US2114468A - Processes for copying on positive diazotype layers - Google Patents

Description

" type layers.

Patented Apr. lb, v

' I PROCESSES FOR COPYING 0N POSITIVE 1 DIAZOTYPE LAYERS Lodewljk Iieter Frans van der Grinten, Venlo, Netherlands, assignor to Naamlooze Vermontschap Chemlsche FabriekL. van der Grinten, Venlo, Netherlands, a limited liability commay No Drawing. Application October 25, 1935, Se-

rial No. 46,825. In the Netherlands August 23,

10 Claims.

Positive diazotype layers have so far mainly been used for the copying of line-drawings by means of transmitted rays and only seldom for the preparation of half-tone copies (for example from screened half-tone originals) and reflex copies.

For the, last-named purposes special measures have'been taken (with regard to diazotype halftone copies see the German patent specification 577,400; with regard to diazotype reflex processes see the British patent specification 425,126). Without these special measures up to the present sumciently good half-tone and reflex copies could not be obtained with mosttypes of 'diazo- It is true that Khgel in German patent specification 302,786 described the making of reflex' copies by means of dlazo layers. In general, however, the practical resultsobtained by this process are poor. Only in one favourable case, viz. when the 1 diam-2 oxynaphthalenesulphonic acid according to the example of the said specification is used somewhat better results are obtained. Temporarily it has also been used for this purpose technically, but only to a moderate extent and thisprocess could notlae worked successfully technically in the long run and has been replaced by the well known Aluna process (a combination of silver photography and the diazotype process). Poor and practically not suitable for use are the results obtained in the process of the German patent specification 302,786 when carried out with a class of diazo compounds which contain an amino group in the nucleus containing the disco group and yet in this class occur compounds which otherwise are the most suitable for the diazotype process. An explanation for this can be found from J. M. Eder, Zeitschriit filr WlSSEXlSDhfift-l liche Photographic, volume 33, part 1, page 12 and from Ikuzo Fukushima and Mason Horio in Journ. Soc. Chem. Ind. Japan 1931, pages 3873-- 372 B. As described in these publications, sensitive diazo compounds havea great absorptive power .for the active rays which the phenols, formed therefrom by the exposure do not. exhiblt, that is to say not to such extent that in general this would influence the course of the reaction. This involves a particular type of progressive effect which Eder calls Auirollen (see 'Eder, loo. cit. line 19) and the circumstance that in practice the dlazo photolysis is often a reaction of the zero-order (German: Nullter' 0rdnung.) which-fies will be--clear--mel:es the diazotype layers, especially those withamino-diazo compounds unfit for the reflex copying process .sitive layer. first strikes the suriace or face of the sensitive layer, and in so doing causes the sensitive sub-' unless further measures be adapted and involves the steep graduation, which is aconsequence of this course of reaction, and consequently a poor reproduction of halt tones.

The term Aufrollen as used in this connection refers to the action of the light upon the sen- Upon exposure to light, the light layer underneath is attacked to any-substantial extent. More particularly when working with thicker or more concentrated layers'which often are preferred for half-tone reproduction on account of their, high maximal optical density and for reflex copies on account of their higher contrast, the said Aufroll efiect etc. was strong. Now the above-named-methods involving certain complications (in the diazotype half-tone process a screened half-tone original must be used; in the processof German patent specifi-' cation 577,400 a specially graduated original must be used; in the reflex process of the British patent specification 425,126 a screen or the like must be used), there exists a need for new methods which wlll'rnake it possible to use successfully the positive diazotype layers with andno-diazo. compounds, which are so much prefeared for other reasons, for half-tone and reflex copying. As already stated, without the known special measures, the course of the photolysis, e. g. the "AufrolP character of these d'iazo compounds were a hindrance in this respect.

It has now been found that when working with positive diazotype layers with diazo compounds containing amino groups in the nucleus, the use of the rays falling in the ranges of low absorp-- tion which are i'ound in that part of the spectrum in whichthesediazo compounds show substantial light sensitiveness, is practicable-for obtcne copies are meant copies having pictures in which thehali-to'ne or continuous tone effect is not obtained by any kind of screening but by a" difference in optical density. For the purposes the use of rays falling in the ranges or high 'taining true half-tone and reflex copies of sufi ficient quality. By true half-tone or continuous absorption of the diazo compounds in question. Both the ranges which according to the invention are practicable and those which. have to be avoided fall with difierent diazo compounds in different parts of the spectrum, mostly, however, with relatively small deviations with diazo compounds of chemically related constitution.

