DE1447916C3 - Process for making a moisture-proof, photosensitive planographic printing plate - Google Patents

Description

The use of diazo compounds for manufacture photosensitive planographic printing plates is already known. These diazo compounds are in at is applied in a known manner, for example from a solution to plates made of metal, plastic or paper. When exposing the photosensitive layer of the planographic printing plate applied in this way, for example through a negative, the exposed parts of the image are hardened and thus insoluble in the developing agent did. The unexposed parts of the layer are then removed with the aid of a developing agent detached.

From German Patent No. 11 18 606 are light-sensitive layers known for the photomechanical production of printing forms, the whole or partly of one or more light-sensitive ones which still carry at least one free hydroxyl group Esters of naphthoquinone-1,2-diazide-sulfonic acid on the one hand and containing at least 2 hydroxyl groups Organic compounds on the other hand exist, the two linked by a link X. Benzene and / or naphthalene nuclei contain, where X is a methylene group, one by one or two lower Alkyl radicals, aryl radicals or substituted aryl radicals substituted methylene group, a methylene group which one belongs to saturated, alicyclic system. sulfur or represents sulfur linked to oxygen and wherein the benzene and / or naphthalene nuclei in addition to the hydroxyl groups, they also contain halogen and / or alkyl and / or oxy and / or carbalkoxy radicals be able.

It has been found, however, that diazo compounds are known to be used for light-sensitive layers have an affinity for water which, if stored for a long time, especially in humid seasons, penetrates through the photosensitive layer and with intermediate layers or with the metal base plate can react. For example, if plates with K-.ZrFu interlayers, as they are in the U.S. Patent No. 29 46 683, used under the coating of the diazo compounds, so the penetration of moisture causes the bond between the photosensitive layer and the intermediate layer is weakened and the hardened photosensitive layer becomes stronger during the printing process replaces. Therefore, the shelf life of such diazo-presensitized planographic printing plates is limited unless care is taken to exclude moisture during storage.

In addition, they are based on the German interpretative document Il 18 606 used photosensitive compounds Can only be produced from specialty chemicals, which makes the production of such well-known light-sensitive chemicals Makes printing forms cumbersome and expensive. The object of the invention was, starting from as possible commercially available materials, moisture-proof, light-sensitive planographic printing plates with better storage stability can also be obtained in a humid atmosphere by developing agents known per se, such as Gum arabic, phosphoric acid, or sodium lauryl sulfonate, may have been developed.

The object is achieved according to the preceding claim 1.

According to the method according to the invention, planographic printing plates are obtained which are not only moisture-resistant and less sensitive to unwanted chemical

ao reactions during storage in the dark are, but also surprisingly highly sensitive to light are.

The reaction products used for the coating according to the invention are intermediate veras bonds, the addition compounds of the diazo condensation product and the phenolic compound or N-alkyl-5-sulfoanthranilic acid and are sufficiently resistant to the ingress of moisture that even under unfavorable conditions Conditions There is no staining and the like. The planographic printing plates that can be produced according to the invention are therefore not only for long storage, but also for long printing runs with high print runs particularly suitable.

If the diazo condensation product used according to the invention in an alkaline medium with the If the above-mentioned compounds are implemented, the products resinify and are ready for further processing unsuitable for light-sensitive layers on planographic printing plates. It is therefore essential that the reaction products used according to the invention from the condensation product and the further compound were obtained at a pH below 7.5.

Hydroxybenzophenones, acids with two phenolic groups, such as 4,4-bis (4'-hydroxyphenyl) valeric acid, resorcinol, diresorcinol, 1-naphthol-3-sulfonamide, sodium 2-naphthol-3,6-disulfonate or also N-alkyl-5-sulfoanthranilic acids be used. These compounds have water-solubility-increasing groups, such as carboxyl groups or sulfonic acid groups, and are therefore particularly suitable. As hydroxybenzophenones come the compounds 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-hydroxy-4,4'-dimethoxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, sodium 2,2'-dihydroxy-4,4'-dimethoxy-5-sulfobenzophenone, 2-Hydroxy-4-methoxybenzophenone-5-sulfonic acid, the trihydrate of this Acid and mixtures of the compounds mentioned are suitable. Is particularly preferred in this group the 2,2'-, 4,4'-tetrahydroxybenzophenone.

The condensation products used as starting materials are, for example, those of para-diazodi- phenylamine and formaldehyde, which are formed by the condensation of para-diazodiphenylamine sulfate and formaldehyde / zinc chloride or para-formaldehyde can be obtained.

