US3235383A

US3235383A - Reproduction material for the photomechanical preparation of planographic and offsetprinting plates

Info

Publication number: US3235383A
Application number: US269760A
Authority: US
Inventors: Steppan Hartmut; Rebenstock August; Neugebauer Wilhelm
Original assignee: Azoplate Corp
Current assignee: Azoplate Corp
Priority date: 1961-01-25
Filing date: 1963-04-01
Publication date: 1966-02-15
Anticipated expiration: 1983-02-15
Also published as: NL136718C; DK111474B; US3236646A; BE613045A; LU43477A1; NL273557A; DE1292001B; GB986683A; SE339407B; DE1447002A1; DE1447002C3; DK111658B; SE325778B; GB1028674A; DE1447001A1; LU43476A1; BE630564A; NL134368C; CH434975A; SE339406B

Description

United States Patent 3,235,383 REPRUDUCTION MATERIAL FOR THE PHOTO- MECHANICAL PREPARATION OF PLANO- GRAPHIC AND OFFSET PRINTING PLATES Hartmut Steppan, Wiesbaden-Dotzheim, and August Rebenstock and Wilhelm Neugebauer, Wiesbaden- Biebrich, Germany, assignors, by mesne assignments, to Azoplate 'Corporation, Murray Hill, NJ. No Drawing. Filed Apr. 1, 1963, Ser. No. 269,760 Claims priority, application Germany, Apr. 3, 1962, K 46,364 35 (Ilaims. (Cl. 96-33) Copending application Serial No. 167,910, filed January 22, 1962, relates to reproduction materials for the photomechanical preparation of printing plates, in particular planographio and offset printing plates, which comprise a support and a reproduction coating adherent thereto, which is made light-sensitive with one or more salts of diazo compounds, formed by acid condensation of diphenylamine-4diazonium salts with formaldehyde, and in which phosphoric acid ions or free phosphoric acid are contained in quantities such that, per equivalent Weight of diazonium groups present, there is at least 0.05 mole of phosphoric acid or a phosphoric acid residue bound to the diazonium groups. In the copending application, supra, as in the present case, phosphoric acid is understood as ortho-phosphoric acid and the acids derived therefrom by dehydration, such as pyrophosphoric acid, other polyphosphoric acids and metaphosphoric acid. In polyphosphoric acids containing more than one phosphorus atom in the molecule, one mole of the acid is understood as the quantity which contains one mole of phosphorus (P) in bound form.

Thus, the copending application, supra, discloses a reproduction material of the type described in which at least one condensation product, formed from formaldehyde in acid-catalyzed condensation with at least one diphenylamine-4-diazonium salt, is contained as a lightsensitive substance and in which excess phosphoric acid is present in the reproduction coating. In the copending application, supra, as well as in this application, excess phosphoric acid is a quantity of phosphoric acid per mole (equivalent weight) of diazonium groups exceeding 1.5 moles, phosphoric acid ions which may be bound in the form of phosphate residues in any diazonium phosphates present being also counted as phosphoric acid. Such phosphate residues are always to be considered as primary phosphoric acid ions. A reproduction material of this type exhibits good shelf life combined with good performance.

A reproduction material has now been found which diifers from that previously described since, instead of formaldehyde, another reactive carbonyl compound is used as a condensation partner, and this material is also possessed of good properties as well as good shelf life.

The copending application, supra, further discloses a reproduction material comprising a support and a reproduction coating adherent thereto in which are contained, as light-sensitive substances, diazo compounds formed by the acid condensation with formaldehyde of diphenylamine-4-diazonium salts that contain phosphoric acid ions or phosphoric acid in a quantity inadequate for stabilization purposes. It has now been found that such reproduction materials in which the light-sensitive diazo Patented Feb. 15, 1966 compounds are condensation products with reactive carbonyl compounds other than formaldehyde are in practice also of excellent quality. As light-sensitive diazo compounds condensed with reactive carbonyl compounds, these reproduction materials may contain in the reproduction coating neutral polyfunctional diazonium phosphates of the formula (ArN H PO in which Ar is a condensed diphenylamine unit, and, except for the primary phosphoric acid ions bound to the neutral diazonium phosphate, either does not contain any phosphoric acid, or not more than 0.5 mole per equivalent weight of diazonium groups present. In reproduction materials in the reproduction coatings of which the diazo compound condensed with the reactive carbonyl compound is not in the form of a phosphate, which materials have but inadequate stability in storage, phosphoric acid is contained in a quantity of at least 0.05 tol.5 moles per equivalent weight of diazonium groups present.

