DE2325579C2 - Process for making diazotype copies - Google Patents

Description

The present invention relates to a method according to the preamble of claim 1.

In the diazotype process, dip in J. Kosars book "Light-Sensitive Systems", edited by John Wiley and Sons Ine, New York / London / Sydney (1965), described in detail on pages 194 f., two different systems are well known

In the dry or ammonia process, a diazotype material is used in which a photosensitive diazonium compound and a coupling component are present in one layer. This? Layer also contains an acid stabilizer. After imagewise exposure, this material becomes developed by the action of wet ammonia gas, so that the diazonium compound remaining on the unexposed parts couples with the coupling component and gives an azo dye.

The unpleasant and pungent smell of ammonia is the main disadvantage of this method. To To avoid too much ammonia gas from entering the work area, the copiers used in this process should be equipped with an exhaust system. However, the copies still smell for a long time Time after ammonia.

In the semi-wet process, a diazotype material is used, the photosensitive layer of which is only the Diazonium compound, either with or without a stabilizing agent and other additives, includes die Copy is developed by applying a thin layer of a buffered aqueous solution of a coupling component evenly over the photosensitive layer is distributed.

In practice, the amount of coupling component solution or developer used is 7 to 8 cm ³ per m ² per side. This amount is necessary to ensure that the developer is evenly applied and that the

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65 ne to achieve fast and complete development with the usual developing devices and diazotype materials. In general it will be almost the same Amount of developer also applied to the back of the copter material to prevent the material from curling or curling.

A copy developed this way contains a lot of moisture. A few copies can be air-dried, but if you have a large number needs to make copies one by one, a drying device is indispensable. Such a drying device requires a high heating capacity, especially in high-speed copiers. In addition, it takes a considerable amount of time for the dryer to reach the required drying temperature cause undesirable waiting times before the copier can be used. For this Reason has been looking for a development process for a long time with which one dry or something as well as making dry copies, but without the disadvantages of the ammonia process

For this purpose it is proposed in US Pat. No. 18 41 653 to use the developer liquid Apply the help of press rollers. An excess of developer is applied by means of two rollers covered by rubber, and this is then immediately removed again from the same rollers. According to this patent, those produced in this way appear to be Copies practically dry. In reality, however, the developer is completely into the diazotype material has penetrated so that it contains a considerable amount of moisture. Therefore, a drying device is indispensable in high-speed copiers.

Another solution was proposed in GB-PS 11 43 702. According to the process described therein, a two-part diazotype material is used, just as in the ammonia process. However, the development is carried out by applying a regulated amount of a maximum of 3 cm ³ per m ^{2 of} an alkaline liquid that is at least et>. J contains 20% of an aliphatic amine

The copies obtained in this way are instantly dry, but they feel a little bold. Another disadvantage is the relatively slow development caused by the fact that in general slowly coupling diazonium compounds are used in the two-part material, and presumably also because the viscous developer penetrates the material to be developed rather slowly

The object of the present invention is now to provide a method for making copies with a one-component diazotype material that works rpsch and with which you can immediately get dry copies that are odorless and that do not feel greasy. The invention relates to the copying process specified in the claims.

The copies produced according to the invention immediately feel dry; the small amount of moisture that has been applied evaporates very quickly by itself, so that no drying device is necessary even with high-speed copiers.

For the process according to the invention, both the known alkaline developer as a developer weakly acidic to weakly alkaline developers can also be used. Preferably, however, the weakly acidic to weakly alkaline EnI winders are used, which have a pH value between 5.5 and 8 because they have a better shelf life.

Such developers are for example in the GBPS 9 57 836. It is of course also possible to use other buffers than those mentioned in this patent specification as long as they give the desired pH and have a sufficient buffering effect. Specific examples of suitable buffers are the alkali metal, magnesium and ammonium salts of succinic acid, Glutaric acid, adipic acid, ^ -methyladipic acid, Maleic acid, malonic acid and citric acid.

