US3220832A - Presensitised planographic printing plates and methods of preparing and using such - Google Patents

Description

aired States Patent 3,220,832 PRESENSITISEEB PLANOGRAPHIC PRINTING PLATES AND METHODS OF PREPARING AND UdiNG SUCH Fritz Uhiig, Wiesbaden-Biebrich, Germany, assignor, by mesne assignments, to Azoplate Corporation, Murray Hiil, N].

No Drawing. Filed July 18, 1961, Ser. No. 124,804 Claims priority, application Germany, Aug. 5, 1960, K 41,387; Feb. 25, 1961, K 43,011 38 Claims. (Cl. 96-4) This invention relates to plates for planographic printing, wherein aluminum is used as a supporting material for the reproduction coating and is provided with a thin coating consisting of one or more phosphonic acids and/ or derivatives thereof.

Aluminum that is to be used as supporting material for the preparation of planographic printing plates requires a preliminary treatment to enable the reproduction coating to adhere well. Virgin aluminum sheet has been processed mechanically, by means of graining machines, or steel or plastic brushes, to give a suitable supporting material. Light-sensitive coatings do not, however, adhere to material treated in this way to the extent that is desirable, if very long printing runs are to be obtained. The aluminum surface has also been first cleaned with alkaline agents, possibly then etched with nitric acid, and finally silicated by treatment with aqueous alkali silicate solutions. Aluminum treated in this way has the disadvantage that only a very few types of light-sensitive coatings, all negative-working, adhere thereto.

Aluminum has also been treated electrolytically for reproduction purposes. This process is, however, very troublesome, particularly with regard to current supply in the case of the processing of a continuous band of material, and Where wide bands of aluminum are being treated.

Planographic printing plates comprising an aluminum support and a reproduction coating adherent thereto have now been found in which there is a thin intermediate layer between the aluminum support and the reproduction coating, the thin intermediate layer consisting wholly or in part of at least one phosphonic acid and/ or derivative thereof.

For the preparation of the planographic printing plates of the invention, aluminum plates which have a phosphonic acid coating are coated with a reproduction coating, preferably dissolved in a solvent, by known methods, e.g., immersion, roller application, application to the support while rotating, and the like. The solvent is then removed and aluminum supports covered with an even, homogeneous coating are thereby obtained which can be converted by known methods into plates ready for printing.

The phosphonic acid coating is produced on ordinary commercial grade aluminum, particularly in the form of plates or, with continuous processing, in the form of continuous bands, in accordance with known methods for the production of coatings. The aluminum may be subjected, before the phosphonization process, to one of the known cleaning processes, e.g., in hot alkali phosphate or carbonate solution, in oxidizing agents such as dilute nitric acid, or in nitrate, chromate or hydrogen peroxide soluice tions. The aluminum may also be cleaned by the aid of electric current, either cathodically or anodically.

The aluminum can then be immersed in cold or hot solutions of phosphonic acids, or derivatives or substitution products thereof, in water or in inorganic or organic solvents. A phosphonic acid coating may also be formed by roller application or by the application of phosphonic acid solutions to the supporting material while rotating.

The phosphonic acids used in the present invention include organic phosphonic acids and derivatives thereof in the broadest possible sense, including aromatic, substituted aromatic, substituted and non-substituted saturated and unsaturated cyclic, aliphatic, heterocyclic phosphoric acids and also polymers and interpolymers of unsaturated phosphonic acids with each other or with other vinyl compounds, as well as derivatives thereof, such as salts or esters.

