EP0162282B1 - Procédé de grainage électrochimique d'aluminium pour supports de plaques d'impression dans un électrolyte composite aqueux - Google Patents

Procédé de grainage électrochimique d'aluminium pour supports de plaques d'impression dans un électrolyte composite aqueux Download PDF

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Publication number
EP0162282B1
EP0162282B1 EP85104604A EP85104604A EP0162282B1 EP 0162282 B1 EP0162282 B1 EP 0162282B1 EP 85104604 A EP85104604 A EP 85104604A EP 85104604 A EP85104604 A EP 85104604A EP 0162282 B1 EP0162282 B1 EP 0162282B1
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EP
European Patent Office
Prior art keywords
acid
weight
und
aluminum
aqueous
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP85104604A
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German (de)
English (en)
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EP0162282A2 (fr
EP0162282A3 (en
Inventor
Dieter Dr. Dipl.-Chem. Mohr
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hoechst AG
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Hoechst AG
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Publication date
Application filed by Hoechst AG filed Critical Hoechst AG
Publication of EP0162282A2 publication Critical patent/EP0162282A2/fr
Publication of EP0162282A3 publication Critical patent/EP0162282A3/de
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Publication of EP0162282B1 publication Critical patent/EP0162282B1/fr
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
    • C25F3/00—Electrolytic etching or polishing
    • C25F3/02—Etching
    • C25F3/04—Etching of light metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM
    • B41N3/00—Preparing for use and conserving printing surfaces
    • B41N3/03—Chemical or electrical pretreatment
    • B41N3/034—Chemical or electrical pretreatment characterised by the electrochemical treatment of the aluminum support, e.g. anodisation, electro-graining; Sealing of the anodised layer; Treatment of the anodic layer with inorganic compounds; Colouring of the anodic layer