Practicallyworkable ranges of low absorption and also the ranges of high absorption which are to be eliminated are, with the following examples of diazo compounds with amino groups, situated as follows:

Wave

Wavelengths Diazo compounds 1051532350 to be avoided Paradiazobanzylaniline 2850-3200 2850 a. shorter Paradiazodiphenylamine 2000-3200 2900 a. shorter 3diazocarbazol 4200-5000 4200 a. shorter.

4 diaz-3-(i-diethoxy-benzoylaniline 4200-4900 4200 a. shorter.

Orthodiazodimethylaniline 2900-3700 2900 a. shorter 4800-5800 3700-4800.&.

Paradiazo dimethylaniline 28500200 2850 a. shorter 4200-4000 3200-4200 3..

Paradiazo dimethylrrictatoluidine--.. 2850-3200 2850 a. shorter 4200-5000 3200-4200 A.

Paradiazo-orthochlor-dimetliylaniline 2850-3200 2850 a. shorter Paradiazo dimethylanilinemetasul- 2850-3200 2850 a. shorter Phonic 4150-4800 3200-4150 A.

Paradiazo diethylaniline 2800-3200 2800 a. shorter I 42005000 3200-4200 ll. Pziiradiazo1 pypegglyll; (or1 (1183}? 2850-8200 2850 a. shorter 1enzy-. me y enzy-, e y-, 2004 benzyl-, ethyl chlor 4 benzyl-, 420M900 3 200 (etc) aniline.

Paradiazo diphenylaniline 2900-3200 2900 a. shorter The foregoing wave lengths are expressed in the angstrom unit, 5 4 01 1 mm.

copy from an original executed in red on a yellow back ground-and consequently also one cannot apply the process of the invention successfully thereto. Up to the present, such originals can only be copied by means of other processes like those using silver compounds.

Apart from the above-mentioned ranges to be used" and ranges to be avoided there also are the ranges (which with most diazo compounds include wave lengths above approidmately 5000 A. units, with a few above approximately 5700 A. units) in which the diazo compounds do not show practical sensitiveness. The rays in this range can be applied in combination with the others without decreasing the eflect of the invention. When using sources which emit these rays it consequently is not necessary to filter them out, provided that the heating of the irradiated copying system caused by these rays is not objectionable (for the same reasons one also would eventually filter out the infra-red rays). When selecting or searching for a suitable source of rays it, however, can be useful to choose the source so that these last named rays are emitted to a slight extent-only because substantial emission of these rays would only involve useless loss of energy.

For the carrying out 01 the invention the question of the procurement of the suitable rays is of importance. Sources which exclusively or mainly emit rays in a relatively narrow range of the spectrum are seldom encountered, particularly in the range of sensitivity of the diazo compounds usually employed; therefore often undesirable rays have to be filtered out. I

Experimentally and also practically one can in example obtain automatically suitable filtering by means of the same diazo compound as the one which forms the diazotype layer. As the diazo compound is decomposed when acting as a filter, one uses a container having parallel windows at each side, through which the diazo solution flows, or a movingfilm coated with the diazo compound or the like. Suitable light-stable filters are preferred inpractice. By way of example the following combinations are indicated:

Diazo compound Source oi radiation Filter Paradiazo diphenylemlne Arc-lamp for copying purposes Arc-lamp for copying purposes- Bright sunlight Strong incandescent lamp Cadmium vapour lamp oi Uviol sion). High pressure mercury vapour High pressure mercury' vapour Schott GO 3 (x) or "Corning (xx) Noviol A No. 038.

Wratten-' (xxx 2A. Wratten" xxx N with pure carbon electrodes.