The following may be mentioned by way of example: vinyl phosphonic acid, polyvinyl phosphonic acid, 2-phosphono-ethane-l-sulfonic acid, vinyl phosphonic acid monomethyl ester, vinyl phosphonic acid ethyl ester, 4- chlorophenyl phosphonic acid, 4-chloro-3-nitrophenyl phosphonic acid, S-nitronaphthalene phosphonic acid, B-styryl phosphonic acid and interpolymers of vinyl phosphonic acid with acrylic acid and vinyl acetate or mixtures thereof and their salts. Depending upon the nature of the aluminum surface, the temperature employed and the concentration of the phosphonic acid solution, the treatment requires from a few seconds to several minutes. In general, treatments of 5 seconds to 10 minutes, preferably 60 seconds to 2 minutes, at temperatures of 20100 C. with about 0.001 to 10% (preferably 0.01-3%) solutions of phosphonic acids are adequate. The treatment may be further prolonged and either higher or lower concentrations may be used if desired. However, conditions outside the range mentioned may often either be less favorable or not produce any improvement in results. If the aluminum plates are immersed in a bath, the bath may contain 0.1% phosphonic acid solutions in water or organic solvents, for example; if the coating is to be applied to the support, while rotating, 0.011% phosphonic acid solutions in organic solvents such as methyl ethyl ketone, toluene, butyl acetate, ethylene glycol monomethyl ether or dimtehyl formamide or mixtures thereof are preferably used.

Suitable compounds to improve the hydrophilic properties of the aluminum surface, such as hydrophilic colloids, e.g., cellulose others such as carboxymethyl cellulose, hydroxyethyl cellulose and methyl cellulose or alginates, may be added to the phosphonic acid solutions.

The resultant phosphonic acid coating may be briefly rinsed with water and then dried. Drying at fairly high temperatures has an advantageous effect on the adhesion of the coatings. Solutions of the organic reproduction coatings can then be coated by hand or by means of suitable coating machines.

The materials used for the reproduction coatings for the plangrophic printing plates of the present invention are, in general, any with which, as a result of the action of visible, ultra-violet or infra-red light or X-rays or heated objects, image-wise differentiation is possible, e.g., light-sensitive organic compounds such as aliphatic and aromatic esters, hydrazides and amides of naphthoquinone-diazide sulfonic acids, cinnamal malonic acid, its substitution products andfunctional derivatives, diazonium salts of amino-diphenylamine and condensation products thereof with formaldehyde, ortho and para-quinone diazides of benzene, anthracene and heterocyclic systems, e.g., of quinoline, indazole, benzimidazole, fluorene and diphenylene oxide, also diazo ketones, unsaturated ketones, ortho and para-iminoquinone diazides, derivatives of alkyl-nitronaphthalene sulfonic acids, nitroaldehydes, acenaphthenes, nitrous, stilbenes, azides and diazides and higher-polymeric diazo compounds.

A particularly suitable light-sensitive substance is a condensation product free of metal salts and obtained by acid condenation of a diphenylamine-4-diazonium salt with formaldehyde. When a light-sensitive substance of this kind is employed, the copying material is highly light sensitive, has very good shelf-life and is very resistant to rubbing.

Example of suitable polyfunctional diazonium salt free of metal salt are those obtained by condensation of the diazonium salt, e.g. diphenylamine-4-diazonium chloride, diphenylamine-4-diazonium bromide or diphenylamine-4- diazonium phosphate, with formaldehyde in strong phosphoric acid or polyphosphoric acid. The crude condensate may be diluted and then applied direct to aluminium which has been pretreated with a phosphoric acid and dried. However, after the completion of condensation, the phosphoric acid may be separated from the reaction mixture in the form of a feebly soluble salt by treatment with a suitable metal carbonate, bicarbonate or hydroxide, and the readily soluble neutral halide of the condensation product may be isolated in solid form by evaporation. It is not essential for phosphoric acid to be used as condensation agent; the condensation product can also be obtained by condensation of an unsubstituted or substituted diphenylamine-4-diazonium halide with formaldehyde in hydrofluoric acid, hydrochloric acid or hydrobromic acid and recovering the condensation product by evaporation in vacuo.

Also, reproduction coatings can be applied which have a high electrical resistance in the absence of light but which decreases by several powers of ten under the influence of light or heat, such as are used in electrophotography and electrothermography, e.g., organic photoconductors of lower or high molecular weight, if desired in association with resins. Photoconductors that have proved particularly suitable are oxadiazoles, imidazolones, triazoles, oxazoles, thiazoles, hydrazones, triazines, polyvinyl carbazole and polyvinyl oxazoles.

As the resins, those which are suitable have groups conferring alkali-solubility such as acid anhydride, carboxylic acid, sulfonic acid, sulfonamide or sulfonimide groups e.g., vinyl polymers and vinyl interpolymers, phthalic acid ester resins, maleinate resins, alkyd resins, colophony resins and polyacrylic acid resins.

