US2209087A - Production of photographic diazotype prints - Google Patents

Description

{Patented July 23, 1940 PRODUCTION on sr'no'roouarnre Q nmz o rm'rnmrs,

Werner, Paul Leiicli, London, England, assignor a to Eugene Dietzgen Company, New 10th,

No Drawing. Application October 25, 1934, 8

invention relates to the production. of

photographic diazotype prints and has ior ob- Ject to provide improvements therein. In the productionof diamtype prints, three (compounds aregenerally used, namely: 1 (1) A diazo-salt which bleaches out when ex posedto light under a drawing.

. l (2) A coupling component capable of form- M ingan az'o-dyestufl with the undecomposed diazobody.

commercialscale, namely:

f containingbotnthe diazo-body and the coupling component. In casepto bring about the development for the picture,after the ,paper has to the light under a drawingonly thethird component namely, alkali, has ,tofbe s I is generally done byexposing, the y print to theaction of ammonia fumes.

Kb) The paper is prepared with a solution-con taining the diazo -body only (generally in. pres- {ence of an acid or acid salts) For the develop-; ment of this paper, ali'quid developer contain- I ing in addition toiithelalkali, alsothecoupling component, has to be applied: in athin layer. Method ,(a) is generally described. as (the dry development, process, and method (bJf-asrthe Ji d I, 0 ya" semi-dry development process. Both-processes are on alargescale. 5

1 In papers prepared according,to fniethod fidi [only couple under alkalineconditionsff or else some 'p'rccess such as; acute dehydrationmust be employed to prevent the'coupling process taking a place before development: and even ii. somesuch the diam bodieschos'en must either be such that process is employed theldiazlo bodies chosen must be bodies which react onlyl slowly in neutral or acid conditions. lphowever, have found that if ,thecoupling component ,isintroduced into the "containing the diazo body, by dusting the coupling component inpowder form over the film when dry,-II can use anydiazo body which is :not either a diazo-anhydride or which has notbasic substitutions which are not neutralized by suitable negative substitutions (for instance, aminoacylamino a, compounds can be used and derivatives of the diphenylseries are particularlyusuitable, as well as those of the 'di-and triphenyl- Alkali, orf'a substance having an alkaline reaction which permitsthecoupling to takeplace.

1 'I'hereare two methods by which thediazov H -typeiprocessghasbeencarried outso i'ar on a (a) paper is prepared withja solution a o pe paper o te f a e itive e layer containing a diazo'compound that is ca- [-pabl'e oi'coupling in neutral or acid conditions;

phenolic coupling component in the light-sensi-I 1 Plinghas taken place priorto the actual de;

velopment. 1 l l The object of the' presentinvention is to provide a paper which can be developedin a simpler and morefadvantageous manner, namely,

one which shows thejjiollowing ,fe'atures I The used! either the gaseous method'oi V developme'ntior the seini-drymethod for the same" paper.

- zxrne ama the use of hairpin;

kaline reacting substances 'i'or development; 1

1 3. The carrying out of. the gaseous method of development by"means simply oiwater Yvapour,

thus avoiding the use of ammonia "iumes. According to the present invention! prepare a u and which would not permit the inclusion ofthe' ,tive layer owing. to premature couplingitaking. 1

place. After sensitizing, anddrying, the paper is" then treated with a coupling componentjbysub-- j sequently dusting fit over with a fine powdercone I 1 taining either the coupling component alonefor i in admixture. with other substances, thevuse which isfmore fully, described later. The paper, when readyfor. use, contains therefore the light-.- sensitive diazo substance in the coating, andal-j' 1,- so carries the coupling component capable of forming a dyestufl with the undecomposed diazo Aiter exposure tolight in the way, the print mayjbev developed simply by the action 0Q water. Itijis 'particularlyadvantageous to use waterioifjdevelopment in sucha way as not appreciably to' wet the paper so that development maybeicarried'out by the dry process as previously deflnedz' Thisfmay advantageously done by exposing the paper tosteam or other form oi water vapour. In order to develop the,

- print in reasonableume, it is of courseadvantageous to water vapour in a concentrated iorm, namely, in the-form of steam or water, vapour arising; from heated water.

