CA1299007C - Hydrophilized support materials for offset printing plates - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

The invention relates to a support material based on aluminum, which carries a hydrophilic coating which is composed of a polymer of acrylamidoisobutyl-enephosphonic acid, a copolymer of this acid with acry-lamide or salts of the polymers with an at least divalent metal cation. The hydrophilized material is used as a support for light-sensitive substances for the preparation of printing plates.

Description

~2~0~)7 HYDROPHILIZED SUPPORT MI~TERIALS FOR OFFSET
PRINTING PLATES

BACKGROUND OF T!HE INVENTION

The invention relates to support materials in the form of plates, sheets or webs for offset printing plates, based on aluminv,m with a hydrophilic coating, to a process for the preparation of these materials and to the use of the materials in the production of offset printing plates.
Support materials for offset printing plates are provided, either by the user directly or by the manufacturer of pre-coated printing plates, on one side or both sides ~ith a light-sensitive layer ~copying layer), with the aid of which a printing image is pro-duced by photomechanical means. After the production of the printing image, the support carries the printing image areas and at the same time forms the hydrophilic image background for the lithographic printing process in the image free areas tnon-image areas).
A support for light-sensitive material for the preparation of lithographic plates must therefore meet the following re~uirements:
- Those parts of the light-sensitive layer which are relatively more soluble aftex the exposure must be readily removable from the support by development, without ~L2~90(~7 leaving a residue, in order to produce hydrophilic non-image areas.
- The support bared in the non-image areas mus~ have a high affinity for water, i.e.
must be highly hydrophilic, so that, in the lithographic printing process, it absorbs water rapidly and durably and has a sufficiently repellent action on the greasy printing ink.
_ There must be a sufficient de~ree of adhesion of the light-sensitive layer before exposure and of the printing areas of the layer after exposure.
Foils of aluminum, steel, copper, brass or ~5 zinc and also plastic sheets or paper can be used as the base material for such supports. These raw materials are converted by suitable operations such as, for example, graining, mattchromium plating, super-ficial oxidation and/or application of an interlayer into supports for offset printing plates. Aluminum, which nowadays is presumably the most widely used base material for offset printing plates, is superficially roughened according to known methods by dry brushing, wet brushing, sandblasting or chemical and/or electrochemical treatment. To improve the abrasion resistance, the roughened substrate can also be sub-jected to an anodizing step in order to build up a thin oxide layer.
In practice, the support materials, in par-ticular anodically oxidized support materials based on aluminum, are frequently subjected to a further treat-ment step before the application of a light-sensitive layer, in order to improve the layer adhesion, to intensify the hydrophilic character and/or to facili-~2~)07 tate the development oE the light-sensitive layers;
these steps include, for example, the following methods:
In U.S. Patent No. 2,714,066, U.S. Patent No.
3,181,461 and U.S. Patent No. 3,280,734 or U.S. Patent No. 3,902,976, processes for the hydrophilizing oE
printing plate support materials based on aluminum which may have been anodically oxidized are described, wherein these materials are treated with an aqueous sodium silicate solution with or without applying an electric current.
It is known from U.S. Patent No. 3,276,86B and U.S. Patent No. 4,153,461 to use polyvinylphosphonic acid or copolymers based on vinylphosphonic acid, acry-lic acid and vinyl acetate for the hydrophilizing of printing plate support materials based on aluminum which may have been anodically oxidized. The use of salts of these compounds is also mentioned, but not specified in more detail.
The use of complex fluorides of titanium, zir-conium or hafnium according to U.S. Patent- No.
3,~40,050 likewise leads to additional hydrophilizing of aluminum oxide layers on printing plates support materials.
In addition to these hydrophilizing methods which have become particularly widely known, the use o~
the following polymers in this field of application has also been described, for example:
In German Auslegeschrift No. 1,056,931, the use of water-soluble~ linear copolymers based on alkyl vinyl ethers and maleic anhydrides in light-sensitive layers for printing plates is described. Amongst these copolymers, those are particularly hydrophilic in which the maleic anhydride component was not reacted, or more or less completely reacted, with ammonia, an alkali metal hydroxide or an alcohol.