As reactive carbonyl compounds substituted and unsubstituted aldehydes and ketones such as aliphatic aldehydes and ketones, aromatic aldehydes and ketones, and also mixed aliphatic/ aromatic and heretrocyclic aldehydes and ketones may be used. The aldehydes or ketones may also contain ethylenic unsaturation. Preferably, aliphatic aldehydes and ketones which contain 2 to 11 carbon atoms to the molecule and those from the aromatic aldehyde and ketone and the aliphatic-aromatic ketone group with 7 to 16 carbon atoms in the molecule are employed. The following are exemplary: acetaldehyde, iso butyraldehyde, benzaldehyde, benzaldehyde-3- sulfonic acid, chloral, acetone, butanone, di-isobutyl ketone, acetophenone, benzophenone, benzil, pyroracemic acid, cinnamaldehyde, uaphthalene-l-aldehyde, phenanthreno-quinone sulfonic acid, pyridine-3-aldehyde, quinoline-4-aldehyde, and mixtures thereof.

It has also been found that the condensation products from these reactive carbonyl compounds and diphenylarnine-4-diazonium salts may be used in the form of double salts with metal salts. Reproduction material which in its performance characteristics is in many cases equal to that described in the copending application, supra, is obtained, using as supports paper or aluminum foils roughened by brushing, by the use as sensitizers of metal halide double salts, e.g., zinc chloride, cadmium chloride, cobalt chloride and tin chloride double salts, of diazo compounds obtained by the condensation of substituted or unsubstituted diphenylamine4-diazonium salts with reactive carbonyl compounds, if these double salts are incorporated together with phosphoric acid in the reproduction coating.

Substituents which may be linked to the phenyl nuclei of the diphenylamine-4-diazonium compounds are, e.g.: alkyl and alkoxy groups, particularly such having 1 to 6 carbon atoms, further halides and the following groups: Carboxyl, COOH Carboxylic ester, COOR (R=alkyl or aryl) Carbonamide, CONH Cyan, -CN Acyl, -COR (R=alkyl or aryl) Alkoxy sulfonyl, -SO R (R=alkyl) Aryloxy sulfonyl, SO -R (R=aryl) Acylamino, NHCOR (R=alkyl or aryl) Alkylamino, NHR and NR (R=alky1) Arylamino, -NHR and NR (R=aryl) Sulfo, SO H.

Examples of such substituents which may be linked to the phenyl nuclei of the diphenyldiazonium groups are: methyl, ethyl, propyl, butyl, isobutyl, methoxy, ethoxy, fluorine, chlorine, brom, iodine, ethoxy carbonyl, phenoxy carbonyl, acetyl, methoxy sulfonyl, ethoxy sulfonyl, acetamino, methylamino, ethylamino, dimethylamino, diethylamino, methylethylamino, phenylamino, benzylamino, methylbenzylamino, and ethylbenzylamino.

The diphenylamine-4-diazonium compounds may be reacted with the aldehyde or ketone in the form of their salts with a strong acid, e.g. as salts of sulfuric acid, hydrochloric acid, hydrobromic acid, nitric acid, phosphoric acid, alkylphosphonic acid or arylphosphonic acid, trifiuoroacetic acid, hydrofiuoboric acid, methanesulfonic acid, toluene sulfonic acid and other aliphatic or aromatic sulfonic acids, amidosulfonic acid, selenic acid, hexafluophosphoric acid or perchloric acid. Alternatively, the diazonium compounds may also be used in the form of their double salts with metal salts for the reaction with the carbonyl compounds.

It is of advantage, particularly if the reproduction coating is to be applied to brushed aluminum, for the metal halide double salts to be used in a form as free as possible of extraneous salts. In the preparation of the double salts, it is thus better to dispense with the usual salting out and washing of precipitates with sodium chloride solution. The absence of extraneous metal salts, is however, not a prerequisite for the employment of such double salts in the reproduction material.