Without; or with Col-mug" (xx) Red purple Corex A No. 986 filter 5 mm. thick.

mm. of an aqueous solution of 0.01% K2Cl04 in 0,05 N.KOH. Wfiiifimut; or with quinine-sulphate glass (with high U. V. transmislamp oi Uviol glass.

lamp of glass with low U. V. transmission. Zinc vapour lamp oi Uvlol glass. 10 mm. oi an aqueous solution of 0,01% K1CrO4'in 0,05 N.KOH. Zinc vapour lamp of Uviol glass... Without; or with 10 mm. oi an aqueous solution of 0,01% K2Cl'04 in 0.05 N.KOH.

Literature-Catalogue oi the firm Schott c.

( ena. (xx) Literature-Catalogue oi "Glass color filters oi the Corning Glass Works, Corning, N. Y. xxx) Literature-Catalogue of the firm EastmanKodak 00., Rochester, N. Y. (Wrattenfilter).

It might be useful to state here that the results naturally also depend on the originals used and that there exist originals which at present cannot in practice be copied by means of the diazotype process. Thus for example one cannot, or only rather with difilculty, obtain a diazotype From the point of View of efliciency it is, as stated already, advantageous 'for the practical application of the invention to use such a combination of a diazo type layer and a source of radiation that as much as possible the preferred and as little as possible the undesirable rays are 0. 4. Schott (x) G6 7 or/resp. both.

GGll.

aliases emitted by the source. When a source of radiation is powerful in the preferred range as is for example the case with the known high pressure mercury vapour lamps, more specifically with the super high pressure lamp of B01 (see. Pieter Zeeman, Verhandlungen, edited by Martinus Nijstage-lighting and the like (see Osram, Lichtheft,

page 23, page 15) more specifically in combination with most of the diazo compounds having light sensitive diazo compound having. an amino groupin the nucleus and an absorption spectrum containing ranges with low absorption and ranges a tertiary amino group in the para position, which particular dlazo compounds are preferred on account of the high optical density obtainable therewith. With'this combination there can be obtained even without, although preferably with some filtering, with relatively short exposures good halt-tone and reflex copies. 'This so far has not been possible with these diazo compounds in the sources 01' radiation usually employed, viz, Cooper Hewitt lamp, arc-light or the sun. Already with a lamp of this kind of 1000 watts rather short exposures can be obtained for sheets of the size of a letter.

According to the invention filter layers can be combined with'the picture forming layer into one and the same sheet; For the purposes of the invention it is not necessary to carry out the entire irradiation exclusively with the preferred rays. One also can combine with it a partial irradiation with rays of the kind defined before as to be avoided. In this manner often ad'- vantageously special half-tone eilects or halftone corrections can be obtained and in the reflex copying process colourlem lights can be obtained in combination with good contrasts.

By way of example a reflex copy is made by means of a transparent sheet coated on one side with a solution of 15% para-diam ethyloenzylanilinechloride, which is located with its sensitive surface in contact with the original. The source oi radiation is a high pressure mercury vapour lamp of 1000 watts of low ultra-violet transmission with a vapour pressure oi 300 mm.

A quinine sulphate filter is inserted between the source of radiation and the copying system. The irradiation is continued until a test after development with a solution of 1% phlorogluclnol (azo dyestufi coupling component) and 2% sodium carbonate yields a positive picture on a. dark background, the optical density of which is reduced to approximately ,4; of its original value.

- Thereafter the irradiation is continued with a high pressure mercury vapour lamp of Uviol glass and without a filter, which gives an irradiation with substantial action at the wave length of 3650 .5. units. This same irradiation is'continued until a ,test yields upon development as described above a positive picture on a purely white transparent background. Then the entire copy is developed in this manner.

In general .it can be stated that rays tobe avoided when mixed with preferred rays do strongly disturb the typical working of them and -veloping the exposed layer by causing an azo dyewith high absorption to a radiation containing active rays which fall within said ranges of low absorption with the exclusion substantially of rays falling within said ranges of high absorption, and developing the exposed layer by causing. an azo dyestufl coupling component to react with said diazo compound so as to convert the diazo com pound into an azo dyestufl color and thereby pro duce the darker. parts or the print.