In one embodiment according to the invention, the support plate is initially with the condensation product covered by diazodiphenylamine and formaldehyde and then with a solution of the treated phenolic compound, the solution preferably being 0.01-0.5% of the phenolic compound and preferably small amounts of additives, such as a wetting agent or a polyhydroxy acid, contains. The solution of the phenolic compound reacts with the condensation product of Diazodiphenylamine and formaldehyde depending on the concentration, temperature and the particular one used Solvent instantly or within a longer time of up to a few minutes or more. The reaction product on the plate is then the photohardenable compound and is with the backing plate firmly connected.

In another embodiment of the invention, the condensation product of diazodiphenylamine and formaldehyde reacted in a solvent with the further compound, after which this Solution is applied to the support plate and the solvent is evaporated. In this embodiment, there is usually a longer response time necessary.

As solvents in these reactions, for example, water, alcohols, such as low molecular weight Alkanols, alkyl acetate such as ethyl acetate and low molecular weight alkyl ketones can be used. Commercially available solvents can be used, the water contained therein being the desired Can encourage reaction. When solvents such as acetates and ketones are used, they should preferably contain water in an amount of 20 to 80% of the solvent. Methanol and Water are two preferred solvents. Mixtures of the solvents listed above can also be used be used.

Metal plates such as tin, aluminum and copper plates can also be used as base plates Plastic and paper sheets are used.

As intermediate layers between the photosensitive layer and a metal support plate various metal protective coatings are applied, such as aluminum oxide coatings, such as they can be found, for example, on anodized aluminum plates, reaction products of an aqueous Solution of soluble silicate with the metal substrate or reaction products of aqueous solutions of zirconium hexahalides, like potassium zirconium hexachloride, with the metal backing.

example 1

An aluminum offset plate 25 38 cm and 0.13 mm thick was successively _{coated with a K 2 ZrF 6} coating according to US Pat. No. 29 46 683 and then with a coating of a photosensitive diazo compound which is a condensation product of p-diazodiphenylamine and Was paraformaldehyde. An aqueous solution of 0.1% saponin and 0.5% 2,2 ', 4,4'-tetrahydroxy-benzophenone was then poured over the planographic printing plate. After a contact time between the solution and the plate of 1 to 2 seconds, the excess solution was spun off the plate and the plate was dried.

The plate produced in the above manner at 20 to 50 ° C. was stored in a chamber together with a number of other presensitized lithographic plates with a relative humidity of 90% exposed at around 32.5 ° C.

Panel A is a commercially available panel with a diazo coating.

Plate B is a plate with a layer of silicate between the aluminum base plate and a diazo layer is switched on. Their production is described in US Pat. No. 2,922,715.

Plate C is a plate with a K ₂ ZrF ₆ intermediate layer between the diazo coating and an aluminum base and differs from the plate prepared according to this example only in the light-sensitive layer used.

The test results can be found in the following table:

After treating panels A, B and C with 2,2 ', 4,4'-tetrahydroxy-benzophenone in the above described above, they remained in a satisfactory condition for 45 days when performed in the same way as have been air-conditioned above.

Anodized panels, mechanically grained panels, and even paper panels were also used in theirs Moisture resistance and overall performance improved when used with the reaction product were coated according to the invention.

35

40

45

Example 2

An aluminum offset plate 25 x 38 cm and 0.13 mm thick was successively _{treated with a K 2 ZrF 6} -

Plate from example 1

3 days satisfactory

7 days satisfactory

14 days satisfactory

28 days satisfactory

45 days satisfactory

satisfactory satisfactory

blotchy, unsatisfactory

blotchy, unsatisfactory

Corrosion on the plate, unsatisfactory

Corrosion on the plate, unsatisfactory stained, unsatisfactory

spotty, toning
unsatisfactory

Corrosion, toning on the
Plate, unsatisfactory
Corrosion, toning on the
Plate, unsatisfactory

unsatisfactory
excessive peeling of the layer
unsatisfactory
excessive peeling of the layer
unsatisfactory
excessive peeling of the layer
unsatisfactory
excessive peeling of the layer

unsatisfactory
excessive peeling of the layer

Coating according to US Pat. No. 29 46 683 and then with a coating of a photosensitive Coated diazo compound, which is a condensation product of p-diazodiphenylamine and paraformaldehyde was. Then an aqueous solution of 0.1% saponin and 0.25% diresorcinol over the Cast planographic printing plate. After a contact time of 1 to 2 seconds, the excess solution of spun off the plate and dried it. Then you had a coating that was light curable and was impervious to moisture, as evidenced by it being even after 45 days of treatment remained in a satisfactory condition at 90% relative humidity and 32.5 ° C. The test was carried out as follows, accomplished:

The plate was removed from the high humidity environment, exposed through a transparent negative, treated with a common developing agent, coated with a protective varnish and on a Press mounted. Printing was canceled after 8000 prints. The last prints were still excellent, which proves the good performance of the plate.