The concentration of the solution with which the supports of the reproduction materials are to be coated and which contains the light-sensitive diazo compound, depends upon the coating conditions and upon the nature of the supporting material and is limited, for example, by the solubility of the diazonium salt in the solvent used. The metal salt double salts which exhibit the best solubility in water or in mixtures of water with organic solvents are the double salts of polyfunctional diazonium salts with cobalt chloride or zinc chloride, and therefore the use of these salts is preferred.

On brushed aluminum foils as supports, good results are obtained if the concentration of the diazo compound in the coating solution is in the range of about 0.01 to 2 percent by weight. Concentrations of 0.05 to 0.5 percent by weight are preferred. On a paper support, such as that described in US. Patent No. 2,778,735, solutions of higher concentration are preferred, i.e., from about 0.1 to percent by weight of diazo compound, preferably 0.2 to 5 percent by weight.

The paper support described in the U.S. patent consists of a coated paper having a calendered coating layer thereon which coating consists essentially of an unsolubilized carboxymethylhydroxyethyl cellulose adhesive in which the ratio of carboxymethyl groups to hydroxyethyl groups is within the range from 0.3 to 1 and in which the degree of substitution of the anhydroglucose units is greater than 0.8 and a greater quantity of a non-hydrous pigment, viz. blanc fixe and/or titanium dioxide.

The quantity of phosphoric acid used in the preparation of the reproduction coating is determined by the purpose for which the material is intended and depends, among other things, upon the type of supporting material employed and upon the concentration of the coating solution,

For example, with brushed aluminum foils as supporting materials and a concentration of 0.1 percent by weight of diazo compound in the coating solution, the content of free phosphoric acid usually will be maintained between about 0.01 and 6 moles, preferably in the range of about 0.1 to 4 moles per equivalent weight of diazo groups present.

Using a paper support of the type described in US. Patent No. 2,778,735, a higher content of phosphoric acid is preferred, e.g., with a coating solution concentration of 1 percent by weight, generally 3 to 100 moles, preferably 7 to 50 moles, per equivalent weight of diazonium groups present. In this case, some of the phosphoric acid can be replaced by another acid of low volatility, e.g., sulfuric acid or arsenic acid.

For the preparation of printing plates from the reproduction material of the invention, the process is as described in the copending application, supra, if supports of the type described in US. Patent No. 2,778,735, are used, i.e., after the reproduction material has been exposed, the reproduction coating is wiped over with water or aqueous solutions of gum arabic, which may contain organic solvents, and is then inked up with printing ink, either by rubbing with a swab by hand or in a printing machine. The printing ink may also be rubbed in even before development. If a brushed aluminum foil is used as a support, it is of advantage, if the plate is to be developed by a Wiping over process, for the exposed plate to be first wiped over with water-miscible organic solvents, e.g., glycol, glycerine, glycol-monomethyl ether, polyglycol or dimethyl formamide, and for the printing ink to be applied afterwards. The printing plate can also be wiped over after exposure with one of the aforementioned solvents and then treated with an emulsion lacquer, for example one such as is described in US. Patent No. 2,754,279, and then treated with water and inked up. The exposed plate may also be developed immediately with the aforementioned lacquer, then wiped over with water, and inked up. With printing images reinforced in this way, a particularly high number of flawless prints can be obtained. The plate may however be put on the printing machine immediately after exposure and inking and wetting begun. Even with this process, a large number of flawless prints can be produced with the printing foil. If printing is not begun immediately after the planographic plate has been prepared, gumming is advisable.

In the following examples one part by volume corresponds to 1 ml. when one part by weight is taken as 1 g.

Example 1 A brushed aluminum foil is coated, for example on a whirler, with a solution containing 0.2 part by weight of a condensation product precipitated in the form of a chloride, the preparation which is described below, and 0.145 part by weight of 85 percent phosphoric acid dissolved in a mixture of 8 parts by volume of water, parts by volume of glycol monomethyl ether and 37 parts by volume of dimethyl formamide. The reproduction material is dried for 2 minutes at 100 C.

A presensitized printing plate is obtained which can be stored for an extended period without losing its good properties as a printing plate.