In the present invention, a developer is used which is more concentrated than that in the above-mentioned patents described developer. This makes it possible despite the small amount of developer applied to apply about the same amount of coupling component as in the known semi-wet development. This ensures rapid and complete development

According to GB-PS 9 57 836, the amount of phloroglucinol is used as a coupling component in this case was used, at most about 50 millimoles per liter and the amount of buffer salt! 50-650 millimoles per liter. In the developer used in the present invention the amount of coupling component is 0.1-0.6 mol per liter and the amount of buffer salt 0.5-3 g-equivalents per liter.

In CH-PS 4 16 318 it is stated that when using large amounts of buffer salt on the surface of the developer treated diazotype material layers an undesirable crystal layer is formed. It is also mentioned that concentrated developer solutions penetrate the photosensitive layer worse and thereby become slow and incomplete Lead development. Contrary to this prejudice regarding the use of more concentrated developer solutions however, in the process of the present invention, copies of excellent image density with high Maintain development speed.

The developer can also contain common substances to prevent yellowing, antioxidants, Contains development accelerators and wetting agents.

In addition to phloroglucinol, which is preferably used as a coupling component, can of course also other coupling components, such as resorcinol, optionally in conjunction with phloroglucinol, are used will.

In the method according to the invention, one-component diazotype materials, containing fast coupling diazonium compounds is used.

When using such diazonium compounds, rapid and complete development takes place, as well as when using the aforementioned neutral to weakly acidic developers.

Therefore the diazo layer contains a diazonium compound, which has a stronger coupling activity in vitro possesses as p-diazo-o-chloro-diethylaniline. This definition the coupling effect is given in GB-PS 9 57 836.

Such fast coupling diazonium compounds are z. B. in the aforementioned patents as well mentioned in GB-PS 9 57 838. For example, the following compounds are preferably used:

1 - Diazo-4-benzoylamino-2,5-dibutoxy-benzene
1 - diazo-2,5-dii.thoxy-4- (4'-methoxy) -phenyl-

benzene
1-diazo-2,5-dimethc / .y-4- (4'-methyl) -phenyl-

thio-benzene

1-Diazo-2 ^ -diethoKy-4- (4'-methyl) -phenylthio-benzene

oxy-6-chloro-benzene
1 -Diazo - ^ - dimethylamino-S - ^ '- chlorJ-phen-

oxy-2-chloro-beny.ol

1-Diazo-2- (ethoxycarbonyl) (benzyl) amino-4- (methyl) (cyclohexyl) amino-3-methoxybenzene
ίο 1 -Diazo-4-benzoyIamino-2- (ethoxycarbony!)

(methyl) amino-5-methoxy-benzene
1 -Diazo-2- (ethoxycarbonyl) (methyl) amino -
5-methoxy-4- (4'-methyl) -phenylthio-benzene,

For the reason given below, the diazonium compounds are preferably in the form of a readily water-soluble salt, e.g. B. as hydrogen sulfate or as chloride, used. The diazo layer can contain several diazonium compounds. In addition, also the customary auxiliaries _w j _e acids and stabilizing agents, such. B. the sodium salt of 13.6-naphthalenetrisulfonic acid, reducing agent or thioureas, be present.

The photosensitive layers described in British Patent No. 9 57 836, in which the diazonium compound is present in a hydrophilic layer of 4 to 5 μm, are very suitable for development by the process according to the invention whose carrier material consists of paper, which can optionally be precoated, part of the diazonium compound is located much deeper in the material. This is due to the fact that the diazonium compound is applied in an amount of diazo solution of 10 to 15 cm ³ per m ² . This can cause the diazonium compound to penetrate deeply into the material.

Since the development according to the method according to the invention is only carried out with an amount of developer of 1.5-4.5 cm ³ per m ² , the coupling component cannot penetrate so deeply into the material. As a result, development does not take place completely. In general, only about 70% of the diazonium compound is converted into azo dyes.

This problem can be solved by first coating the paper with a hydrophobic barrier layer and then applying thereon a hydrophilic layer of the desired thickness The diazonium compound can be applied either at the same time as the hydrophilic layer or afterwards. That way will prevents the diazonium compound from penetrating too deeply. The composition of the material is the same then that of the diazotype material described in British Patent 9 57 836.