Definitions

  • the invention relates to a method for the electrochemical roughening of aluminum for printing plate supports, which is carried out with alternating current in an aqueous mixed electrolyte.
  • Printing plates generally consist of a support and at least one radiation-sensitive reproduction layer arranged thereon, this layer either from the consumer (in the case of non-precoated plates) or from the industrial one Manufacturer (for pre-coated boards) is applied to the substrate.
  • Aluminum or one of its alloys has established itself as a layer material in the printing plate field.
  • these substrates can also be used without a modifying pretreatment, but they are generally modified in or on the surface, for example by mechanical, chemical and / or electrochemical roughening (sometimes also called grain or etching in literature), chemical or electrochemical oxidation and / or treatment with hydrophilizing agents.
  • a combination of the above-mentioned types of modification is often used, in particular a combination of electrochemical roughening and anodic oxidation, possibly with a subsequent hydrophilization step.
  • the roughening is carried out, for example, in aqueous acids such as aqueous HCI or HN0 3 solutions, in aqueous salt solutions such as aqueous NaCl or Al (NO 3 ) 3 solutions or in combinations of these components using alternating current.
  • the roughness depths that can be achieved in this way are in the range from about 1 to 15 ⁇ m, in particular in the range from 2 to 8 ⁇ m.
  • the roughness depth is determined in accordance with DIN 4768 in the version from October 1970, the roughness depth R z is then the arithmetic mean of the individual roughness depths of five adjoining single measurement sections.
  • aqueous HCl solutions as an electrolyte solution for the electrochemical roughening of support materials made of aluminum must therefore be assumed to be known. It can be obtained - as many examples of commercial printing plates show - a uniform grain size, which is particularly suitable for the field of application of lithography and is within a roughness range that is generally useful in practice. For certain areas of application of printing plates (e.g.
  • the previously known organic additives to aqueous acid electrolytes such as HCI or HN0 3 solutions have the disadvantage that they become electrochemically unstable and at least partially decompose at high current loads (voltage) in modern continuously operating conveyor systems.
  • the known inorganic additives such as phosphoric, chromic or boric acid have the disadvantage that the intended protective effect frequently breaks down locally and individual, particularly pronounced scars then develop there. So z. B. the addition of H 3 PO 4 lead to flat roughened surfaces, but they have the disadvantage of many deep individual holes.
  • the additives known to have a complexing effect generally accelerate the dissolution of the aluminum by “capturing released Al 3+ ions, and thereby increase the roughening attack; However, this often leads to the fact that no additional hole nuclei are created, but that already formed nuclei and holes continue to grow, ie there is then increased scar formation.
  • the previously known inhibitory additives generally have the effect that the hole growth of individual holes is stopped relatively soon and new hole nuclei can arise; However, they have the decisive disadvantage that this protective effect due to defects, alloy components and the like. ⁇ . can collapse; this then leads to deep holes in an otherwise flat and evenly roughened surface. Backing materials with such imperfections are unsuitable for lithographic purposes.
  • the object of the present invention is therefore to propose a method for the electrochemical roughening of aluminum for printing plate supports, which makes it possible to achieve a uniformly roughened surface topography with a wide range in the mean roughness depth values and to achieve long bath service lives.
  • the invention is based on the known process for the electrochemical roughening of aluminum or its alloys for printing plate supports in an aqueous mixed electrolyte solution containing HCl and at least one organic acid under the action of alternating current.
  • the process according to the invention is then characterized in that the organic acid is a compound from the group of diphosphonic acids, polyphosphonic acids and gallic acid.
  • the aqueous electrolyte solution contains 0.5 to 10.0%, in particular 0.8 to 5.0%, of HCl and 0.05 to 5.0%, in particular 0.1 to 2.0% of organic acid.
  • the phosphonic acids which can be used in the process according to the invention include, in particular, di- and polyphosphonic acids (ie compounds having at least 3 phosphonic acid groups) with aliphatic organic radicals, ie preferably alkane or polyphosphonic acids from C 1 to C 6 and with up to 6 phosphonic acid groups, which are optionally substituted may also have other functional groups such as hydroxyl or amino groups on the alkane moiety.
  • the phosphonic acid groups are preferably located as substitutes on carbon atoms, but they can also be linked to heteroatoms.
  • Gallic acid is 3,4,5-trihydroxy-benzoic acid.
  • Suitable base materials for the material to be roughened according to the invention include those made of aluminum or one of its alloys, which for example have a content of more than 98.5% by weight. Al and share of Si, Fe, Ti, Cu and Zn. These aluminum carrier materials can also be roughened mechanically (for example by brushing and / or with abrasive treatments) before the electrochemical stage, if appropriate after pre-cleaning. All process steps can be carried out discontinuously with plates or foils, but they are preferably carried out continuously with tapes.
  • the process parameters lie in the following ranges: the temperature of the electrolyte between 20 and 60 ° C., the current density between 3 and 200 A / dm 2 , the residence time of a material point to be roughened in the electrolyte between 1 and 300 sec and the electrolyte flow rate at the surface of the material to be roughened between 1 and 300 cm / sec; in the batchwise process, the required current densities tend to be in the lower part and the dwell times are in the upper part of the ranges specified, and the flow of the electrolyte can also be dispensed with.