~2~7 German Auslegeschrift No. 1,091,433 (equiva-lent to sritish P~tent No. 815,471) has disclosed the hydrophiliæing oE printing plate support materials based on metals by means of film-forming organic poly-mers such as polymethacrylic acid or sodium car-boxymethylcellulose or sodium hydroxyethylcellulose on aluminum supports or with a copolymer of methyl vinyl ether and maleic anhydride on magnesium supports.
For the hydrophilizing of printing plate sup-port materials of metals, initially water-soluble poly-functional amino/urea/aldehyde synthetic resins or sulfonated urea/aldehyde synthetic resins, which are cured on the metal support in a water-insoluble state, are used according to German Auslegeschrift ~o.
1,173,917 (equivalent to British Patent No. 907,718).
For preparing a hydrophilic layer on printing plate support materials according to U.S. Patent No.
3,232,783, a) an aqueous dispersion of a modified urea/formaldehyde resin, an alkylatèd methylolmelamine resin or a melamine/formaldehyde/polyalkylenepolyamine resin is first applied to the support, then b) an aqueous dispersion of a polyhydroxy or polycarboxy com-pound, such as sodium carboxymethylcellulose, is applied and finally the base so coated is treated c) with an aqueous solution of a ~r, ~f, Ti or Th salt.
In U.S. Patent No. 2,9~1,204, a copolymer which, in addition to acrylic acid, acrylate, acryla-mide or methacrylamide units, also contains Si-trisubstituted vinylsilane units is described as a hydrophilizing agent for printing plate support materials.
The use of polyacrylic acid as a hydrophi-lizing agent for printing plate support materials of - aluminum, copper or zinc is known from U.S. Patent NoO
3,2g8,852.
The hydrophilic layer on a printing plate sup-~2~ 7 port ma-terial according to U.S. Patent No. 3,733,200 is formed from a water-insoluble hydrophilic acrylate or methacrylate homopolymer or copolymer with a water absorption of at least 20~ by weight.
In German ~uslegeschrift No. ~,305,231 (equivalent to sritish Patent No. 1,414~575), hydrophi-lizing of printing plate support materials is described, wherein a solution or dispersion of a mix-ture of an aldehyde and a synthetic polyacrylamide is applied to the support.
U.S. Patent No. 3,861,917 has disclosed hydrophilizing of roughened and anodically oxidized aluminum printing plate supports by means of ethylene or methyl vinyl ether/maleic anhydride copolymers, polyacrylic acid, carboxymethylcellulose, sodium poly-(vinylbenzene-2,4-disulfonate) or polyacrylamide.
In U.S. Patent No. 3,860,426, a hydrophilic adhesion layer for aluminum oEfset printing plates is described, which is located between the anodically oxi-dized surface of the printing plate support and thelight-sensitive layer and, in addition to a cellulose ether, also contains a water-soluble Zn, Ca, Mg, Ba, Sr, Co or Mn salt. The layer weight of cellulose ether in the hydrophilic adhesion layer is 0.2 to 1.1 mg/dm2, and the same layer weight is also given for the wa~er-soluble salts. The mixture of cellulose ether and salt is applied in an aqueous solution, if appropriate with addition of an organic solvent and/or a surfactant, to the support.
3Q Aqueous solutions of acrylic acid, polyacrylic acid, polymethacrylic acid, polymaleic acid or copoly-mers of maleic acid with ethylene or vinyl alcohol are used according to U.S~ Patent No. 3,672,966 for com-pacting anodically oxidized aluminum surfaces after they have been sealed, in order to avoid seal deposits.
The hydrophilizing agents for printing plate support materials according to U.S. Patent No. 4,049,746 contain salt-like reaction products of water-soluble pol~acrylic resins ~ith carboxyl groups and polyalkyleneimine~urea~aldehyde resins.
In British Application No. 1,2~6,696, publlshed September 15, 1971l hydrophilic colloids such as hydroxyethyl-cellulose, polyacrylamide, polyethylene oxide, polyvinyl-pyrrolidone, starch or gum arabic are described as hydrophilizing agents for anodically oxidized aluminum printing plate supports.
Japanese Patent Appl.ication No. 64~23,982 published October 27, 1964~ has disclosed hydrophilizing of metal printing plate supports with polyvinylbenzenesulfonic acid.
In the state of the art, the use of those metal complexes for hydrophilizing printing plate support materials has also been disclosed which contain low-molecular ligands; these include, for example:
- Complex ions of divalent or polyvalent metal cations and ligands such as ammonia, water, ethylenediamine, nitrogen oxide, urea or ethylene-diaminetetraace-tate, according to U.S. Patent No.
~,208,212, - iron cyanide complexes such as K4[Fe(CN)~l or Na3[Fe~CN)6} in the presence of heteropolyacids such as phosphomolybdic acid or its salts and of phosphates, according to U.S. Patent No. 3,769,043 or/and U.S. Patent No. 4,420,549, or 3L2~7 - iron cyanide complexes in the presence of phosphates and complex formers such as ethylene-diaminetetraacetic acid for electrophotographic printin~ plates with a zinc oxide surface, according to U.S. Patent No. 3,672,385.

6a ~' ~2~

U.~. Patent No. 4,427,765 describes a process in which salts o~ polyvinylphosphonic acids, polyvi-nylsulfonic acids, polyvinylmethylphosphinic acids and other polyvinyl compounds are used as post-treatment agents.
In U.S. Patent No. 4,~14,531, a process for treating image-bearing offset printing plates with polyacrylamide or a mixture of polyacryla~ide and polyacrylic acid is used.
A copolymer of acrylamide and vinyl monomers is used in USSR No. 647,142 for hydrophilizing offset printing plates.
In German Patent No. 2,615,075 (equivalent to British Patent No. 1,495,895), a polyacrylamide is used 1~ for the same purpose.
German Patent No. 1,091,433 describes a pro-cess for the post-treatment of offset printing plate supports with polymers of methacrylic acid, methyl vinyl ether and maleic anhydride.
Acrylamide for the treatment of printing plate supports is also mentioned in German Offenlegungs-schrift No. 2,540,561.
For the same purpose, in particular for improving the storage stability of prin~ing plates, 25 German Offenlegungsschrift NQ. 2,9~7,7~8 describes inter alia Ni salt solutions of acrylamide and acrylic acid as well as acryla~ide and vinylpyrrolidone.
All the methods described above, however, involve more or less serious disadvantages so that the support materials produced in this way frequently no longer meet the current requirements of offset prin-ting:
- Thus, after the treatment with alkali metal silicates, which lead to good deve-loping properties and hydrophilic character, a certain deterioration in the storage stability of light-sensitive layers applied thereto must be accepted.
- ~lthough the complexes of transition metals promote in principle the hydrophi-lic character of anodically oxidized alu-minum surfaces, they have the disadvantage of being very readily soluble in water, so that they can easily be removed when.the layer is developed with aqueous developer systems which of late increasingly contain surfactants and/or chelate formers which have a high affinity to these metals. ~s a result, the concentration of the transition metal complexes on the surfaces is reduced to a greater or lesser extent, and this can lead to a weakening of the hydrophilic effect.
- In the treatment of supports with water-soluble polymers, the good solubility of the latter, particularly in aqueous-alkaline developers t such as are predomi-nantly used for the development of positive-working light-sensitive layers, also leads to a marked weakening of the hydrophilizing effect.
- In polymers containing acid groups, an adverse effect arises since free anionic acid groups can interact with the diazo cations of negative-working light-sensitive layers~ so that a marked dye staindue to retained diazo compounds remains after development on the non-image areas.

- The combination of a mixture of a water-soluble polymer, such as a cellulose ether, and a water-soluble metal salt also leads, since the layer weights and hence the layer thickness are selected to be relatively high (German ~uslegeschrift No. 2,364,177), to reduced layer adhesion ~hich can manifest itself, for example, in disbonding of image areas by parts of the developer li~uid during development.