However, it has now been found that too deep penetration of the diazonium compound can also be prevented by treating the material with a smaller amount of diazonium solution which contains a diazonium compound in a correspondingly higher concentration, e.g. 0.05 to 0 A suitable amount is e.g. about 2-8 cm ³ per m ² , preferably about 3 cm ³ per m ^2. In this way, the diazonium compound penetrates about just as deeply and in the same way like the coupling component: materials made photosensitive in this way are almost completely developed (95-100%).

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To show the effect of this photosensitizing, a series of diazotype papers, which ^{had been coated in a known manner with 10-15 cm 3} per m ² , and a series of diazotype papers which had been coated according to the invention with about 3 cm ³ per m ² , completely developed with the developer solution described in Example I. Parts were then cut out of the developed materials so that the cross-section of the azo dye layers could be viewed under a microscope. It turned out that the thickness of each dye layer was very different in places. The layer thickness was therefore measured at many different points and the arithmetic mean was calculated from the results of these measurements. This average is referred to here as the average maximum layer thickness. The diazotype papers coated with 10-15 cm ³ per m ² had an average maximum layer thickness of 9-12 μm.

The average maximum layer thickness of the transparency paper, which according to the invention is about 3 cm ^! per m ² coated was 5.5 - 7.5 µm.

The diazotype papers used in the present invention preferably have an average maximum Layer thickness of at most about 8 μm, in particular at most about 7 μm.

If the diazo layer is applied directly to the paper, the surface structure of the paper can change on the copy in the form of an uneven distribution of the azo dye. This can be done by prevent the paper from being precoated in a known manner. Such a layer consists in generally an inorganic pigment such as silicon oxide. Aluminum oxide, a metal silicate, or a organic pigment such as starch and rice starch. j5 in a binder such as casein, polyvinyl alcohol, or polyvinyl acetate.

It has surprisingly been found that even with materials in which the diazonium compound is present in a hydrophilic layer, the coating with a diazonium salt solution in an amount of 2-6 cm ³ per m ² instead of the 8-15 cm customary for these materials ³ per m ^{2 has a} beneficial effect on the development speed and the complete development of the diazotype material.

As can be seen from the cut surfaces of the developed material, the diazonium compound was also in this case closer to the surface when the material was coated ^{at 2-6 cm 3} per m ^2. This allows the coupling component to reach the diazonium compound more easily.

The amount of developer involved in developing it the diazo layer is applied depends on the surface structure, the hydrophilic behavior and the porosity of the diazotype material to be developed. One a smoother layer absorbs less developer than a slightly coarser layer.

On painted materials whose carrier is made of a synthetic film, e.g. B. a polyester film, or a transparent paper, which is provided with a hydrophilic layer and optionally with a hydrophobic intermediate layer, for example a superficially saponified cellulose acetate layer, an amount of 1.5-3.0 cm ³ per m ^{2 is} applied. These diazotype materials contain a larger amount of diazonium compound per unit surface area than diazotype papers. A certain minimum amount of developer must be applied to fully develop these materials. Compared to the appropriate amount to be applied to which the developing device for such diazotype materials has been set, a larger amount is applied to papers, which means that an excess of coupling component is applied to diazotype paper.

As a result, the amount of developer that is applied to ordinary, opaque materials with a paper carrier with or without precoating is 2.5-4.5 cm 'per m ² . preferably 2.5 - 3.5 cm 'per m ^? .

The mentioned 'minimum quantities result from the need to distribute the developer evenly over the Spread the diazo layer while moistening the entire surface. The upper limits will be of this dictates that the material must feel dry to the touch when it leaves the processor.

Various devices are already in the literature! genes have been described, iiiii (those it isi. cii'ic to distribute such a small amount of liquid evenly on a surface. The best results are achieved in the method according to the invention with the device described below, This means that all of the above materials can be processed well and the developer can be applied evenly and apply continuously.