For the preparation of the diazo compound, 30.3 parts by weight of diphenylamine-4-diazonium sulfate (96.4 percent solution in water), were introduced into 100 parts by weight of 90 percent sulfuric acid; 6.4 parts by weight of acetone were then introduced dropwise into the mixture at a temperature of 20 C. After standing for 24 hours at room temperature, 20 parts by Weight of the crude condensate were dissolved in 35 parts by volume of a water-methanol mixture (1:1) and then treated with 14.6 parts by volume of l-molar hydrochloric acid. After a: small quantity of undissolved material had been filtered otf, the solution was diluted with 250 parts by volume of methanol and the diluted solution was treated with calcium carbonate until the solution had a pH of 6 to 6.5.v The solution, after separation of calcium salts, was evaporated to dryness in vacuo at temperatures not exceeding 50 C. to yield the chloride of the condensation product.

For the preparation of a printing plate, the reproduction layer is exposed under a negative for 30 to seconds to an 18-amp arc lamp at a distance of cm. and a positive printing plate is obtained by development with an emulsion lacquer as described, for example, in US. Patent No. 2,754,229. From this printing plate, long runs of prints can be obtained.

Example 2 The procedure described in Example 1 is followed but for the coating mix a solution is used which contains 0.17 part by weight of the condensation product precipitated as described below in the form of a chloride and 0.145 part by weight of 85 percent phosphoric acid in a mixture of 8 parts by volume of water, 55 parts by volume of glycol monomethyl ether and 37 parts by volume of dimethly formamide. The coating is dried for 2 minutes at 100 C.

For the preparation of the diazonium salt, 30.3 parts by weight of diphenylamine-4-diazonium sulfate (96.4 percent) are introduced into 100 parts by weight of 80 percent sulfuric acid. 9.7 parts by weight of pyroracemic acid are then added in fractions. The mixture is stirred for 2 hours at 40 C. and then allowed to stand for 12 hours at room temperature. 40 parts by weight of the resulting crude condensate, with an addition of 150 parts by volume of methanol, are then treated with saturated barium chloride solution until there is neither an excess of barium nor sulfate ions. For the isolation of the thawnium chloride, the solution is separated from the barium sulfate and evaporated in vacuo to dryness.

For the preparation of a printing foil from the resulting reproduction material, exposure is performed as described in Example 1 and conversion into a high-output printing plate is effected by wiping over with ethylene glycol and subsequent reinforcement of the image with the emulsion lacquer described in Example 4 of U8. Patent No. 2,754,279.

Example 3 A paper support, the preparation of which is described in U.S. Patent No. 2,778,735, is coated with a solution containing 1.5 parts by weight of a condensation product described in detail below and 8 parts by weight of 85 percent phosphoric acid in 100 ml. of water.

For the preparation of the diazo compound, 25.9 parts by weight of diphenylamine-4-diazonium chloride are introduced at room temperature into a mixture of 4.8 parts by weight of paraldehyde and 50 parts by volume of 63 percent hydrobromic acid. After standing overnight at room temperature, the mixture is dissolved in a mixture of 400 parts by volume of isopropanol and 600 parts by volume of water and the condensation product is precipitated by the addition of 100 parts by volume of 50 percent zinc chloride solution. The precipitate is filtered ofl? with suction, washed with aqueous isopropanol, and dried.

The reproduction material thus obtained can be exposed under a master for about 2 minutes, following the procedure of Example 1, and developed by wiping over with water, after which it can be inked up with greasy ink.

Example 4 A paper support is coated as described in Example 1, but the coating solution applied contains 1 part by weight of a condensed sulfate, described below, together with 6 parts by weight of 85 percent phosphoric acid in 100 parts by volume of water.

For the preparation of the condensation product, 3.2 parts by weight of quinoline-4-aldehyde are introduced into 21.8 parts by weight of 90 percent sulfuric acid and then 5.9 parts by weight of diphenylamine-4-diazonium sulfate are introduced into the mixture. After condensation for 12 hours at room temperature, the reaction mixture is diluted with 25 parts by volume of methanol and then poured, as a thin stream, into 100 parts by volume of isopropanol while vigorously stirring. The condensed sulfate which precipitates is filtered off and dried.

If stored in the dark, a paper thus coated maintains its light sensitivity for many months. For developing the exposed paper printing foil, it may be inked up with greasy ink and then wiped over with water.