SUMMARY OF THE_INVENTI021 It is accordingly an object of the invention to provide support materials for offset printing plates having good hydrophilizing properties.
It is another object of the invention to pro-vide support materials, as above, which are equally suitable as supports for positive-working, negative-working or electrophotographic light-sensitive layers.
~t is yet another object of the invention to provide support materials, as above, which have good storage stability.
It is still another object of the invention to provide support materials, as above~ in whic~ no reac-tions occur between a hydrophilizing agent and the light-sensitive layer, and which do not reduce the layer adhesion.
These objects are achieved by a support material for offset printing plates, which comprises an aluminum-containing base material, and a hydrophilic coating applied to at least one side of the aluminum containing base material, the hydro~hilic coating comprising a phosphonic acid compound selected from the group consisting of a polymer of acrylamidoisobutylene phosphonic acid, a copolymer of acrylamide and acrylamidoisobutylene-_g _ 12~007 phosphonic acid, a salt of either of the above with anat least divalent metal cation, and combinations of any of the above.
The objects of the invention are also achieved by a process for the preparation of a support material for offset printing plates which comprises coating an aluminum-containing base material, with the above-described phosphonic acid compound, the phosphonic acid com-pound being in the form of an aqueous solution having a concentration of from about 0.02 to about 5.0~ by weight, and drying the layer. The coating step is performed by dipping or electrochemical treatment.
When the phosphonic acid compound is a polymer or copolymer salt, the coating process can be performed in two steps, in which the polymer or copolymer is coated onto the aluminum-containing base material, followei by treating the base material with a solution of the metal cation salt which reacts with the polymer or copolymer coating.
DETAILED DESCRIPTION OF THE PREFERRED EMOBODIMENTS

The invention starts from a support material in the form of plates, sheets or webs for offset printing plates, composed of aluminum, which may have been pretreated, or one of its alloys carrying on at least one side a hydrophilic coating of a phosphonic acid compound.
The distinctive feature is that the hydrophi-llc coating comprises a) a polymer of acrylamidoisobu-tylenephosphonic acid or b) a copolymer of acrylamide and acrylamidoisobutylenephosphonic acid or c) a salt of a) or b) with an at least divalent metal cation. In the case of the copolymers of b) and the copolymer salts of c), the acrylamide/acrylamidoisobutylene phosphonic acid ratio is between about 99:1 and about l:99 on a molar basis, and preferably between about 3:97 and about gO:lO on a molar basis.
In the copolymeric salts, 1 to 3, preferably 2, coordination sites of the metal cation are occupied by the functional groups of the polymer.
To prepare the reaction products of the variants c), the metal cations are in general used in the form of their salts with mineral acid anions or as acetates; the divalent, trivalent or tetravalent cations, in particular the divalent cations, are pre-ferred here. The cations are especially V5+, Bi3+, Al3+, Fe3+, Zr4+, Sn4+, Ca2~, Ba2+, Sr2+, Ti3+, Co2+, Fe2+, Mn2+, Ni2+, CU2+~ Zn2+ or Mg2+ ions.
These reaction products can be prepared in a simple manner irl aqueous solutions at temperatures of from about 20 to about 100C, preferably at from about 25 to about 40C. The metal salt dissolved in water, or if necessary dissolved in dilute mineral acid, is slowly added dropwise to the aqueous po]ymer solution.
The conversion of the reaction components to the pro-ducts described above then starts immediately. The rapid start of the reaction manifests itself - as a function of the metal cation used - in the immediate onset of a color change of the solution or by the for-mation of a precipitate.
For purification, the products can be pre-cipitated by neutralizing the reaction solution with dilute alkali metal hydroxide or ammonia solutions, ~he unconverted starting products remaining in the solu-tion. The yields of these reactions are over 90%. Itis also possible, instead of the acid forms of the polymers, as described, to employ their salt forms with a monovalen-t cation, such as a sodium or ammonium salt.
~he chemical structure of the polymer/metal complexes according to the invention can be represented as follows:

A ¦ A

PO3H ¦ PO3H
A
polymer chain _ HP( )3 ¦ PO3H

10 with especially A l \ A

M = a central ion and, in the case of 2-valent metal cat.ions, A = B = H2O
or, in the casP of 3-valent metal cations A = H2O
and B = NO3-, Cl-, HSO4-, H2PO4-, CH3COO-, OH- or similar anions.
Such complexes are formed in particular when the polymer solution is slowly added to an excess of the metal salt.
For treating the aluminum surface for the pre-paration of the support materials according to the invention for offset printing plates, the a~ueous solu-tions of the copolymers are employed in concentrations of from about 0.02 to about 5% by weight, preferably in concentrations of from about Ool to about 1% by weight.
For treating the substrates for the prepara-tion of the support materials according to the inven-tion for offset printing plates with the salts of the copolymers, the isolated and dried reaction products are preferably dissolved in solutions of from about 0~1 ~L2~'7 to about 10% by weight mineral acids, in partiular, solutions of from about 0.5 to about 3~ by weight mineral acids, preEerably phosphoric acid, in con-centrations of from about 0.05 to about 5% by weight in particular in concentrations of from about 0.1 to about 1% by weight.
The treatment of these substrates with these solutions is advantageously carried out by dipping the formats or by passing the substrate web through a bath 10 of these solutions. Temperatures from about 20 to about 95C, preferably from about 25 to about 60C, and residence times from about 2 seconds to about 10 minu-tes, preferably from about 10 seconds to about 3 minu-tes, prove to be the most suitable for use in practice.
~n increase in the bath temperature accelerates the chemisorption of the copolymers and the polymer metal complexes on the substrate. This allows a considerable reduction of the residence times, in particular in the case of continuous web treatment. The dipping treat-ment is then advantageously followed by a rinsing stepwith water. The substrate thus treated is then dried, advantageously at temperatures from about 110 to about 130C.
The treatment of the aluminum substrate with the salts of the copolymers can also be carried out as a two-stage process. In this case, the substrate is dipped in the first step, for example, into an about 0.01 to about 10%, preferably about 0.1 to about 5%, aqueous solution of the starting polymer. Without prior rinsing or drying, the substrate can then be transferred into a second bath which contains an about 0.1% to saturated, preferably about 0.5 to about 10~, aqueous salt solution with the above-mentioned polyva-lent metal ions. Rinsing and drying is carried out as in the one-stage process. In the two-stage treatment, the reaction products described above are formed on the 0~7 substrate during the treatment. UsLng this process variant, even the trivalent metal ion reaction products sparingly soluble in strongly acidic media can be applied to ~he substrate.
~ determination of the weight of the hydrophi-lic coating applied raises problems, since even small quantities of the applied product show marked effects and are relatively strongly anchored in and on the sur-face of the support material. It can be assumed, however, tha~ the quantity applied is significantly below 0.1 mg/dm2, in particular below 0.08 mg/dm2.
The support materials according to the inven-tion, thus prepared, can then be coated with various light-sensitive layers for the production of offset printing plates.
Suitable substrates for the preparation of the support materials according to the invention include those of aluminum or one of its alloys. These include, for example:
- "pure aluminum" (DIN material No.