This device is shown schematically in the drawing. 1 is a metering roller which is provided with a structured surface and which is partially immersed in the developer 3. The structure can be obtained by providing the roller with a spiral groove over its entire length. 2 is the applicator roller. The surface is elastic, non-porous, and has a suitable hardness, generally 10-15 '^;

SI'iOi ci iafic A, preferably 2 j - 3j Sliore-Härit: A. 4 ^:

is a pressure plate in which preferably at least the part that comes into contact with the applicator roller is made of an elastic material, e.g. B. polytetrafluoroethylene, is made. About the formation of a liquid meniscus and the wetting of the back of the copy counteracting this is the edge of the pressure plate preferably provided with U-shaped notches.

A device can also be attached that lifts the printing plate from the application roller, if there is no copy between this platen and the platen.

A pressure roller can also be used in place of the pressure plate can be used, the surface of which is provided with bumps to prevent the printing roller from becoming wet and thereby prevent the reverse side of the developed material from becoming wet.

5 and 6 are the lead-in and lead-out slots for the Diazotype material. 7 is the diazotype material to be developed. 8 is a case used to house the Prevent evaporation of water from the developer.

The copy to be developed is between the applicator roller 2 and the pressure plate 4 with the photosensitive Side down.

When the device is in operation, the metering roller 1 applies developer to the applicator roller 2 brought. This takes up part of the developer liquid and conveys it to the copy to be developed. The copy picks up part of the developer from roller 2, with the picked up amount below depends on the material to be developed The amount of developer applied to a certain material, z. B. paper, is applied depends on, among other things

the surface structure of the metering roller 1, the hardness and the hydrophilic behavior of the upper and the application roller: e 2 from. All these factors must therefore be related to each other, and it many suitable combinations are possible. It was z. B. manufactured a developing device whose Metering roller was provided with a groove of 25 μm deep and a filler spacing of 0.3 mm. The groove had a triangular cross-section. The upper width was 50 μm. The surface of the applicator roller existed made of a polished rubber with a Ha.tc of 25 ° Shore A. The pressure between the metering roller and The application roller was 7 g per running millimeter, and the pressure between the pressure plate and the application roller was 4 g per running millimeter.

With this developing device a developer application was obtained which remained constant up to a transport speed of 20 m / min of the material to be developed, namely / w: sc! Ieri 3, j unu 4 i_iii ^; per m- for paper and between 1.5 and 2 cm ¹ per inch for film material.

In general, the pressure between the pressure plate and application roller should be 2-10 g / mm, preferably 3-5 g / mm. There should be a certain minimum pressure in order to obtain good, even humidification. If the pressure is too high, too little developer will be applied to the diazotype material. The application needs should be coated with a material which: i. l · ι. On a maximum of 50 'Shore A. preferably 25-J5 Snore i ι sits This is necessary in order to obtain an equal, permissible moistening with material with thickness differences and with tolerances of the pressure plate and the rollers used. The pressure between the application roller 2 and the metering roller I is J-9 g / mm, preferably 5.5 g / mm. The surface structure of Posierungswal / edh the Gesamtquerschniit of the depressions running pm Millimek: should be finally selected such that ^be: the pressure used, the desired amount is applied to developer. This structure should not be too coarse, otherwise it would be more or less visible on the final copy, because the developer would then not be able to distribute himself sufficiently evenly over the application roller. In the above-mentioned device, the total deepening of the grooves over the longitudinal section of the roller was approximately 2 0μΓη ² / ηΐΓη. Usually, the cross section of the depressions over the longitudinal section of the roller is 1000-4000 μπΊ ² / ΐπΓη.

In the method according to the invention, the developer is preferably applied only to the diazo layer. Therefore, the diazo paper tends to curl backwards, i.e. H. with the light-sensitive side Outside. This wave disappears after a short time. If necessary, it can be reduced or the duration of this Can be shortened. The paper can e.g. B. can be made more water repellent by making it previously coated; this practically forms a barrier layer on the surface of the paper. In this way this also prevents the diazonium compound from penetrating too deeply

Example I.