Example 3

An aluminum offset plate of 25 × 38 cm and 0.13 mm thick was _{coated successively with the same coatings of K 2 ZrF 6} and the diazo compound as in Examples 1 and 2. Then an isopropanol solution of 0.1% saponin and 0.05% sodium 2,2'-dihydroxy-4,4'-dimethoxy-5-sulfobenzophenone was poured over the planographic printing plate. After a contact time of 1 to 2 seconds, the excess solution was thrown off the plate and this dried; The coating thus obtained was photo-curable and impervious to moisture, which was found that it remained in a satisfactory state even after 45 days of treatment at 90 ° C. relative humidity and 32.5 ° C. and its performance was similar to that in Example 2 described attempt was good.

Example 4

An aluminum offset plate measuring 25 x 38 cm and 0.13 mm was successively _{coated with the same coatings of K 2 ZrF 6} and the diazo compound as in Examples 1 and 2. Then a solution of 50% butyl acetate and 50% water with 0.1% saponin and 0.25% 2,2 ', 4,4'-tetrahydroxybenzophenone was poured over the planographic printing plate. After a contact time of 1 to 2 seconds, the excess solution was spun off the plate and this was dried.

The resulting coating was light-curable and impervious to moisture, as shown by this proved that even after 45 days of treatment at 90% relative humidity and about 32.5 ° C in remained satisfactory and its performance in the test described in Example 2 was good.

Example 5

An aluminum offset plate measuring 25 x 38 cm and 0.13 mm thick was successively _{coated with the same coatings of K 2 ZrF 6} and the diazo compound as in Examples 1 and 2. Then a solution of 0.1% saponin and 0.40% N-ethyl-5-sulfoanthranilic acid in 50% acetone and 50% water was poured over the planographic printing plate. After a contact time of 1 to 2 seconds, the excess solution was spun off the plate and this was dried.

The coating thus obtained was curable by light and impermeable to moisture, as evidenced by the fact that it remained even after 45 days at 90% relative humidity and 32.5 ⁰ C in a satisfactory condition and its performance was good in the test described in Example 2.

Example 6

An aluminum offset plate of 25 x 38 cm and 0.13 mm thick was successively _{coated with the same coatings of K 2 ZrF 6} and the photosensitive diazo compound as shown in Examples 1 and 2. A solution of 0.1% saponin and 0.15% 4,4-bis (4-hydroxypjienyl) pentanecarboxylic acid in 90% water and 10% ethanol was then prepared and poured over the planographic printing plate.

After a contact time of 1 to 2 seconds, the spun off excess solution from the plate and dry it.

The resulting coating was light-curable and impervious to moisture, as evidenced by it shows that it is in a satisfactory state even after 45 days at 90% relative humidity and 32.5 ° C remained and its performance on the test described in Example 2 was good.

Example 7

An aluminum offset plate measuring 25 x 38 cm and 0.13 mm thick was successively _{coated with the same coatings of K 2 ZrF 6} and the photosensitive diazo compound as in Examples 1 and 2. Then a methanol solution of 0.1% saponin and 0.30% 1-naphthol-3-sulfonamide was poured over the planographic printing plate. After a contact time of 1 to 2 seconds, the excess solution was spun off the plate and this was dried.

This gave a coating which was curable by light and impermeable to moisture, such as As a result, it is satisfactory even after 45 days at 90% relative humidity and at 32.5 ° C Condition remained and its performance in the test described in Example 2 was good.

Example 8

An aluminum offset plate 25 × 38 cm and 0.13 mm thick was coated _{with K 2 ZrF 6 as in Examples 1 and 2.} Separately, 5 parts by volume of a 2% strength aqueous solution of the condensation product of p-diazodiphenylamine and paraformaldehyde and 4 parts by volume of isopropyl alcohol containing 5 g of 2,2 ', 4,4'-tetrahydroxybenzophenone were mixed. To the mixture, 1 part of water was added and the plate was coated with it.

After the excess solvent was spun off and the plate was dried, a diazo addition compound was coated the surface that was light-curable and impermeable to moisture, as can be seen from it that they are satisfactory even after 45 days at 90% relative humidity and at 32.5 ° C Condition remained and its performance in the test described in Example 2 was good.

Claims (2)

Patent claims: 1. Process for making a moisture-proof, photosensitive planographic printing plate by coating the plate with a photosensitive Condensation product of diazodiphenylamine and formaldehyde, characterized in that that the condensation product at a pH below 7.5 with a solution treated, which is a hydroxybenzophenone, a bis (hydroxyphenyl) alkyl carboxylic acid. Resorcinol, diresorcinol, 1-naphthol-3-sulfonamide, disodium-2-naphthol-3,6-disulfonate or N-alkyl-5-suIfoanthranilic acid contains. 2. The method according to claim I, characterized in that the hydroxybenzophenone is used 2,2 ', 4,4'-tetrahydroxybenzophenone is used.