3.0255), i.e. composed of > 99.5% of Al and the following permissible impurities of (total 0.5% maximum) 0.3% of Si, 0.4%
of Fe, 0.03~ of Ti, 0.02% of Cu, 0.07% of Zn and 0.03% of others, or "Al alloy 3003" (comparable with DIN
material No. 3.0515), i.e. composed of >
98.5% of Al, 0 to 0.3% of Mg and 0.8 to 1.5% of Mn as the alloy constituents and the following permissible impurities o~
0.5~ of Si, 0.5% of Fe, 0.2% of Ti, 0.2%
of Zn, 0.1% of Cu and 0.15~ of others.
However, the process according to the inven-tion can also be transferred to other aluminum alloys.

0~;7 The aluminum support materials for printing plates, as very frequently encountered in practice, are in general also roughened mechanically (for example by brushing and/or abrasive treatments), chemically (for example by etching) or electrochemically (for example ~y an alternating current treatment in aqueous HCl or HNO3 solutions), before the light-sensitive layer is applied. For the present inven-tion, aluminum printing plates with electrochemical roughening are used espe-cially.
In general, the process parameters in theroughening stage are within the following ranges: the temperature of tbe electrolyte between about 20 and about 60C, the concentration of active substance (acid, salt) between about 5 and about 100 g/l, the current density between about 15 and about 130 A/dm2, the residence time between about 10 and about 100 seconds and the elect~olyte flow velocity on the sur-face of the workpiece to be treated between about 5 and about 100 cm/second; the current type used is in most cases alternating current, but modified current types, such as an alternating current with different amplitu-des of current intensity for the anode current and cathode current are also possible.
The mean peak-to-valley height Rz of the roughened surface then is in the range from about 1 to about 15 /um, in particular in the range from about 4 to about 8 /um.
The peak-to-valley height i5 determined in accordance with DIN 4768 ~October 1970 edition), and the peak-to-valley height Rz is then the arithmetic mean of the individual peak-to-valley heights for five continuous individual measurement sections. The indi-vidual peak-to-valley height is defined as the distance of the two parallels to the center line, which touch the roughness profile at the highest and lowest point ~2~ 7 respectively within the individual measurement sec-tions. The individual measurement section is the fifth part of the length, projected perpendicularly onto the center line, of that part of the roughness profile which is used directly for evaluation. The center line is the line parallel to the general direction of the roughness profile of tha form of the geometrically ideal profile, which line divides the roughness profile such that the sums of the areas filled with material above it and of the areas free of material below it are equal.
The electrochemical roughening process is then followed, in a further process stage which may h~ve to be applied, by an anodic oxidation of the aluminum, for example in order to improve the abrasion and adhesion properties of the surface of the support material. The conventional electrol~tes such ~s H2S4l H3PO4- H2C24l amidosulfonic acid, sulfosuccinic acid, sulfosalicylic acid or mixtures thereof can be used for the anodic oxidation. Reference is made, for example, to the following standard methods for the use of aqueous electrolytes containing H2SO4 in the anodic oxidation of aluminum (in this connection, see, for example, B.M.
Schen~, Wer~stoff Aluminium und seine anodische Oxydation tThe material aluminum and its anodic oxidation], Francke Verlag - Berne, 1948, page 760;
Praktische Galvanotechnik tElectroplating Practice], Eugen G. Leuze Verlag - Saulgau, 1970, pages 395 et seq. and pages 518/519; W. Hubner and C.T. Speiser, Die Praxis der anodischen Oxydation des Aluminiums tPractice of the anodic oxidation oE aluminum], Aluminium Verlag - Dusseldorf, 1977, 3rd edition, pages 137 et seq.):
- The direct-current sulfuric acid process, in which the anodic oxidation is carried out for 10 to 60 minutes in an aqueous electrolyte of usually about 230 g of H2SO4 per 1 liter oE solution at 10 to 22C and a current density of 0.5 to 2.5 ~/dm2. The sulfuric acid concentration in the aqueous electrolyte solution can here also be reduced to 8 to 10% by weight of H2SO4 ~about 100 g of H2SO4/1) or increased to 30% by weight (365 g of H2SO4/1) and higher.
- The "hard anodizing" is carried out with an aqueous electrolyte, containing H2SO4, of a concentration of 166 g of H2SO4/1 (or about 230 g of H2SO4/1) at an oper~
ating temperature of 0 to 5C, at a current density of 2 to 3 A/dm2, a rising voltage o~ about 25 to 30 V at the start and about 40 to 100 V toward the end of the treatment and for 30 to 200 minutes.
In addition to the processes, already men-tioned in the preceding paragraph, for the anodic oxi-dation of printing plate support materials, the ~ollowing processes can also be used, for example: the anodic oxidation of aluminum in an electrolyte which contains aqueous H2SO4 and the A13+ ion content of 25 which is adjusted to values of more than 12 g/1 (according to U.S. Patent No. 4,211,619), in an aqueous electrolyte con-taining H2SO4 and H3PO4 (according to U.S. Patent No. 4.049,504) or in an aqueous electro-lyte containing H2SO4, H3PO4 and A13~ ions (according to U.S. Patent No. 4,229,226).
Direct current is preferably used for the ano-dic oxidation, but alternating current or a combination of these current types (for example direct current wit~
a superposed alternating current) can also be used.
The aluminum oxide layer weights are in the range of from about 1 to about 10 g/m2, corresponding to a layer thickness of from about 0.3 to about 3.0 /um.
