na3P0 4-1'2H 0'), sodium sulphate mason, arid/or substances which ensure a high residual moisture content, such as, for example, glycol, glycerol, and sorbit-o'l. These substances are preferably used in such amounts that thjiwat'er content of the negative material amounts to 8-42, preferably 8-10 percent by weight. When these additives are used in the transfer layer, the moisture necessary in the development- -or at a later stage.

assesses migrate during the processing from the transfer layer to the negative layer.

The negative layer can be arranged on any suitable layer support which is stable at the temperatures usually used for heat development, such as for example, paper,

plastics, textile fabrics and metals. Between the support and the emulsion, it is advantageous to use an intermediate layer by which the holding strength of the emulsion layer is reduced so that the stripping of the unexposed gelatin is promoted. Particularly suitable for this intermediate layer are alcohol-soluble heat-resistant substances, such as ethyl cellulose, polyvinyl pyrrolidone, zein, polyethyl acrylate and polyvinyl acetate. Any suitable heat-resistant support can be used as transfer layer. The transfer layer can be any suitably coated or uncoated paper, or a plastic, fabric, or metal foil. With coated transfer papers the coating of the said paper can contain additives which split off water and also additives by which the transferred record is blackened, such as, for example, nitrogen-containing organic compounds as, for instance, N-diethyl aminoethanol, triethanolamine, tetrarnethyl am- -monium hydroxide, pyridine, piperazine, hydrazine, or compounds containing sulphur, such as thioacetarnide. -These additives may be used in quantities of about 1-10 g. per g. of binding agent, although other proportions are useful.

The production of the positive or the transfer process can either take place together with the developing process Furthermore, several copies can be made from the negative, this taking place immediately after the first transfer or at different later stages. However, care should be taken that the negative is not exposed to light in the intervening period.

EXAMPLE 1 Negative Zayer. g. of pyrocatechol, dissolved in a small amount of water, 10 g. of terephthalaldehyde bisulphite, 200 g. of sodium acetate containing water of crystallization (CH COONa-3H O) and 0.05 g. of benzotriazole are added to 1 liter of any desired silver halide emulsion. Other additives known in the emulsion art can also be used. The emulsion is cast on paper or another layer support and dried.

Transfer layer.A 1% solution of acetyl cellulose acetobutyrate in acetone is cast on a layer support, such as, for example, paper, and then dried. It is advisable to add a plasticizer such as a phthalic acid ester, to the layer.

Processing.After exposure to an image, the negative is brought into contact with the transfer layer. The negative and transfer layer are then subjected to a temperature of 90 to 150 C., preferably l10l20 C., for 5 to seconds in a hot press. The transfer layer can be heated at a lower temperature. After separation, the gelatin of the unexposed areas adheres to the transfer layer. After subsequent exposure thereof with diffused light and after reheating, a deep black unreversed positive is obtained of the original image.

EXAMPLE 2 Negative layer.-20 g. of pyrocatechol and 2 g. of prnethylaminophenol sulfate in a small quantity of Water, are added to 1 liter of any desired silver halide emulsion. This emulsion has added thereto 6 g. of cyclohexanone bisulphite, 180 g. of sodium acetate containing Water of crystallization, and 0.05 g. of benztriazole or corresponding amounts of other stabilizers. This emulsion is cast on a support as in Example 1 and dried.

Transfer layer.A 1% alcoholic solution of acetyl cellulose has 5 g. of piperazine per liter added thereto. The solution is cast on a support and dried.

Processing-T he processing takes place as in Example 1, but the after-treatment of the positive is superfluous since blackening of the transferred layer is effected by the piperaziue.

4 EXAMPLE 3 Negative layer.25 g. of 4-cyclohexyl pyrocatechol, dissolved in 30 cc. of dimethyl formamide, are added to one liter of any desired silver halide emulsion. 10 g. of terephthalaldehyde bisulphite, 225 g. of sodium acetate containing Water of crystallization, 0.05 g. of benztrilazole, and 0.03 g. of phenyl mercaptotetrazole are then added to the emulsion, which is then cast on a support as in Example 1 and dried.

Transfer layer.A 2% solution of a copolymer of 30% acrylic acid and 70% of methyl methacrylate in dimethyl formamide is cast on a layer support and dried.

.Pr0cessing.--As in Example 1.

EXAMPLE 4 Negative layer.22 g. of monotertiary butyl pyrocatechol are introduced into 1 liter of silver chloride emulsion and then to the emulsion is added 200 g. of sodium acetate containing water of crystallization and 5.5 g. of cyclopentanone bisulphite. Stabilizers and other known additives such as wetting agents can be added.