The planographic printing plates of the invention have the advantage that practically all known types of reproduction coatings adhere excellently to the phosphonic acid surface and, moreover, after the usual image-wise exposure and removal of the coating in the image-free parts (which may be eflfected with water, weak alkalis or acids, according to the type of reproduction coating used), they give long printing runs in the machines normally used for offset printing, sometimes several times the length of those obtained with grained aluminum foils such as have hitherto been used. The planographic printing plates have the further advantage that they are very easy to prepare, as ordinary rolled aluminum sheet can generally be passed immediately to a bath and subjected to the phosphonic acid treatment.

The invention will be further illustrated by reference to the following specific examples:

Example I A mechanically roughened aluminum foil is immersed for 60 seconds at C. in a bath of 0.01% polyvinyl phosphonic acid in solution in pure water. After being dried, it is coated with a 1% aqueous solution of the zinc chloride double salt of a diazo compound prepared by condensation in sulfuric acid of 1 mole of 4-diazodiphenylamine and 1 mole of formaldehyde. After exposure under a master, the diazo compound is dissolved away, in the parts not affected by the light, by rinsing with water and the image parts are inked up with greasy ink. Printing can then be performed in the usual way. This diazo compound does not adhere satisfactorily to mechanically roughened aluminum surface that has not had a preliminary phosphonic acid treatment.

Example I! A thin band of virgin aluminum sheet is drawn through a bath containing a hot C.) solution of 0.1% vinyl phosphonic acid and 0.01% carboxymethyl cellulose in Water. It is then dried, coated with a 2% solution of l-(4-methylbenzene-l-sulfonyl) imino 2 (2,5"-dimethyl-phenylamino sulfonyl) benzoquinone (1,4)- diazide-(4) in ethylene glycol monomethyl ether in known manner, dried again and cut into suitable sheets.

For the preparation of a printing plate, the coated side of the foil is exposed under a film master and the exposed coating is treated with a cotton pad that has been soaked in 3% trisodium phosphate solution. In the parts affected by the light, a yellow image of the master is left adhering. After it has been rinsed down with water, it is inked up with greasy ink and can be used for printing in a conventional machine.

This diazo compound does not adhere satisfactorily to virgin aluminum plate that has not had a preliminary phosphonic acid treatment.

Example III An aluminum foil is coated on a rotating whirler with a 1% solution of S-nitronaphthalene phosphonic acid in ethylene glycol monomethyl ether, dried and then coated, by the method described above with a 1.5% solution of 4-diazodiphenylamine chloride and dried.

After exposure under a master, an image that is negative in relation to the master is obtained if the parts unaffected by the light are dissolved away with water. After the plate has been inked up with greasy ink it can be used for printing. In the image parts the coating is resistant to rubbing with 20% phosphoric acid while on aluminum that has not been given a preliminary treatment with phosphonic acids this diazo compound has only poor .adhesive properties. Z-phosphonoethane-l-sulfonic acid, vinyl phosponic acid monomethyl ester or vinyl phosphonic acid monoethyl ester can be used with equal success instead of 5-nitro-naphthalene-phosphonic acid.

Example IV On a rotating whirler, an aluminum foil is coated with a solution of 0.05% vinyl phosphonic acid and 0.05% polyvinyl phosphonic acid in ethylene glycol monoethyl ether, dried, coated by the method described above with a 1.5% solution of the naphthoquinone-(1,2)-diazide-(2)- S-sulfonic acid ester of 2,3,4-trihydroxybenzophenone in ethylene glycol monoethyl ether and dried with hot air.

After exposure with a diapositive, an image which is positive with respect to the master is obtained if the coating is dissolved away, in the parts affected by the light, by wiping over with a cotton pad that has been soaked in 3% trisodium phosphate solution. The plate is rinsed with water and phosphoric acid of about 1% concentration and the image parts are inked up with greasy ink.