Suitable light-sensitive layers are in prin-ciple all those which, after exposure, if appropriate with subsequent development and/or fixing, give an imagewise surface, which can be used for printing.
They are applied to one of the conventional support materials either by the manufacturer of presensitized printing plates or directly by the user.
In addition to the layers which contain silver halides and are used in many fields, various other layers are also known, such as are described, for example, in "Light-Sensitive Systems" by Jaromir Kosar, published by John Wiley & Sons, New York 1965: colloid layers containing chromates and dichromates (Kosar t chapter 2); layers which contain unsaturated compounds and in which these compounds are isomeri~ed, rearranged, cyclized or crosslinked on exposure (Rosar, chapter 4); layers which contain photopolymerizable compounds and in which monomers or prepolymers poly-merize on exposure, i appropriate by means of an ini-tiator (Xosar, chapter 5); and layers containing o-diazo-quinones, such as naphthoquinone-diazides, p-diazo-quinones or diazonium salt condensates (Kosar~
chapter 7). The suitable layers also include electrophotographic layers, that is to say iayers which contain an inorganic or organic photoconductor. In addition to the light-sensitive substances, these layers can of course also contain further constituents such as, for example, resins, dyes or plasticizers.
In particular, the following light-sensitive compositions or compounds can be used for coating the support materials prepared by the process according to the invention:
Positive-working o-quinone-diazide compounds, preferably o-naphthoquinone-diazide compounds, which are described, for example, in German Patent Nos.
854,890, 865,109, 879,~03, 894,959, 938,233, 1,109,5~1, 1,144,705, 1,118,606, 1,120,273 and 1,124,817.
Negative-working condensation products of aro-matic diazonium salts and compounds with active car-bonyl groups, preferably condensation products of diphenylaminedia~onium salts and formaldehyde, which are described, for example, in German Patent ~os.
596,731, 1,138,399, 1,138,400, 1,138,401, 1,142,871 and 1,15~,123, U.~. Patent Nos. 2,679,498 and 3,050,502 and British Published Application No. 712,606.
Negative-working, mixed condensation products of aromatic diazonium compounds, for example according to German Offenlegungsschrift No. 2~024,244, which con-tain at least one unit each of the general types A(-D)n and B, linked by a divalent bridge member derived from a carbonyl compound capable of condensation. These symbols are nere defined as follows: A is the radical of a compound which contains at least two aromatic car-bocyclic and/or heterocyclic nuclei and which iscapable of condensation in an acid medium with an active carbonyl compound in at least one position.
is a diazonium salt group bonded to an aromatic carbon atom of A; n is an integer from 1 to 10 and B is the radical of a compound which is free of diazonium groups and which is capable of condensation in an acid madium with an active carbonyl compound in at least one posi-tion of the molecule.
Positive-working layers according to German Offenlegungsschrift No. 2,610,842, which contain a com-pound which eliminates acid on irradiation, a compound with at least one C-O-C group which can be eliminated by acid (for example an orthocarboxylic acid ester group or a carboxylic acid amide-acetal group) and, if appropriate, a binder.
Negative-working layers of photopolymerizable monomers, photoinitiators, binders and, if appropriate, further additives. The monomers used here are, for example, acrylates and methacrylates or reaction pro-ducts of diisocyanates with partial esters of poly-hydric alcohols, such as are desc~ibed, for example, in U.S. Patents No. ~,760,863 and No. 3,060,023 and in German Offenlegungsschriften No. 2,~64,079 and No. ~,361,041. Suitable photoinitiators are inter alia benzoin, benzoin ethers, polynuclear quinones, acridine derivatives, phenazine derivatives, quinoxaline deriva-tives, quinazoline derivatives or synergistic mixtures of different ketones. A large variety of soluble orga-nic polymers can be used as the binders, for example polyamides, polyesters, alkyd resins, polyvinyl alco-hol, polyvinylpyrrolidone, polyethylene oxide, gelatine or cellulose ethers.
Negative-working layers according to German Offenlegungsschrift No. 3,036,077 which contain, as the light-sensitive compund, a diazonium salt polyconden-sation product or an organic azido compound and, as the binder, a high-molecular polymer with alkenylsulfonyl-or cycloalkenylsulfonyl-urethane side groups.
Photo-semiconducting layers~ such as are described, for example, in German Patents ~o. 1,117,391, No. 1,522,497, No. 1,572,312, ~o. 2,32~,046 and No. 2,322,047~ can also be applied to the support materials, whereby highly light-sensitive electropho-tographic layers are produced.
The coated offset printing plates obtained from the support materials according to the invention are converted into the desired printing form in the known manner by imagewise exposure or irradiation and washing out of the non-image areas with a developer, preferably an aqueous developer solution. Sur-prisingly, offset printing plates, the base supportmaterials of which were treated according to the inven-)7 tion, are distinguished from those plates which for comparison were treated with a homopolymeric acryla-mide, with polymeric vinylphosphonic acid or only with hot wa-ter, by a markedly lower dye stain and an improved hydrophilic character. The adhesion of the light-sensitive layer to the surface of the support was also better in the samples treated according to the invention than in the comparison samples.