Transfer layer.A 3% solution of polyacrylonitrile in dimethyl formamide is cast on a layer support and dried.

Pr0cessing.-As in Example 1.

EXAMPLE 5 Negative layer.-20 g. of pyrocatechol, dissolved in a small quantity of water.

I l g. of pmethylaminophenolsulphate 8 g. of salicylaldehyde bisulphite 0.08 g. of benztriazole 0.02 g. of phenyl mercapto tetrazolc and 15 cc. of glycerol are added to each liter of a silver halide emulsion.

This emulsion is cast on a support :as in Example 1 and dried.

Transfer Iayer.3 cc. of N-diethyl aminoethanol are added to liter of a 3% alcoholic solution of a condensation product obtained from hexamethylene diamine adipate and caprolactam(epsilon-caprolactam).

Pr0cessing.-As in Example 2.

EXAMPLE 6 Negative [cyan-The starting material is a silver halide emulsion in which 10 to 30% of the normal gelatin is replaced by one of lower constants, i.e. and a gelatin which has been partially degraded as, for instance, by heating an aqueous solution of gelatin at a temperature of 80 C. for several hours. Developer and additives can be those of Examples 2-5.

Transfer layer.A fine mesh fabric such as silk gauze or plastic fabric is suitable as positive material. The fabric can also be coated with one of the aforementioned plastic solutions.

Processing.As in Example 1.

EXAMPLE 7 Negative layer.The starting material is a silver halide i emulsion in which 15% of the gelatin is replaced by polyvinyl alcohol. The additives can be the same as in the preceding examples.

Transfer layer.-One of the layers described above is used as positive layer, and the processing then takes place accordingly.

EXAMPLE 8 scribed is used as positive and also an ordinary piece of Writing paper.

Processing-As in Example 1.

EXAMPLE 9 A silver chloride emulsion with the following additives per liter of emulsion is used for producing the negative layer:

20 g. of pyrocatechol, dissolved in a small amount of water,

10 g. of terephthalaldehyde bisulphite,

0.1 g. of nitrobenzimidazole, and also 0.05 g. of mercaptobenzthiazole.

Transfer layer.The paper is impregnated with a 10% sodium acetate solution and is then used as the transfer paper. On being heated, this paper gives oif a certain amount of water which accelerates the reactions.

PrcessingAS in Example 1.

EXAMPLE 10 Negative layer.--

20 g. of 2,3-dihydroxy naphthalene,

g. of te-rephthalaldehyde bisulphite,

0.05 g. of henztriazole,

0.02 g. of mercaptobenzthiazole,

g. of sodium acetate trihydrate (CH COONa-3H O),

and

5 g. of sorbitol are added to each liter of a silver chlorobromide or silver chloride emulsion.

This solution is cast onto a paper which has been treated beforehand with a 1% alcoholic solution of ethyl cellulose.

Transfer layer.Any desired writing paper can be used.

Processing.-After exposure, the negative is brought into contact with the transfer layer. The negative and transfer layer are then passed between two heated rollers, in which they are subjected to a temperature of approximately 90 to 150 C. The two layers are then quickly pulled apart, only some of the unexposed negative layer remaining adhering to the positive (transfer) paper. The operation can be repeated 3 or 4 times in the same way. The thickness of the negative layer is of importance, since it is possible to produce more copies with a thicker coating of negative layer.

We claim:

1. A photographic material for preparing positive photographic images without the use of bodies of processing liquid, said material including a support and a light-sensitive tannable silver halide emulsion layer on the support, the emulsion layer containing an effective amount of a tanning delevoper, a non-tanning developer in an amount effective to accelerate the initiation of the development, and for every part by weight of developer about 0.2 to 2 parts by weight of a bisulphite of a compound selected from the group consisting of aldehydes and ketones that have a boiling point above 80 C. and that do not harden the emulsion.

2. A photographic material for preparing positive photographic images without the use of bodies of processing liquid, the said material including a support and a lightsensitive tannable silver halide emulsion layer on the support, the emulsion layer containing an effective amount of a tanning developer, a compound that evolves moisture at a temperature between 80 and 150 C. and in a concentration such that the water content of the emulsion is from 8 to 12%, and a bisulphite of a compound selected from the group consisting of aldehydes and ketones that have a boiling point above 80 C., the bisulphite being present in a concentration between 0.2 and 2 parts by weight for each part by weight of the developer.