Example 5 An aluminum foil roughened by brushing is coated with a solution which contains 0.13 part by weight of the chloride of a condensation product described below in combination with 0.11 part by weight of 85 percent phosphoric acid, dissolved in a mixture consisting of 8 parts by volume of water, 55 parts by volume of ethyleneglycol monomethylether, and 37 parts by volume of dimethylformamide.

For the preparation of the diazo compound, 61.1 parts by weight of diphenylamine-4-diazonium sulfate and 22 parts by weight of benzaldehyde are introduced, with stirring, into 121.5 parts by volume of 96 percent sulfuric acid and the resulting mixture is condensed for 48 hours at room temperature. For removal of the greater part of the sulfuric acid, the mixture is poured into isopropanol, while agitating, and the resulting precipitate is isolated. Conversion into the chloride is eifected by dissolving the precipitate in aqueous methanol, precipitating sulfuric acid and sulfate ions by the addition of barium chloride solution, and completely evaporating the filtrate, which is free of sulfate and barium ions.

When stored in the dark, the coated metal foil maintains its light sensitivity over a period of many months. When the foil is to be used, it is advantageously converted into a printing plate by exposure under a master, wiping over with ethylene glycol, and subsequent treatment with an emulsion lacquer.

Example 6 The procedure described in Example 5 is repeated, but a coating solution is used which contains 0.31 part by Weight of the zinc chloride double salt of the condensation product described below and 0.2 part by weight of 85 percent phosphoric acid in a mixture of 8 parts by volume of water, 55 parts by volume of ethyleneglycol monomethylether, and 37 parts by volume of dimethyl formamide.

For the preparation of the diazo compound, 32 parts by weight of 3-methoxy-diphenylamine-4-diazonium sulfate and 11.6 parts by weight of benzaldehyde are introduced into 100 parts by Weight of percent sulfuric acid. The mixture is heated briefly to 40 C. and then left standing overnight at room temperature. Separation of the zinc chloride double salt is effected in known manner.

When stored in the dark, the light sensitivity of the printing foil remains good for a period of many months. A printing plate may be prepared, e.g. by exposing the plate under a master and then treating it first with ethyleneglycol monomethylether and then with an emulsion lacquer.

Example 7 An aluminum foil roughened by brushing is coated with a solution which contains 0.16 part by weight of the cobalt chloride double salt of the condensation product described below and 0.14 part by weight of percent phosphoric acid in a mixture of 8 parts by volume of water, 55 parts by volume of ethyleneglycol monomethylether and 37 parts by volume of dimethylformamide.

For the preparation of the condensation product, 30.3 parts by weight of diphenylamine-4-diazonium sulfate (96 percent) and 14.5 parts by weight of cinnamaldehyde are introduced into 54 parts by volume of 96 precent sulfuric acid. The mixture is condensed for 1 hour at 40 C. and subsequently the sulfate of the condensation product is separated in accordance with the procedure of Example 4. For conversion into the cobalt chloride double salt, 4 parts by weight of the sulfate are dissolved in a mixture of 40 parts by volume of 36 percent sulfuric acid and 100 parts by volume of isopropanol, 2.5 parts by weight of CoCl -6H O dissolved in parts by volume of isopropanol are added to the mixture, and the precipitating double salt is filtered off and dried.

The printing plate thus obtained can be stored for many months. The conversion into a printing plate is as described in Example 5.

It will be obvious to those skilled in the art that many modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications.

What is claimed is:

1. A presensitized printing plate comprising a base material having a coating thereon comprising at least one polyfunctional condensation product of a diphenylamine- 4-diazonium salt with a reactive carbonyl compound having at least two carbon atoms, and at least 0.05 mole of phosphoric acid of the group consisting of orthophosphoric, metaphosphoric, pyrophosphoric acid and polyphosphoric acids and taken as the sum of free phosphoric acid and phosphoric acid bound to the diazonium groups, per mole of diazonium groups.

2. A presensitized printing plate according to claim 1 in which in excess of 1.5 moles of phosphoric acid, including that bound to diazonium groups, are present per equivalent weight of diazonium groups.

3. A presensitized printing plate according to claim 1 in which the diazonium salt is a neutral phosphate and not in excess of 0.5 mole of free phosphoric acid is present per equivalent weight of diazonium groups.