~2~)07 Examples _ of the preparation of a ~ ed and ano-dized printin~ ~ te support Al: Bright-rolled aluminum strip (DIN material No.
3.0255) of 0.3 mm thickness was degreased with an aqueous alkaline 2~ pickling solution at an elevated temperature of about 50 to 70C. The electrochemical roughening of the aluminum surface ~as effected with alternating current and in an electrolyte containing HNO3. This gave a surface roughness with an Rz value of 6 /um. The subsequent anodic oxidation was carried out according to the process described in German Offenlegungsschrift No. 2,811,396 in an electrolyte containing sulEuric acid. The oxid~ weight was about 3.0 g/m2. A support prepared in this way is marked by the number 1 in Tables 2 and 3O
The aluminum strip prepared in the above manner was then passed through a warm bath (60C~ of a 0.5% solution which contained one o~ the polymers according to the invention or one of the comparison substances (Nl to NV13).
The compositions of these solutions are listed in Table 1. The residence time in the bath was 30 seconds. In a rinsing step, the excess-solution was then removed with tap water and the strip was dried with hot air at tem-peratures between 100 and 130C.
A2: Bright-rolled aluminum strip (DIN material No.
3.0515) of 0.3 mm thickness was degreased with an aqueous alkaline 2% pickling solution at an elevated temperature of about 50 to 70C.
Electrochemical roughening of the aluminum surface was effected with alternating current ~2~
and in an electrolyte containing hydrochloric acid. This gave a surface roughness with an Rz value of 6 /um. The subsequent anodic oxi-dation was carried out in accordance with the process described in German Ofenlegungs-schrift No. 2,811,396, and in an electrolyte containing sulfuric acid. The oxide weight was about 3,0 g/m2.
A support prepared in this way is marked by the number 2 in Tables 2 and 3.
The aluminum strip thus prepared was then passed through a warm bath ~5GC) of a 0.5%
solution which contained one of the ~olymers according to the invention or one of the co~-parison substances (Nl to NV13). The com-posltions of these solutions are listed in Table 1.
y A3: Bright-rolled aluminum strip (DIN material No.
3.0255) of 0.2 mm thickness was degreased with ~o an aqueous-alkaline 2~ pickling solution at an elevated temperature of about 50 to 70~C. The support was then brushed, using cutting graining agents. This gave a surface rough-ness with an Rz value of 4 /um. The sub-sequent anodic oxidation was carried out according to U.S. Patent No. 3,511,661 in an electrolyte containing phosphoric acid. The oxide weight was 0.9 g/m2.

The aluminum strip thus treated was cut into sheets of 50 x 45 cm size.
A support prepared in this way is marked by the number 3 in Tables 2 and 3.

0~

The sup~orts thus prepared ~ere dipped into a warm bath (60C) of an aqueous solution of O.4~ of one of the polymers listed under Nl to NV13 in Table 1. The residence time in the bath was 60 seconds. The excess solution was then removed in a rinsing s-tep with deionized water and the support was dried in air.
Example B of the ~reparation of the reaction products (polymer/metal complexes) 0 2 mol, relative to one phosphonic acid unit, of the polymer listed under N3 in Table 1 was dissolved in 600 ml of water. 0.2 mol of Co(NO3)2 dissolved in 200 ml of water was then slowly added dropwise to this solution. After the addition had ended, the mixture was stirred for one additional hour. The reaction solution was then neutralized by slowly adding dilute aqueous NaOH solution. While doing this, the cobalt complex ~as deposited quantitatively as a viscous, rubber-likeviolet-colored precipitate. This precipitate was filtered off, washed with water and then with methanol and dried at 60C in a drying oven. The excess Co2+ ions remained in the filtrate. The polymers could also be reacted in the same way with other 9 at least divalent metal cations.

~able 1 -1 ? 3 No. Composition Monomer ratio N1 p-AMIP*/AM** 1:99 N3 " 10:90 10 N~ " 50:50 N5 " 70:30 N6 p-AMIP* 100: 0 N7 p-AMIP/AM-Ca*** 3:97 15 N8 p-AMIP/AM-Sr*** 10:90 N9 p-AMIP/AM-Co*** 10:90 N10 p-AMIP/AM-Mg**~ 1:99 NV11 ~ater 20 NV12 p-YPS

The meanings of the abbrev;ations are: -25 ~ acrylam;do;sobutyle-nephosphonic ac;d ** acrylamide *** metal salts (Ca, Sr, Mg or Co~ of the copolymeric acid~ prepared according to Example 8 P poly~er ~ - . . ' ~ . , 0~

The support materials described under Al to ~3, which were each treated with 13 different solu-tions, gave a total of 39 post-treated supports. The~
are listed in Table 2 r together with the measurement results explained below.
In addition to the dipping treatment described under Al and A3, some supports were subjected to an electrochemical post-treatment, which is described below.
Example C of electrochemical treatment Supports from Example A2 were dipped at 40C
into a 0.2~ solution of the products Nl to NV12 (Table 1). The supports were connected as the anode and treated for 20 seconds with direct current at 10 V.
During this treatment, the current fell from initially 3 A/dm2 to 0.2 A/dm2. Subsequently, the excess solu-tion was removed in a rinsing step with deionized water, and the supports were dried in air. The sup-ports thus prepared and the results of the measurements described below are listed in Table 3.
The following measurements were carried out on each of the support materials obtained according to the examples:
Testing of the alkali resistance of the surface (according to U.S. Patent No. 3,940,321, columns 3 and 4, lines 29 to 68 and lines 1 to 8):
The measure of the alkali resistance of an aluminum oxide layer is the rate of dissolution of the layer in seconds in an alkaline zincate solution. The layer is the more alkali-resistant, the longer it takes to dissolve it. The layer thicknesses should be approximately comparable, since tbey naturally also represent a parameter for the rate of dissolution. A
drop of a solution of 500 ml of distilled H2O, 480 g of KOH and 80 g oE zinc oxide is applied to the surface to be investigated and the time to the appearance of metallic zinc is determined, which manifests itself by a black coloration of the investigated spot. This "zincate ~est" is mentioned in column 4 of Table 2.
Testing of the hydrophilic character of the support materials prepared according to the invention The test is carried out by means of measure-ments of the angle of contact with a water drop placed on topO In this ~est, the angle between the support surface and a tangent going through the point of con-tact of the drop is measured. The angle is in general between 0 and 90. The wetting is the better, the smaller the angle. The data in column 5 of Table 2 relate to these contact angle measurements.
Examples D of coating of the supports with light-sensitive materials Dl: A piece of each of the supports described in the support examples Al to ~3 was coated with the following solution:
6.6 p.b.w. of a cresol/formaldehyde novolac (having a softening range of 105 - 120C
according to DIN 53 181) 25 1.1 p.b.w. of 4-(2-phenyl-prop-2-yl)-phenyl naphtho 1,2-quinone-2-diazide~4-sulfonate, 0.6 p~b~wo of 2 r 2'-bis-(naphtho-1,2-quinone-2-diazide-5-sulfonyl-oxy)-l,l'-dinaphthylmethane, 0.24 p.b.w. of naphtho-1,2-quinone-2-di-azide-4-sulfochloride, 0.08 p.b.w. of crystal violet and 91.36 p.b.w. of a solvent mixture of 4 ~2~3[)7 parts by volume of ethylene glycol monomethyl ether, 5 parts by volume of tetra-hydrofuran and 1 part by volume of butyl acetate.
The coatad supports were dried in a drying tunnel at temperatures of up to 120C. The printing plates thus prepared were exposed under a positive original and developed with a developer of the following composition:

5.3 p.b.w. of sodium metasilicate x 9 3.4 p.b.w. of trisodium phosphate x 12 15 0.3 p.b.w. of sodium dihydrogen phosphate (anhydrous) and 91.0 p~b.w. of water.
The printing forms obtained were visually assessed for any dye residues (blue stain) still pre-sent in the non-image areas. The result is given in column 6 of Table 2.
D2: A piece of each of the supports described in the support examples Al to A3 was provided with the following negative-working light sensitive layer:
16.75 p.b.w. of an 8% solution of the reaction product of a polyvi-nyl butyral, having a molecu-lar weight of 70,000 to 80,000 and composed of 71% by weight of vinyl butyral, 2%
of vinyl acetate and 27~ by weight of vinyl alcohol units, with propenylsulfonyl isocyanate, 2.14 p.b.w. of 2,6-bis-t4-azido-benzal)-4-methylcyclohexanone, 0.23 p.b.w. of Rhodamin ~6 GDN extra and 0.21 p.b.w. of 2-benzoylmethylene-1-methyl-~ -naphthothiazoline in 100 p.b.v. of ethylene glycol monomethyl ether and 50 p.b.v. of tetrahydrofuran.
The supports were dried as described under 3.
The dry layer weight was 0.75 g/m2. The reproduction layer was exposed for 35 seconds under a negative original with a metal halide lamp of 5 kW
power. The exposed layer was developed by means of a deep-etch pad with a developer solution of the following composition:
5 p.b.w. of sodium lauryl-sulfate 1 p.b.w. of sodium metasilicate x 5 H20 and 94 p.b.v. of water.
The non-image areas of the printing forms obtained were visually assessed for any layer residues still present. The result bf this assessment as com-pared with the state of the art ~NV12) is to be found in column 7 of Table 2.
The meanings of the symbols in Table 2 are - poorer than the state of the art of the comparison example of solution NV12 o equally good as the state of tbe art of the comparison example of solution NV12 + better than the state of the art of the comparison example of the solution NV12.

~2~ 07 D3: To prepare an electrophotographically working offset printing plate, an anodically oxidized support prepared according to Example 15 of Table 2 was coated with the Eollowing solu-tion:
p.b.w. of 2,5~bis-(4'-diethylamino-phenyl)-1,3,4-oxadiazole, p.b.w. of a copolymer of styrene and maleic anhydride, having a softening point of 210C, 0.02 p.b.w. Rhoclamin ~FB (C.I. 45 170) and 300 p.b.w. of ethylene glycol monomethyl ether The supports were dried as described under 3.
The layer was negatively charged in the dark to about 400 V by means of a corona. The charged plate was exposed imagewise in a process camera and then developed with an electrophotographic suspension deve-loper which represented a dispersion of 3.0 parts byweight of magnesium sulfate in a solution of 7.5 parts by weight of a pentaerythritol resin ester in 1200 parts by volume of an isoparaffin mixture having a boiling range from 185 to 210C. After removal of the excess developer liquid, the developer was fixed and the plate was dipped for 60 seconds into a solution of p.b.w. of sodium metasilicate x 9 H2O, 140 p.b.v. of glycerol, 550 p.b.v. of ethylene glycol and 140 p.b.v. of ethanol.
The plate was then rinsed with a vigorous jet of water, those areas of the photoconductor layer which are not covered with toner being removed. The plate was then ready for printing. The non-image areas of ~2~0~7 the plate showed a good hydrophilic character and indi-cated no signs of an attack even after the action of alXaline solutions. Several tens of thousands of good prints could be obtained with the printing form.

Tc~ble ~ 007 . ~
ample ¦ Sup- POst-treat-lzincate testj Cor,tact¦Color stail Y
No, ¦ port Iment a~ent I time/sec. ¦ angle 2 ¦ ~ ¦ N2 6 ¦ ~ ~ N6 ¦ o I ~ t a ¦ ~ ¦ 3 ¦ o ~ ¦ o 10 ~ N10 O + I o Vll .~ NVll o _ _ ¦ _ Vl ~ ,W 12 o o o I o V13 _ ~V13 - . _ 14 ¦ 2 Nl o ¦ +
. N2 O O +
16 ._ ._ . _ . _ ......... +
17 ~ . N4 o + + +
18 . N5 o + + +
19 ~ N6 o + + 0 ._ ~ N7 o + + +
21 . N8 o ~ + o 22 ~ N9 o + + o _ . .
23 ~ N10 OI o + o V24 ~ NVll o V25 ~ NV12 o ¦ o ¦ o I o V26 . NV13 ~
27 .1 3 ¦ Nl ¦ + ¦ + ¦ + ¦ +
28 1 ~ ¦ N2 1 + ¦ + ¦ + ¦ +
29 1 . ¦ N3 ¦ + ¦ + ¦ + ¦ +
. ~
30 ~ N4 ¦ o ¦ + ¦ + ¦ +
31 1 ~ I NS I o I + I + l +
32 1 ~ ¦ N6 ¦ o ¦ + ¦ ~ ¦ 0 I ~ r-- -- .
33 ~ o I + I t I O
34 1 ~ I N8 j o ¦ + I ~ j o 35 ¦ ~ ¦ N9 ~ o l l ¦ + ¦ o . . , 36 ¦ ~ ¦ N10 ¦ O ¦ + ¦ + ¦ o V37 1 ~ I NVll ¦ o l _ l _ l _ V38 1 ~ ¦ NV12 1 0 I O ¦ o I o V39 .¦ ~ ¦ NV13 ¦
--- --- - - 1 __. - . ! I
1) for po~itive la~ers 2)~ for r!egati~re layers ., . _ ~L2~1007 Table 2 proves that the products according to the invention are in many properties better than those of the state of the art, but not poorer in any of them.