Example V A mechanically roughened aluminum foil is immersed for 5 minutes at 70 C. in a 20% aqueous solution of trisodium phosphate and then for 60 seconds at 20 C. in a bath of 0.1% aqueous polyvinyl phosphonic acid. After this layer has been dried, it is coated with a solution, in ethylene glycol monomethyl ether, of 0.3% of-2-phenylimino 3 hydroxyethyl-5-cinnamylidene-thiazolidon-(4), 0.3% of di-cinnamylidene acetone and 0.3% of a phenol resin modified by reaction with chloroacetic acid. After exposure under a photographic negative, the light-sensitive coating is hardened in the parts affected by the light and dissolved away in the parts not atfected by the light by wiping over with a solution of 50 parts by weight of sodium metasilicate in 700 parts by volume of water, 500 parts by weight of triethylene glycol and 200 parts by weight of glycerine. The image parts are then inked up with greasy ink.

Example VI 1 part by weight of 2,5-bis-[4-diethylaminophenyl- (1)]-1,3,4-oxadiazole, 0.8 part by weight of a styrene interpolymer, containing carboxyl groups and having a specific gravity of 1.26-1.28 and a decomposition temperature ranging from 200 to 240 C., and 0.003 part by weight of Rhodamine B extra (Schultz, Farbstofrtabellen, 7th edition, vol. 1, No. 864) are dissolved in 30 parts by volume of ethylene glycol monomethyl ether. The solution is coated upon an aluminum foil which has been treated for the production of a phosphonic acid coating, as described in Example I, and then dried. For the production of images on the electrocopying material thus prepared, the coating is charged by means of a corona discharge and then exposed under a master for one second to a l25-watt mercury lamp. The resultant electrostatic image of the master is made visible by dusting over with a resin powder pigmented with carbon black and fixed as an irremoveable electrocopy by heating to 150 C. For the preparation of a printing plate, the electrocopy is wiped over with a solution consisting of 30 parts by volume of methanol, 20 parts by volume of glycerine and 35 parts by volume of ethylene glycol monomethylether. The plate is then briefiy rinsed with water and treated with dilute (about 0.5 to 5%) aqueous phosphoric acid solution. After the resulting printing plate has been inked up with greasy ink, it can be used for printing in the usual manner in an offset machine, direct images corresponding to the master being obtained.

Example VII A mechanically roughened aluminum foil is immersed for 60 seconds at 30 C. in a solution in water of 0.8% of polyvinyl phosphonic acid and 0.2% of vinyl phosphonic acid. After the aluminum foil has been rinsed with water and dried, the foil is coated with a light sensitive solution containing 0.5 part by weight of a crude condensate of paraformaldehyde and diphenylamine-4-diazonium chloride described in detail below, 8 parts by weight of water, 80 parts by weight of glycol monomethyl ether and 20 parts by weight of dimethyl formamide. The coated aluminum foil is dried and heated for a further two minutes to 100 C. The light sensitive coating, which has very good keeping qualities in the unexposed state, is exposed with a photographic negative, e.g., for 40 seconds to an lS-amp arc lamp at a distance of 70 cm. The exposed coating is developed with an aqueous solution containing 8% of gum arabic by means of a pad and is then inked up with greasy ink. The plate is then ready for printing. The image on the printing plate may also be strengthened with lacquer in known manner. Alternatively development and lacquering can be effected simultaneously by means of an aqueous emulsion lacquer. The resulting printing plate is extraordinarily resistant to rubbing with phosphoric acid and with the phosphoric acid anti-scumming agents commonly used in printing machines.

The support used can also be an aluminum foil covered with a layer of Bohmit, an electrolytically roughened aluminum foil or a foil of virgin aluminum sheet. The results obtained are just as good as those obtained with the mechanically roughened aluminum foil.

The crude condensate from paraformaldehyde and diphenyl-4-diazonium chloride is prepared as follows:

3.3 parts by weight of paraformaldehyde and 23 parts by weight of diphenylamine-4-diazonium chloride are stirred at room temperature into 42 parts by weight of 85% phosphoric acid. A viscous solution is formed which is further stirred for half an hour at room temperature and then heated to 40 C. This temperature is maintained for a further 24 hours and the reaction is then completed. If desired, the phosphoric acid can be replaced by the same quantity of pyrophosphoric acid or metaphosphoric acid.