"In addition to water vepour other methods can be used for developing the print, and in particular other methods which do not appreciably wet the paper. For example, insteadoi water vapour the paperlmayl he treated with a quick y moist acetone. I V

"Another method 01, dry development-by means drying liquid, such asmoist methylated spirit, or Y oi water is tousera gelatine composition. Aflat tray, plate or other support, of suitable dimenu I v kil ;containing a jelly formed ofjg'elatine'and,

water .is used and-the print, after exposure, is

pressed facedownwards; on to the jelly, The moisture in' the Jelly is sufficient to ,bring rabout development in a few seconds; leaving adryprint'.

A Jelly of suitable composition is one containing 60 gramspf gelatlne and 20-30 cc. of glycerine in 500 cc. of water.

Development may also conveniently be carried ;out by utilizing the loosely combined moisture in ;a suitable hydrated salt,such as hydrated sodium sulphate. For example, hydrated sodium sulphate may be incorporated in the paper before coating, or it may be incorporated in the lightachieved of obtaining a print which is practically sensitive, layer or it may be incorporated in the powder containing the coupling component. In any. of these cases the exposed print is developed simply by gentle heating which causes the hydrated salt to dissociate, so that the water vapour liberated brings about the developmental the print, which print is of course dry. p p

In any a of these ways the advantage is dry and which, owing tothe absence of wetting, preservesa sharp line. If, however, for any reason-it is desired to use the semi-dry developing process, thismay also be done by using an ordinary developing machine containing water. In

this case it may be found advantageous to add V 1a substance such as the salt of a weakjacid with a strong base'either to the'sensitive layer or to the coupling component; a substance of this type v has the property of acting as a coupling acceler ator and-also its saline'nature' helps to prevent the line from running? Altematively, instead e of using water alone in the developing machine,

a substance which prevents the line from run "ning,' such as potassium sulphate, or sodium chlorideor a substance whichnot only prevents the line from running" but also acts as a coupling accelerator, such as sodium acetate, may

be dissolved in the water used for the developer. If it isdesiredto carry out the development by this semi-dry process, namely, using an aqueous salt solution on a developing machine, this has the jg'reatadvantage over the ordinary semi-dry developer with a developingmachine in that the developer used is merely the solution of sodium acetateor potassium sulphate or the like which 'has the property of keeping indefinitely and does not deteriorate like the ordinary developers which contain readily oxidisable or otherwise unstable substances. If, however, it is desired for any reason tofuse a developer containing an alkali or to develop under alkaline conditions, this may also bedone according to the present in- I vention, as thel; compounds capable of coupling been referred to; Also, for example, it may be desired to dilute the couplingcomponent, such T,

as p-naphthol, with"an inert substance such as starch or dextrinr. Alternatively, other substances m ay be mixed with the couplingcompov nent in order to increase thespee'd of coupling, sodiumtartrate .being a suitable substance for this purpose. Furthermore, the coupling component may be any of the well-known coupling components, such as a phenol or base, examples being p-naphthol or phloroglucinol.

The followingexamples illustrate how the invention may be carried out in practice, but it is obvious that the invention is capable of a great variety ofmethods of application and is in no way limited ,to the .details given in these examples:

Example 1.The paper is coated witha solution of 60grams of zinc chloride, double salt of 5-benzoyl-amino-1:4-diethoxy-2-diazonlum chloride, 30 grams of aluminium sulphate made up to 1000 cc. 'with .water and dried. After drying. the paper is dusted over. the entire sensitive surface with a powder composed of 60 grams of flour and -l0 grams of phloroglucinol.