2. In the process of making directly from an original 9. diazotype print which is positive with respect to said original, the steps of exposing in contact with said original a layer containing a light sensitive diazo compound having an amino group in the nucleus and an absorption spectrum containing ranges of low absorption and ranges of high absorption to a source of radiation emitting substantially only active rays which 'iall within said ranges oflow absorption, and destuti coupling component to react with said diazo compound so as to convert the diazo compound into an azo dyestufi color'and thereby produce the darker parts oi'the print.

3. In the process of making directly. from an original a'diazotype print which is positive with respect to said original, the stepsof exposing in contact with said original a layer containing a lightsensitive diazo compound having an amino group in the nucleus and an absorption spectrum containing ranges of low absorption and ranges or high absorption through a filter of the type which substantially excludes those rays which fall within said ranges of high absorption to a radiation containing active rays which fall within said ranges of low absorption, and developing the exposed layer by causing an azo dyestuil coupling component to. react with said diazo compound so as to convert the diazo compound into an azo dyestuil color and thereby produce the darker parts of the print.

4. The process according .to claim 3 wherein the filter used is that which contains a substance having an absorption spectrum which is substan-- tially the same as that of the diazo compound present in said layer.

5. The process according to claim 3 wherein the filter used is that which contains a diazo compound oi the same chemical composition as that present in the sensitive layer. i

6. In the process of'making directly from an originals. diazotype print which is positive with respect to said original, the steps of exposing in contact with said original a layer containing a light sensitive diazc compound having an amino group in the nucleus and an absorption spectrum containing ranges of low absorption and ranges of high absorption to a radiation containing active rays which fall within said ranges of low absorption with the exclusion substantially of' rays falling within saidrange's of high absorption for the major portion of the total actinic eiiect, exposing still in the some contact with said original said layer to a radiation containing active rays which fall within said ranges of high absorptionior a lesser portion of the total aetinic -effect than that produced by the low absorption radiation, and developing the exposedlayer by causing an azo dyestui! coupling component to react with said diazo compound so as to convert the disco compoundintoan azo dyestufi color and thereby produce the darker parts of the print.

7. In the process of making directly from an original a diazotype print which is positive with respect to said original, the steps of exposing in contact with said original a layer containing a light sensitive diazo compound having a tertiary amino group in the nucleus and an absorption spectrum containing ranges with low absorption and ranges with high absorption to a radiation containing active rays which fall within said ranges of low absorption with the exclusion substantially of rays falling within said ranges of high absorption, and developing the exposed layer by causing an azo dyestufi coupling component to react with said diazo compound so 'as to convert the diazo compound into an azo dyestufi color and thereby produce the darker parts of the print.

8. In the process of making directly from an original a diazotype print which is positive with respect to said original, the steps of exposing in contact with said original a layer containing paradiazodiphenylamine to a radiation containing active rays corresponding substantially to those rays of wave lengths falling within the ranges of 2900-3200 A. and 4600-5300 A. with exclusion substantially of rays of wave lengths falling within the ranges shorter than 2900 A. and between 3200-4600 A, and developing the exposed layer by causing an azo dyestufi coupling component to react with said diazo compound so as to convert the diazo compound into an azo dyestufi' color and thereby produce the darker 'parts of the print.

9. In the process of making directly from an original a diazotype print which is positive with respect to said original, the steps of exposing in contact with said original a layer containing 4- diazo-3-6-diethoxybenzoylaniline to a radiation containing active rays corresponding substantially to those rays of .wave lengths falling within the range 4200-4900 A. with exclusion substantially of rays of a wave length shorter than 4200 5., and developing the exposed layer by causing an azo dyestufl coupling component to react with said diazo compound so as to convert the diazo compound into an azo dyestufi color spectrum with a high absorption below 2850 A.

and between 3200-4200 A. and with a low but appreciable absorption between 2850-3200 A. and

between 4200-4900 A. to a radiation containing active rays of wave lengths falling within the ranges of 2850-.3200 A. and 4200-4900 A. with ex- Q clusion substantially of rays of wave lengths less than 2850 A. and between 3200-4200 A, and developing the exposed layer by causing an azo dyestufi coupling component to react with said diazo compound so as to convert the diazo compound into an azo dyestufi color and thereby produce the darker parts of the print.

'LODEWIJK PIE'I'ER FRANS VAN DER GRINTEN..