The condensation producta thick homogeneous mixturehas excellent keeping qualities which even allow it to be consigned for transport. It can be mixed with water and with many organic solvents, e.g., methanol or other aliphatic alcohols, dioxane, ethyleneglycol monomethylether, and dimethyl formamide. Thus, it is possible for the coating solution to be adapted so far as concerns the solvent to the material which is to be coated. The condensation product may also be used in admixture with water-soluble additives or with additives which are not soluble in water but are soluble in organic solvents. For many purposes the viscous reaction product can be used direct and without isolation which is very advantageous.

In the same manner, and with equally good results, one of the following compounds may be used instead of the diphenylamine-4-diazonium chloride for the condensation with formaldehyde in phosphoric acid:

3-methoxy-diphenylamine-4-diazonium chloride, 2-methoxy-diphenylamine-4-diazonium chloride, 3-methyl-diphenylamine-4-diazonium chloride, 4'-methoxy-diphenylamine-4-diazonium chloride, 3-ethoxydiphenylamine-4-diazonium chloride,

The condensation products are prepared in analogy to the preparation of the unsubstituted condensate described above.

Example VIII A presensitized printing foil is prepared as described in Example VII but the sensitizing solution contains, in addition to 1.25 percent of the condensate described in Example VII, 0.75 percent of an interpolymer containing carboxyl groups (85% vinyl chloride, 14% vinyl acetate, 1% maleic acid).

Example IX The procedure described in Example VII is followed, but the sensitizing mixture contains, as the light sensitive substance, a crude condensate prepared in accordance with Example VII but using for the condensation an equivalent quantity by weight of diphenylamine-4-diazonium bromide or diphenylamine-4-diazonium phosphate instead of diphenylamine-4-diazonium chloride.

Example X A 1 percent aqueous solution of polyvinyl phosphonic acid is applied by means of a cotton-wool pad to a paper sheet to which a thin aluminum foil is laminate. The foil is dried and then treated with a 2.5 percent aqueous solution of the condensation product described in Example VII. The light sensitive coating, which keeps well in the unexposed state, is exposed with a master and converted into a serviceable printing plate, preferably by wiping over with a cotton wool pad soaked in water.

Example XI An aluminum foil is coated in a rotating whirler With a solution consisting of 0.1 part by weight of polyvinyl phosphonic acid, 10 parts by weight of water, parts by weight of ethyleneglycol monomethyl ether, and 20 parts by weight of dimethyl formamide. After drying, the pretreated aluminum foil is coated with a solution containing 0.1 part by weight of a condensation product prepared from diphenylamine-4-diazonium phosphate and formaldehyde in phosphoric acid and precipitated in the form of an acid phosphate in a mixture made up of 18 parts by volume of 2.5 percent (by weight) phosphoric acid, 160 parts by volume of water, 1080 parts by volume of ethyleneglycol monomethyl ether, and 720 parts by volume of dimethyl formamide. The foil is then dried.

The light sensitive coating, which has excellent keeping qualities in the unexposed state, is exposed with a photographic negative and converted into a printing plate, advantageously by wiping over with 0.5 percent aqueous phosphoric acid. The printing plate is very serviceable and is very resistant during printing to the usual phosphoric acid anti-scumrning agents.

The acid phosphate of the condensation product from diphenylamine-4-diazonium phosphate and formaldehyde used for the preparation of the coating solution is prepared as follows:

5.63 parts by weight of paraformaldehyde are condensed in 42.6 parts by volume of 85 percent phosphoric acid with 50 parts by weight of diphenylamine-4-diazonium phosphate for 24 hours, at 40 C. 50 parts by weight of the crude condensation mixture are diluted with 125 parts by volume of methanol and the resultant solution, heated to 40 C., is stirred in a thin stream into 500 parts by volume of isopropanol which is kept vigorously agitated. The fine precipitate is stirred for 10 minutes at room temperature and then further stirred at 30-35 C. until the original precipitate has changed into a sandy, quickly settling powder. This is filtered off, suspended in 100 parts by volume of fresh isopropanol, again filtered off, washed with isopropanol and dried at 30-40 C.