  • alternating current with a frequency of 50 to 60 Hz is used as the current type, but there are also modified types of current such as alternating current with different amplitudes of the current strength for the anode and cathode current, lower frequencies, current interruptions or overlapping of two currents different. Frequency and waveform possible.
  • the average roughness depth R z of the roughened surface is in the range from 1 to 15 ⁇ m, in particular from 1.5 to 8.0 ⁇ m.
  • aluminum ions in the form of aluminum salts in particular 0.5 to 5.0% of AICI 3, can also be added to the aqueous electrolyte.
  • Pre-cleaning includes, for example, treatment with aqueous NaOH solution with or without degreasing agent and / or complexing agents, trichlorethylene, acetone, methanol or other commercially available aluminum stains.
  • the roughening or, in the case of several roughening stages, also between the individual stages, an abrasive treatment can additionally be carried out, in particular a maximum of 2 g / m 2 being removed (up to 5 g / m 2 between the stages);
  • aqueous solutions of alkali metal hydroxide or aqueous solutions of alkaline salts or aqueous acid solutions based on HN0 3 , H 2 SO 4 or H 3 PO 4 are used as abrasive solutions.
  • non-electrochemical treatments are also known which essentially have only a rinsing and / or cleaning effect and, for example, for removing deposits formed during roughening ("Schmant") or simply for Serve removal of electrolyte residues; For example, dilute aqueous alkali hydroxide solutions or water are used for these purposes.
  • an anodic oxidation of the aluminum can then preferably follow in a further process step to be used, for example in order to improve the abrasion and adhesion properties of the surface of the carrier material.
  • the usual electrolytes such as H 2 S0 4 , H 3 P0 4 , H 2 C 2 0 4 , amidosulfonic acid, sulfosuccinic acid, sulfosalicylic acid or mixtures thereof can be used for anodic oxidation; in particular, H 2 S0 4 and H 3 P0 4 are used alone, in a mixture and / or in a multi-stage anodizing process.
  • the stage of anodic oxidation of the aluminum support material can also be followed by one or more post-treatment stages.
  • These post-treatment stages serve in particular to additionally increase the hydrophilicity of the aluminum oxide layer, which is often sufficient, while at least the other known properties of this layer are retained.
  • the materials produced according to the invention are used as supports for offset printing plates, i. H. a radiation-sensitive coating is applied to one or both sides of the carrier material either by the manufacturer of presensitized printing plates or directly by the consumer.
  • a radiation-sensitive coating is applied to one or both sides of the carrier material either by the manufacturer of presensitized printing plates or directly by the consumer.
  • all layers are suitable as radiation (light) sensitive layers which, after irradiation (exposure), optionally with subsequent development and / or fixation, provide an image-like area from which printing can take place.
  • photoconductive layers such as z. B. in DE-C-1 117391, 1522497, 1572312, 2322046 and 2 322 047 are described, are applied to the carrier materials produced according to the invention, whereby highly light-sensitive, electrophotographic printing plates are formed.
  • coated offset printing plates obtained from the carrier materials produced by the process according to the invention are converted into the desired printing form in a known manner by imagewise exposure or irradiation and washing out of the non-image areas with a developer, for example an aqueous alkaline developer solution.
  • a developer for example an aqueous alkaline developer solution.
  • “scars” marked depressions compared to the roughening of the surroundings
  • the method also enables the formation of particularly flat and uniformly roughened surfaces, a combination of properties that cannot be achieved to this extent with the known electrolytes.
  • the mixed electrolyte in the process according to the invention is electrochemically stable, i.e. H. there is no decomposition at high current load (voltage).
  • % data always mean% by weight, unless stated otherwise, parts by weight are in parts by volume in the ratio of g to cm 3 .
  • An aluminum sheet is first pickled for 60 seconds in an aqueous solution of 20 g NaOH per liter at room temperature and then freed of any alkali residues that may be present by briefly immersing it in a solution corresponding to the roughening electrolyte.
  • the roughening takes place in the electrolyte systems shown in the following tables and under the conditions listed there.
  • an anodic oxidation is carried out in an aqueous electrolyte containing H 2 S0 4 and Al 3 + - ions up to a layer weight of 3.0 g / m 2 .
  • the classification into the quality classes is carried out by visual assessment under a microscope, whereby a homogeneously roughened and scar-free surface is assigned quality level «1» (best value).
  • Quality level “10” (worst value) is assigned to a surface with thick scars larger than 100 ⁇ m or an extremely unevenly roughened or almost rolled surface.
  • Intermediate qualities are rated “2" to "9”. All examples and the comparative examples are carried out with symmetrical alternating current at a frequency of 50 Hz, one electrode being the aluminum sheet and the other a graphite plate. (See continuation on page 7 f.)
  • the layer is negatively charged to about 400 V in the dark by means of a corona.
  • the charged plate is exposed imagewise in a repro camera and then with an electrophotographic suspension developer which comprises dispersing 3.0 parts by weight of magnesium sulfate in a solution of 7.5 parts by weight of pentaerythritol resin ester in 1200 parts by weight of an isoparaffin mixture a boiling range of 185 to 210 ° C was obtained.
  • the developer is fixed and the plate in a solution of 35 parts by weight of sodium metasilicate for 60 seconds.
  • 9 H 2 0, 140 parts by weight of glycerol, 550 parts by weight of ethylene glycol and 140 parts by weight of ethanol immersed.
  • the plate is then rinsed off with a powerful jet of water, removing the areas of the photoconductor layer not covered with toner.
  • the printing form is then ready for printing.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Printing Plates And Materials Therefor (AREA)