A carrier paper for the diazotype process was precoated on one side in a known manner. These Layer consisted of:

10 g of a crystalline silicon oxide with a particle size of 5 μm.

6cm ^J

an emulsion of 50 wt .-% polyvinyl acetate, which was made up with water to a total of 100 cm ³ .

The coating was carried out by 15 cm ^3/2 this mixture was evenly distributed over the paper and this is then dried. The precoated side was then made photosensitive by applying 3 cmVm ^{2 of} a 0.14 molar diazo solution in water evenly to the surface and drying. A mixture of two diazonium compounds was used in the diazo solution, namely:

4-Dimethylamine-3- (4'-chloro) -phenoxy-b-chlorobenzene-diazonium hydrogen sulfate and

2.5-diethoxy-4- (4'-methyl) -phenylthio-benzenediazonium hydrogen sulfate

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Diazotype material thus obtained was exposed through a transparent original and read. 'id developed by adding 3 cm / m ^{2 of} a solution. -r the following composition with the developing device shown in the drawing evenly distributed on the diazo layer:

260 g dipotassium succinate (calculated anhydrous)
25 g phloroglucinol 2 aq.
6 g resorcinol
m I g wetting agent
1000 cm ^{1 of} water.

The pH., R ·; The solution was made by adding Succinic acid adjusted to 6.8. The solution contained 1.5 moles of succinate and 0.2 moles of coupling component per lit'.T.

Immediately after developing the copy felt dry and showed a strong black image that way contained almost no unreacted diazonium compound.

Example Il

i *> A cellulose acetate film layer of about 20 g / m ² applied to natural transparent paper of about 80 g / m ² . was superficially hydrolyzed to a depth of about 5 μm by treating it with a solution of KOH in a mixture of water and methanol. After the chemicals used for the hydrolysis had been removed by washing with water and the paper was dried, it was ^{made photosensitive by applying 3 cm 3 cm 2 of} a 0.35 molar solution of a diazonium salt to the hydrolyzed side of the paper. A similar result can be achieved if an excess of diazo solution is applied and it is removed again after about 1 second, for example with a high pressure air blower.

4-Benzoylamino-2- (ethoxycarbonyl) (methyl) amino-5-methoxy-benzene-diazonium hydrogen sulfate was used as the diazonium salt. The diazotype material obtained was exposed imagewise and developed in the manner described in Example I. There was 2.5 cm ³ / m ² Developer applied. The copy obtained in this way immediately felt dry and showed a strong purple to brown image with very good UV absorption on a clear background

Example III

A polyester film was provided with a layer of 10 g / m ² of cellulose acetate and a non-crystalline silicon oxide in a weight ratio of 3: 1. This splint was superficially saponified in the manner described in Example II. The resulting support was then photosensitive as in Example II. The diazotype material obtained in this way was exposed imagewise and developed with the device shown in the drawing by applying 2 cm-Vm ^{2 of} the developing solution described in Example I to the diazo layer. The same results as in Example II were obtained.

1 sheet of drawings

Claims (3)

Patent claims: I. Process for the production of copies, in which a diazotype material which contains a diazonium compound which couples faster in vitro than ^ diazo-a-chloro-NN-diethylaniline, exposed under an original and developed with a solution which contains a coupling component and Contains buffer salts and has a pH of 5.5 to 8, characterized in that a diazotype material is used whose photosensitive layer is at most 8 mm thick and that an aqueous solution of 0.1 to 0.6 mol Coupling component and 0.5 to 3 g-equivalents of buffer salt per liter, in an amount of 1.5 to 4.5 cm ^J / m ² on the light-sensitive side of the diazotype material 2. The method according to claim 1, characterized in that a diazotype material is used del, which by evenly applying 2 to 8 cmVm ^{2 of} an aqueous solution of a diazonium compound has been made photosensitive on the surface of the material 3. The method according to claim 2, characterized in that an aqueous solution is used, which contains 0.05 to 0.6 mol of diazonium compound per liter