3. A process for the product-ion of non-laterally-reversed positive photographic images without the use of bodies of processing liquid, which process comprises exposing to an original image a light-sensitive silver halide emulsion layer containing a tanning developer that causes the emulsion to be tanned in its photographically exposed areas when developing action takes place, and also containing, in an amount between 0.2 and 2 parts by weight per part by weight of the developer, a bisulphite of a compound of the group consisting of aldehydes and ketones that have a boiling point above C. and that do not harden the emulsion layer, pressing the exposed emulsion layer against a transfer layer at a temperature between about 80 and C., at least one of these two layers containing a moisture-evolving compound that provides sufficient water for the hot pressing to effect development and to cause undeveloped portions of the emulsion layer to adhere to the transfer layer, and thereafter separating the transfer layer from the emulsion layer so that the transfer layer removes the adherent portions of the emulsion layer and provides the desired photographic image.

4. A process as defined in claim 3 in which the moisture-evolving compound contains water of crystallization.

5. A process defined in claim 3 in which the moistureevolving compound is hydrated sodium acetate.

6. A process defined in clam 3 in which the moisture is supplied by incorporating in one of the layers a moistening compound selected from the class consisting of glycol, glycerol and sorbitol.

7. The process of claim 3 in which the transferred portions of the emulsion are made darker in appearance.

8. The process of claim 3 in which the emulsion contains a non-tanning developer in addition to the tanning developer, and the transfer operation is conducted under conditions that cause the non-tanning developer to darken the transferred portions of the emulsion.

9. A process as defined in claim 3 in which the transfer layer contains a blackening agent that causes the blackening of the transferred portions of the emulsion.

1-0. A process defined in claim 9 in which the blackening agent is selected from the class consisting of N-diethylaminoethanol, triethanolamine, tetramethylammonium hydroxide, pyridine, piperazine, hydrazine, and thioacetamide.

References Cited in the file of this patent UNITED STATES PATENTS 742,405 Eichengriin Oct. 27, 1903 1,954,325 Martinez Apr. 10, 1934 2,596,756 Yutzy et al. May 13, 1952 2,675,313 Yutzy et al. Apr. 13, 1954 2,716,059 Yutzy et al. Aug. 23, 1955 2,747,999 Yutzy et al. May 29, 1956 2,835,575 Cowden et al. May 20, 1958 2,865,745 Chan et al. Dec. 23, 1958 FOREIGN PATENTS 2,971,840 Germany Feb. 14, 1961 392,938 Great Britain May 26, 1933 399,269 Great Britain Oct. 5, 1933 427,962 Great Britain Apr. 29, 1935 OTHER REFERENCES 70 Henry Holt, 1947, p. 152..

UNITED STATES PATENT OFFICE QERTIFICATE ()F CORRECTION Patent N00 3 080 230 March 5 1963 Hildegard Haydn et ale It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1 line 43 for "napthalene" read naphthalene line 5O for "4010r0-pyrocatechol read d chloro pyrocate ch01 column 2 line 64L for (Na3POd-12H O)" read um (Na PO 12H O) line 65 for "(Na SO read W (Na SO -1OH O) a Signed and sealed this 1st day of October 1963,

(SEAL) Attest:

I Attesting Ufficer ERNEST We SWIDER. DAVID L LADD Commissioner of Patents 4

Claims (1)

1. 3. A PROCESS FOR THE PRODUCTION OF NON-LATERALLY-REVERSED POSITIVE PHOTOGRAPHIC IMAGES WITHOUT THE USE OF BODIES OF PROCESSING LIQUID, WHICH PROCESS COMPRISES EXPOSING TO AN ORIGINAL IMAGE A LIGHT-SENSITIVE SILVER HALIDE EMULSION LAYER CONTAINING A TANNING DEVELOPER THAT CAUSES THE EMULSION TO BE TANNED IN ITS PHOTOGRAPHICALLY EXPOSED AREAS WHEN DEVELOPING ACTION TAKES PLACE, AND ALSO CONTAINING, IN AN AMOUNT BETWEEN 0.2 AND 2 PARTS BY WEIGHT PER PART BY WEIGHT OF THE DEVELOPER, A BISULPHITE OF A COMPOUND OF THE GROUP CONSISTING OF ALDEHYDES AND KETONES THAT HAVE A BOILING POINT ABOVE 80* C. AND THAT DO NOT HARDEN THE EMULSION LAYER, PRESSING THE EXPOSED EMUL-

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