4. A presensitized printing plate according to claim 1 in which the phosphoric acid is present in a quantity in the range of about 0.05 to 100 moles per equivalent weight of diazonium groups.

5. A presensitized printing plate according to claim 1 in which the base material is paper and the phosphoric acid is present in a quantity in the range of about 1.5 to 100 moles per equivalent weight of diazonium groups.

6. A presensitized printing plate according to claim 1 in which the base material is aluminum and the phosphoric acid is present in a quantity in the range of about 1.5 to 5 moles per equivalent weight of diazonium groups.

7. A presensitized printing plate according to claim 1 in which the condensation product is metal salt-free.

8. A presensitized printing plate according to claim 1 in which the condensation product contains metal salt.

9. A presensitized printing plate according to claim 1 in which the condensation product is present, at least partially, in the form of a double salt with a metal salt.

10. A presensitized printing plate according to claim 1 in which the condensation product is of diphenylamine-4- diazonium sulfate and acetone.

11. A presensitized printing plate according to claim 1 in which the condensation product is of diphenylamine- 4-diazonium sulfate and pyroracemic acid.

12. A presensitized printing plate according to claim 1 in which the condensation product is of diphenylamine- 4-diazonium chloride and paraldehyde.

13. A presensitized printing plate according to claim 1 in which the condensation product is of diphenylamine- 4-diazonium sulfate and quinoline-4-aldehyde.

14. A presensitized printing plate according to claim 1 in which the condensation product is of diphenylamine- 4-diazonium sulfate and benzaldehyde.

15. A presensitized printing plate according to claim 1 in which the condensation product is of S-methoxydiphenylamine-4-diazonium sulfate and benzaldehyde in the form of the zinc chloride double salt.

16. A presensitized printing plate according to claim 1 in which the condensation product is of diphenylamine- 4-diazonium sulfate and cinnamaldehyde in the form of the cobalt chloride double salt.

17. A process for making a printing plate which comprises exposing a supported sensitized layer to light under a master and developing the resulting image, the sensitized layer comprising at least one polyfunctional condensation product of a diphenylamine-4-diazonium salt with a reactive carbonyl compound having at least two carbon atoms, and at least 0.05 mole of phosphoric acid of the group consisting of orthophosphoric, metaphosphoric, pyrophosphoric acid and polyphosphoric acids and taken as the sum of free phosphoric acid and phosphoric acid bound to the diazonium groups, per mole of diazonium groups.

18. A process according to claim 17 in which in excess of 1.5 moles of phosphoric acid are present per equivalent weight of diazonium groups.

19. A process according to claim 17 in which the diazonium salt is a neutral phosphate and not in excess of 0.5 mole of free phosphoric acid is present per equivalent weight of diazonium groups.

20. A process according to claim 17 in which the phosphoric acid is present in a quantity in the range of about 0.05 to moles per equivalent weight of diazonium groups.

21. A process according to claim 17 in which the base material is paper and the phosphoric acid is present in a quantity in the range of about 1.5 to 100 moles per equivalent weight of diazonium groups. sulfate and quinoline-4-aldehyde. material is aluminum and the phosphoric acid, including that bound to diazonium groups, is present in a quantity in the range of about 1.5 to 5 moles per equivalent weight of diazonium groups.

23. A process according to claim 17 in which the condensation product is metal salt-free.

24. A process according to claim 17 in which the condensation product contains metal salt.

25. A process according to claim 17 in which the condensation product is present, at least partially, in the form of a double salt with a metal salt.

26. A process according to claim 17 in which the condensation product is of diphenylamine-4-diazonium sulfate and acetone.

27. A process according to claim 17 in which the condensation product is of diphenylamine-4-diazonium sulfate and pyroracemic acid.

23. A process according to claim 17 in which the condensation product is of diphenylamine-4-diazonium chloride and paraldehyde.

29. A process according to claim 17 in which the condensation product is of diphenylamine-4-diazonium sulfate and quinoline-4-aldehyde.

30. A process according to claim 17 in which the condensation product is of diphenylamine-4-diazonium sulfate and benzaldehyde.

31. A process according to claim 17 in which the condensation product is of 3-methoxy-diphenylamine-4- diazonium sulfate and benzaldehyde in the form of the zinc chloride double salt.