The diphenylamine-4-diazonium phosphate may be prepared as follows: A solution of 1100 parts by weight of Na I-IPO .12H O and 40 parts by volume of 85 percent phosphoric acid in 6000 parts by volume of distilled water is heated to 70 C. and poured into a solution of 500 parts by weight of diphenylaminel-diazonium chloride in 1000 parts by volume of 85 percent phosphoric acid, with thorough stirring. The diazonium phosphate precipitates out in orange-colored crystals. The reaction mixture is cooled to 20 C. and the diazonium phosphate is filtered off. It is washed four times with 500 parts by volume of distilled water, once with 500 parts by volume of ethanol, and twice with 500 parts by volume of isopropyl ether, and then dried in the air. 560 parts by weight are obtained of chloride-free diphenylamine-4- diazonium phosphate of the composition C H NHC H N H PO Example XII A foil of virgin aluminum sheet is immersed for 120 seconds at 85 C. in water containing 1 percent of polyvinyl phosphonic acid and 1 percent of vinyl phosphonic acid. After the aluminum foil has been rinsed down with water and dried, it is coated with a solution consisting of 0.14 part by weight of a condensation product prepared from diphenylamine-4-diazonium chloride and formaldehyde in hydrochloric acid and separated in the form of the chloride, and 0.13 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. The preparation of the printing plate is as described in Example VII.

A planographic printing plate of equivalent value is obtained if the solution used for the sensitization of the pre-treated aluminum foil contains, instead of 0.14 part by weight of the condensation product specified above, 0.16 part by weight of a condensation product prepared from diphenylamine-4-diazonium chloride and formaldehyde in 66 percent hydrobromic acid and precipitated in the form of the bromide or 0.11 part by weight of a product prepared from diphenylamine-4-diazonium chlo- 8 ride and formaldehyde by condensation in 40 percent bydrofluoric acid.

The condensation product is prepared as follows:

Condensation in hydrochloric acid: 46 parts by weight of diphenylamine-4diazonium chloride and 6 parts by weight of paraformaldehyde are stirred in 200 parts by volume of concentrated hydrochloric acid for eight hours at 50 C. and then for twelve hours at room temperature. The mixture is evaporated in vacuo to dryness at a bath temperature of 50 to 55 C. The residue consists of a mixture of the neutral and the acid chloride of the condensation product.

Condensation in hydrobromic acid: 138 parts by weight of diphenylamine-4-diazonium chloride, 18 parts by weight of paraformaldehyde and 300 parts by volume of 66% hydrobromic acid are mixed together and heated for seven hours to 50 C. The mixture is then evaporated in vacuo at a maximum temperature of 70 C. to dryness. The condensation product is obtained in the form of the acid bromide.

Condensation in hydrofluoric acid: 23: 15 parts by weight of diphenylamine-4-diazonium chloride, 3.3 parts by weight of paraformaldehyde and 50 parts by volume of 40% hydrofluoric acid are mixed together and the mixture is heated for 20 hours to 40 C. and for 16 hours at 50 C. The solution is evaporated at 50 C. by passing a current of air through it and it is completely dried in vacuo over potassium hydroxide. A product which contains one fluorine ion and one chlorine ion to each diazonium group is obtained.

Example XIII A foil of virgin aluminum sheet is immersed for 30 second at 70 to C. in a 0.1% solution of polyvinyl phosphonic acid. The foil is rinsed with water and dried and then coated with a solution consisting of 0.1 part by weight of a condensation product prepared from diphenylamine-4-diazonium chloride and formaldehyde in phosphoric acid and precipitated in the form of the chloride in 100 parts by volume of glycol monoethyl ether. The printing plate is prepared as described in Example VII.

The condensation product is prepared as follows:

3.3 parts by weight of paraformaldehyde and 23 parts by weight of diphenylamine-4-diazonium chloride are mixed into 56.5 parts by weight of 85% phosphoric acid, with stirring. Condensation is brought about by heating the mixture for 24 hours to 40 C. and then diluting with 320 parts by volume of methanol. With constant agitation, 50 parts by weight of calcium carbonate are added gradually to the reaction mixture until the pH value of the mixture is about 6. The inorganic salts that are then formed are filtered off by means of a suction filter and the filtrate is evaporated to dryness.