excess of powder removed by The paper. may then be stored for a considerable, length of vtime before exposure to light and de-' velopment. After exposure to light the paper can be developed either by exposure to steam or by'the gelatine methodalready herein de-- scribed,-or by the semi-drymeth od; A suitable developer I for. development by the semi-dry method is one containing- 100' grams of sodium acetate crystals, and 2- grams of tartaric acid in 1000 cc; offwater; It will be seen that this developer is one which will keep indefinitely. Example 2. -The paper is coated with a lightvsensitiye layer as described in Example 1 and drieda After drying', the paper is dusted over the entire sensitive, surface with a powder composed 'of 130 gramsfof flour; 1!) grams "of phloroglucinol and soggrams offsodium'benz'oate- After dusting with the pow nflthepowder iswell rubbed on and into the surface of the paper and excess of powder removed by'brushing. The paper may then, be stored foria considerable length of time before exposure to, light snddevelopment. In this case developmentof' the'ptintban be carried out simply by contact with water'which'can idvantageous1y be applied in an ordinary developing machine. Many diazo compounds willcouple ,under neutral or acid conditions at 15.52pm: is far too slow to be of any use in diazotype papers After dusting with the powder, the powder .Lr well rubbed on and into the surface of the paper and of this kind, and I declare that when in my claims I use the words a diazo compound capable of coupling in neutral or acid 'conditions I mean a diazo compound which under neutral or acid conditions will couple with such speed that the diazo compound' and coupling component could not be put together. in the light sensitive layer without coupling prematurely, either during drying or storage, whether a dehydration has taken place or not. l

What I claim and desire to secure by Letters Patent is: v I v r 1. As a new article of manufacture, a lightsensitive element comprising a carrier coated with a dry, light-sensitive-layer containingadiazo compound capable of coupling when treated with a coupling component and moisture in the absence of alkaline substances,- said element car- *rjying, adhered to its surface in the form of a dry powder or dust, a coating containing the coupling component. 1

/ 2'. As a new article, of manufacture, a lightsensitive element comprising acarrier coated with a dry, light-sensitive layer containing a diazo compound capable'of coupling when treated with a' coupling-component and moisture in the,

absence of alkaline substances, said element carsensitive element comprising a -carrier coated with a dry, light-sensitive layercontaining adiazo compound capable of coupling when treated with a coupling component and moisture in the absence of alkaline substances, said element carrying, adhered to its surface in the form of a dry powder ordust, a coating containing the coupling component, .the article also containing a hydrated salt capable of liberating moisture.

4. As a new article of manufacture, acarrier coated with a dry, light-sensitive layer containing a diazo compoundcapable of coupling when treated with a coupling component and moisture in the absence of alkaline substances, said lightsensitive layer carrying, adhered to its surface in the form of a dry powder or dust, a coating containing the coupling component.

5. A process for preparing diazotype photographic papers by coating a paper with a light-sensitive layer containing a diazo compound capable of coupling when treated with a coupling component and moisture in the absence of alkaline substances, drying the paper, and subsequently coating the paper with a substantially dry coupling component so that it adheres to thejsurface of the sensitive layer, exposing the paper to light behind the pattern it is desired to reproduce, and subsequentlydeveloping by treatment with moisture.

6. A process for preparing diazotype photographic prints by coating a paper with a lightsensitive layer containing a diazo compound capable of coupling when treated with a coupling component and moisture in the absence oi. alkaline substances, drying the paper, subsequently dusting the paper with a coupling component so that it adheres to the surface of the sensitive layer, exposing the paper to light behind the pattern it is desired toreproduce, and subsequently developing by treatment with moisture.

7. A process for preparing diazotype photographic prints by coating apaper with a lightsensitive layer containing a diazo compound capable of coupling when treated with acoupling component and moisture in the absence of alkaline substances, drying the paper, subsequently dusting the paper with a coupling component so that it adheres to the surface of the sensitive f layer, exposing the paper to light behindthe pattern it is desired to reproduce, and subsequently developing by treatment with water vapour at an elevated temperature.

8. A process of developing diazotype photographic prints by coating a paper with a lightsensitive layer containing a diazo compoun'dcapable of coupling when treated with a, coupling 1 component and moisture in the absence of alkaline substances, drying the paper, subsequently dusting the paper with a coupling component so that it adheres to the surface of the sensitive layer, exposing the paper to light behind the patf tern it is desired to reproduce, and subsequently developing by applying, in a developing machine, an aqueous solution of a the line from running. M

9. A process of developing diazotype photographic prints by coating a paper with a lightneutral salt to prevent sensitive layer containing a diazo compound capable of coupling when treated with a coupling component and moisture'in the absence of alkaline substances, drying the paper, subsequently dusting the paper with a coupling component so that it adheres tothe surface of the sensitive layer, exposing the paper to light behind the pattern it is desired to reproduce, and subsequently. developing by applying in a developingmachine an aqueous solution of a coupling accelerator.

WERNER PAUL LEUCH.