12~07 ~able 3 Ex- Sup- Po~st- Zincate Con- Color Layer ample port treatment test tact stain residue No. . agent time ansle 1)~ 2)*
(sec) 2 N1 + + + +
41 2 N2 + + + +
42 2 N3 + + +

43 2 N4 + O + +
44 2 N5 + o ~ ~
2 N6 + o + o 46 2 ~7 + o +
47 2 N8 + O + +
48 2 N9 + O + +

49 2 N10 + O + O

51 2 NV12 o o o o 1)* for positive layers 2)* for negative ~ayers Table 3 shows that correspondi.ngly good values as in Table 2 were obtained for the electrochemically post-treated supports, and in particular the values for t'ne zincate test were further improved.
In addition to the tests described above, which were carried out with all the supports, supports prepared according to Examples 1 to 3 of Table 2 were also coated, as described under Dl, with a positive-working light-sensitive layer, and printing forms were prepared by exposure and development. With these, printing tests were carried out which gave up to 210,000 perfect prints. A printing form which was pre-pared analogously with a support from comparison example NV12 (Table 2) showed poorer roll-up behavior.
After 170,000 prints, fine halftone dots were no longer correctly reproduced.

Claims (6)

1. A support material for offset printing plates, comprising:
an aluminum-containing base material and a hydrophilic coating applied to at least one side of said aluminum-containing base material,said hydrophilic coating comprising a phosphonic acid com-pound selected from the group consisting of a polymer of acrylamidoisobutylene phosphonic acid, a copolymer of acrylamide and acrylamidoisobutylene phosphonic acid, a salt of either of the above with an at least divalent metal cation, and combinations of any of the above.

2. The support material as claimed in Claim 1, wherein the acrylamide/acrylamidoisobutylene phosphonic acid monomer ratio of said copolymer and copolymer salt is from about 1:99 to about 99:1.

3. The support material as claimed in Claim 2, wherein said monomer ratio is from about 3:97 to about 90:10.

4. The support material as claimed in Claim 1, wherein said metal cation is selected from the group consisting of a V5+, Bi3+, Al3+, Fe3+, Zr4+, Sn4+, Ca2+, Ba2+, Sr2+, Ti3+, Co2+, Fe2+, Mn2+, Ni2+, Cu2+, Zn2+ and Mg2+ ion.

5. The support material as claimed in Claim 1, wherein said coating comprises a mixture of at least two of said polymer, copolymer, and salt.
5. The support material as claimed in Claim 1, wherein said aluminum-containing base material has been pickled.

7. The support material as claimed in Claim 1, wherein said aluminum-containing base material has been roughened.
8. The support material as claimed in Claim 1, wherein said aluminum-containing base material has been anodically oxidized.
9. The support material as claimed in Claim

6, wherein said aluminum-containing base material has a peak-to-valley height Rz of from about 3 to about 10 /um.
10. The support material as claimed in Claim 8, wherein the oxide layer of the aluminum is from about 0.3 to about 3.0 /um thick.
11. The support material as claimed in Claim 9, wherein the oxide layer of the aluminum is from about 0.3 to about 3.0 /um thick.
12. A process for the preparation of a sup-port material for offset printing plates, comprising:
coating an aluminum-containing base material with a phosphonic acid compound as defined in Claim 1, said phosphonic acid compound being in the form of an aqueous solution having a concentration of from about 0.2 to about 5.0% by weight; and drying said base material;
wherein said coating step is performed by dipping or electrochemical treatment.
13. A process as claimed in Claim 12, said process including one or both of the steps of pickling and anodically oxidizing said aluminum-containing base material prior to said coating step.
14. A process for the preparation of a sup-port material for offset printing plates, comprising:
coating an aluminum-containing base material with a phosphonic acid compound selected from the group con-sisting of the polymer and copolymer of Claim 1 and combinations thereof, said phosphonic acid compound being in the form of an aqueous solution having a con-centration of from about 0.01 to about 10.0% by weight;
treating the coated aluminum-containing base material with a salt solution having a concentration of from about 0.1% by weight to saturation, said salt con-taining a divalent metal ion selected from the group consisting of a V5+, Bi3+, Al3+, Fe3+, Zr4+, Sn4+, Ca2+, Ba2+, Sr2+, Ti3+, Co2+, Fe2+, Mn2+, Ni2+, Cu2+, Zn2+ and Mg2+ ion, thereby forming a coating of the salt of said phosphonic acid compound and drying said base material.
15. A process as claimed in Claim 14, wherein said salt solution is aqueous.
16. A process as claimed in Claim 14, wherein said coating step and said treating step include immersing said base material in baths of the respective coating and treating solutions.
17. A process as claimed in Claim 14, wherein said phosphonic acid compound solution has a con-centration of from about 0.1% to about 5% by weight, and said salt solution has a concentration of from about 0.5 to about 10% by weight.
18. A process as claimed in Claim 14, wherein said base material is rinsed after said treating step.
19. A process as claimed in Claim 14, wherein said drying step is performed at a temperature of from about 110 to about 130°C.
20. A process as claimed in Claim 14, wherein said process includes one or both of the steps of pickling and anodically oxidizing said aluminum-containing base material prior to said coating step.
21. An offset printing plate formed by coating the support material of Claim 1 with a light-sensitive material.