Example XIV A thin strip of sheet aluminum is drawn through a bath containing a 1 percent solution of polyvinyl phosphonic acid in water at 80 to C. Subsequently, the aluminum sheet is rinsed with water, dried, and coated with a light sensitive solution containing 0.5 part by weight of the phosphoric acid condensate of paraformaldehyde and 4-methyl-diphenylamine-4-diazonium sulfate described below in 99.5 parts by weight of ethyleneglycol monoethylether.

A printing plate is prepared as described in Example VII.

The phosphoric acid condensationproduct used for sensitizing the solution is prepared as follows:

In 12 parts by volume of 97 percent phosphoric acid are dissolved 3 parts by weight of a condensation product prepared by condensing 20 parts by weight of 4'- methyl-diphenylamine-4-diazonium sulfate with 1.96 parts by weight of paraformaldehyde in 42 parts by volume of 78 percent sulfuric acid and obtained in the form of the chloride. A stream of dry air is passed through the reaction mixture at a temperature of 40 C., until the mixture is free from chlorine ions. The mixture is then diluted with 32 parts by volume of methanol and poured into 250 parts by volume of isopropanol. The -precipitate which forms is drawn off, washed with isopropanol and acetone, and dried under vacuum.

Similar results are obtained if an aluminum sheet pretreated as above is coated with a solution which contains, instead of the condensation product mentioned above, a product which was prepared by condensation of paraformaldehyde with 3-methyl-diphenylamine-4-diazonium chloride, 3-ethoxy-diphenylamine-4-diazonium chloride, 2 methoxy diphenylamine 4 diazonium chloride, or 2-methoxy-diphenylamine-4-diazonium chloride and converted into the solid acid phosphate.

Example XV A thin strip of sheet aluminum is drawn through a bath which contains a 0.1 percent solution of polyvinyl phosphoric acid in ethyleneglycol monomethylether at a temperature of 40 C. Subsequently, the aluminum sheet is dried and coated with a light sensitive solution containing 0.1 part by weight of the chloride of a condensation product of paraformaldehyde and 4-methyldiphenylamine-4-diazonium sulfate described below in 99.9 parts by weight of ethyleneglycol monomethylether.

A printing plate is prepared as described in Example VII.

The chloride of a condensation product used in the sensitizing solution is prepared as follows:

Over a period of minutes, parts by weight of 4-methyl-diphenylamine-4-diazonium sulfate are introduced into a solution of 1.96 parts by weight of paraformaldehyde in 42 parts by volume of 78 percent sulfuric acid. The condensation mixture is agitated, first for one hour at room temperature and then for 90 minutes at a temperature of 40 C., and is then left standing overnight at room temperature. Subsequently, it is diluted with 150 parts by volume of water and a saturated barium chloride solution is added until neither an excess of barium nor sulfate ions can be detected. After removal of the barium sulfate, the solution is evaporated to dryness under vacuum at temperatures up to 60 C.

What is claimed is:

1. A method for improving the receptivity for adhesively applied coatings of an aluminum surface which comprises treating the surface with a solution comprising at least one compound selected from the group consisting of an organic phosphonic acid and the esters and salts thereof, and drying.

2. A method according to claim 1 in which the solution has a concentration of about 0.001 to 10 percent by Weight.

3. A method according to claim 1 in which the solution also contains a hydrophilic colloid.

4. A method according to claim 1 in which the phosphonic acid is polyvinyl phosphonic acid.

5. A method according to claim 1 in which the phosphonic acid is S-nitronaphthalene phosphonic acid.

6. A method according to claim 1 in which the phosphonic acid is vinyl phosphonic acid.

7. A presensitized printing plate comprising an aluminum base, a first layer comprising at least one compound selected from the group consisting of an organic phosphonic acid and the esters and salts thereof, and a second reproduction layer on the first layer.

8. A presensitized printing plate according to claim 7 in which the reproduction layer is light sensitive.

9. A presensitized printing plate according to claim 7 in which the reproduction layer is heat sensitive,

10. A presensitized printing plate according to claim 7 in which the first layer also contains a hydrophilic colloid.

11. A presensitized printing plate according to claim 7 in which the phosphonic acid is polyvinyl phosphonic acid.

12. A presensitized printing plate according to claim 7 in which the phosphinic acid is S-nitronaphthalene phosphonic acid.