32. A process according to claim 17 in which the condensation product is of diphenylamine-4-diazonium sulfate and cinnamaldehyde in the form of the cobalt chloride double salt.

33. A presensitized printing plate according to claim 1 in which at least one of the phenyl nuclei of the salt carries a substituent of the group consisting of alkyl, alkoxy, halide, carboxy, carboxylic esters, carbonamide, cyan, acyl, alkoxy sulfonyl, aryloxy sulfony l, acylamino, alkylamino, arylamino, sulfo.

34. A coating solution for making a printing plate, comprising a solvent and dissolved therein (a) a condensation product of a diazonium salt selected from the group consisting of diphenylamine-4-diazonium salt and diphenylamine-4-diazonium sa'lts carrying at at least one of their phenyl nuclei a substituent selected from the group consisting of alkyl, alkoxy, halide, carboxy, carboxylic ester, carbonamide, cyan, acyl, alkoxy sulfonyl, aryloxy sulfonyl, acylamino, and alkylamino, arylamino, sulfo, with a reactive carbonyl compound having at least two carbon atoms and (b) at least 0.05' mole of phosphoric acid of the group consisting of orthophosphoric, metaphosphoric, pyrophosphoric acid and polyphosphoric acids and taken as the sum of free phosphoric acid and 9 phosphoric acid bound to the diazonium groups, per mole of diazonium groups.

35. The coating solution of claim 34 comprising at least 1.5 moles of said phosphoric acid per mole of diazoniurn groups.

References Cited by the Examiner UNITED STATES PATENTS 10 2,679,498 5/1954 Seven et a1. 9633 X 2,937,085 5/1960 Seven et a1. 9675 X FOREIGN PATENTS 698,040 10/1953 Great Britain.

OTHER REFERENCES Der'went: Belgian Patents Report, No. 92A, Oct. 12, 1962, page 16 of Section 3, abstract of No. 613,045.

2,063,631 12/ 1936 Schmidt et a1. 9691 X 10 NORMAN G. TORCHIN, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 235,383 February 15, 1966 Hartmut Steppan et al 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 4, line 43, after "preparation" insert of column 8 line 20, strike out "sulfate and quinoline-4- aldehyde." and insert as the beginning of a new paragraph,

- 22 A process according to claim 17 in which the base Signed and sealed this 17th day of January 1967 Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesu'ng Officer Commissioner of Patents

Claims

1. A PRESENSITIZED PRINTING PLATE COMPRISING A BASE MATERIAL HAVING A COATING THEREON COMPRISING AT LEAST ONE POLYFUNCTIONAL CONDENSATION PRODUCT OF A DIPHENYLAMINE4-DIAZONIUM SALT WITH A REACTIVE CARBONYL COMPOUND HAVING AT LEAST TWO CARBON ATOMS, AND AT LEAST 0.05 MOLE OF PHOSPHORIC ACID OF THE GROUP CONSISTING OF ORTHOPHOSPHORIC, METAPHOSPHORIC, PYROPHOSPHORIC ACID AND POLYPHOSPHORIC ACIDS AND TAKEN AS THE SUM OF FREE PHOSPHORIC ACID AND PHOSPHORIC ACID BOUND TO THE DIAZONIUM GROUPS, PER MOLE OF DIAZONIIUM GROUPS.

17. A PROCESS FOR MAKING A PRINTING PLATE WHICH COMPRISES EXPOSING A SUPPORTED SENSITIZED LAYER TO LIGHT UNDER A MASTER AND DEVELOPING THE RESULTING IMAGE, THE SENSITIZED LAYER COMPRISING AT LEAST ONE POLYFUNCTIONAL CONDENSATION PRODUCT OF A DIPHENYLAMINE-4-DIAZONIUM SALT WITH A REACTIVE CARBONYL COMPOUND HAVING AT LEAST TWO CARBON ATOMS, AND AT LEAST 0.05 MOLE OF PHOSPHORIC ACID OF THE GROUP CONSISTING OF ORTHOPHOSPHORIC, METAPHOSPHORIC, PYROPHOSPHORIC ACID AND POLYPHOSPHORIC ACIDS AND TAKEN AS THE SUM OF FREE PHOSPHORIC ACID AND PHOS PHORIC ACID BOUND TO THE DIAZONIUM GROUPS, PER MOLE OF DIAZONIUM GROUPS.