13. A presensitized printing plate according to claim 7 in which the phosphonic acid is vinyl phosphonic acid.

14. A presensitized printing plate according to claim 7 in which the phosphonic acid is 2-phosphonoethane-lsulfonic acid.

15. A presensitized printing plate according to claim 7 in which the phosphonic acid is vinyl phosphonic acid monomethyl ester.

16. A presensitized printing plate according to claim 7 in which the phosphonic acid is vinyl phosphonic acid monoethyl ester.

17. A presensitized printing plate according to claim 7 in which the reproduction layer comprises a condensation product of 4-diazodiphenylamine and formaldehyde.

18. A presensitized printing plate according to claim 7 in which the reproduction layer comprises a benzoquinone diazide.

19. A presensitized printing plate according to claim 7 in which the reproduction layer comprises 4-diazodiphenylamine chloride.

20. A presensitized printing plate according to claim 7 in which the reproduction layer comprises a naphthoquinone diazide sulfonic acid ester.

21. A presensitized printing plate according to claim 7 in which the reproduction layer comprises a thiazolidon.

22. A process for making a printing plate which comprises exposing a coated aluminum base material to radiation under a master, the coating comprising a first layer comprising at least one compound selected from the group consisting of an organic phosphonic acid and the esters and salts thereof and a second reproduction layer on the first layer, and developing the resulting image, whereby the coating is removed from the base material in the imagefree areas thereof.

23. A process according to claim 22 in which the radiation is light.

24. A process according to claim 22 in which the radiation is heat.

25. A process according to claim 22 in which the first layer also a hydrophilic colloid.

26. A process according to claim 22 in which the phosphonic acid is polyvinyl phosphonic acid.

27. A process according to claim 22 in which the phosphonic acid is S-nitronaphthalene phosphonic acid.

28. A process according to claim 22 in which the phosphonic acid is vinyl phosphonic acid.

29. A process according to claim 22 in which the phosphonic acid is Z-phosphonoethane-l-sulfonic acid.

30. A process according to claim 22 in which the phosphonic acid is vinyl phosphonic acid monomethyl ester.

31. A process according to claim 22 in which the phosphonic acid is vinyl phosphonic acid monoethyl ester.

32. A process according to claim 22 in which the reproduction layer comprises a condensation product of 4- diazo-diphenylamine and formaldehyde.

33. A process according to claim 22 in which the reproduction layer comprises a benzoquinone diazide.

34. A process according to claim 22 in which the reprcpduction layer comprises 4diazodiphenylamine chlo- I'l e.

35. A process according to claim 22 in which the reproduction layer comprises a naphthoquinone diazide sulfonic acid ester.

36. A process according to claim 22 in which the reproduction layer comprises a thiazolidon.

37. A presensitized printing plate according to claim 7 in which the reproduction layer comprises a condensation product of 3-methoxy-diphenylamine-4-diazonium chloride and formaldehyde.

38. A process according to claim 22 in which the re- References Cited by the Examiner UNITED STATES PATENTS 2,641,551 6/1953 Smith et a1. 2,725,310 11/1955 McBride 117-75 12 Lowell. Cohn 9686 X Gumbinner 9686 X Dowdall et al 9675 NORMAN G. TORCHIN, Primary Examiner.

HAROLD N. BURSTEIN, Examiner.

Claims (2)

1. A METHOD OF IMPROVING THE RECEPTIVITY FOR ADHESIVELY APPLIED COATINGS OF AN ALUMNIUM SURFACE WHICH COMPRISES TREATING THE SURFACE WITH A SOLUTION COMPRISING AT LEAST ONE COMPOUND SELECTED FROM THE GROUP CONSISTING OF AN ORGANIC PHOSPHONIC ACID AND THE ESTERS AND SALTS THEREOF, AND DRYING.

7. A PRESENSITIZED PRINTING PLATE COMPRISING AN ALUMINUM BASE, A FIRST LAYER COMPRISING AT LEAST ONE COMPOUND SELECTED FROM THE GROUP CONSISTING OF AN ORGANIC PHOSPHONIC ACID AND THE ESTERS AND SALTS THEREOF, AND A SECOND REPRODUCTION LAYER ON THE FIRST LAYER.