Claims (6)

1. Procédé pour le grainage électrochimique d'aluminium ou de ses alliages pour supports de plaques d'impression, dans une solution électrolytique aqueuse mixte contenant de HCI et au moins un acide organique, sous l'effet d'un courant alternatif, caractérisé en ce que l'acide organique est un composé choisi parmi des acides diphosphoniques, des acides polyphosphoniques et l'acide gallique.
2. Procédé selon la revendication 1, caractérisé en ce que l'électrolyte mixte contient de 0,5 à 10,0 % en poids de HCI et de 0,05 à 5,0 % en poids de l'acide organique.
3. Procédé selon la revendication 1 ou 2, caractérisé en ce que l'électrolyte mixte contient de 0,8 à 5,0 % en poids de HCI et de 0,1 à 2,0 % en poids de l'acide organique.
4. Procédé selon l'une des revendications 1 à 3, caractérisé en ce que les acides phosphoniques comportent 2 à 6 groupes phosphono, un fragment alcane en Ci à Ce et éventuellement des groupes hydroxy ou amino en tant qu'autres groupes fonctionnels.
5. Procédé selon l'une des revendications 1 à 4, caractérisé en ce que l'on utilise en tant qu'acides phosphoniques l'acide 1-hydroxy-éthane-1,1-diphosphonique et/ou l'acide amino-tris(méthylènephos- phonique).
6. Utilisation du procédé selon l'une des revendications 1 à 5, dans la fabrication de plaques d'impression offset portant une couche sensible aux radiations.
EP85104604A 1984-04-25 1985-04-16 Procédé de grainage électrochimique d'aluminium pour supports de plaques d'impression dans un électrolyte composite aqueux Expired EP0162282B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19843415363 DE3415363A1 (de) 1984-04-25 1984-04-25 Verfahren zur elektrochemischen aufrauhung von aluminium fuer druckplattentraeger in einem waessrigen mischelektrolyten
DE3415363 1984-04-25

Publications (3)

Publication Number Publication Date
EP0162282A2 EP0162282A2 (fr) 1985-11-27
EP0162282A3 EP0162282A3 (en) 1985-12-27
EP0162282B1 true EP0162282B1 (fr) 1987-08-19

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP85104604A Expired EP0162282B1 (fr) 1984-04-25 1985-04-16 Procédé de grainage électrochimique d'aluminium pour supports de plaques d'impression dans un électrolyte composite aqueux

Country Status (4)

Country Link
US (1) US4626328A (fr)
EP (1) EP0162282B1 (fr)
JP (1) JPS60234897A (fr)
DE (2) DE3415363A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0249650B1 (fr) * 1986-06-20 1989-12-13 Poligrat Gmbh Electrolyte pour le polissage électrochimique de surfaces de métaux
JPH01318079A (ja) * 1988-06-17 1989-12-22 Lion Corp エッチング剤
US5736256A (en) * 1995-05-31 1998-04-07 Howard A. Fromson Lithographic printing plate treated with organo-phosphonic acid chelating compounds and processes relating thereto

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS517081B1 (fr) * 1971-04-17 1976-03-04
GB1392191A (en) * 1971-07-09 1975-04-30 Alcan Res & Dev Process for electrograining aluminium
DE2250275A1 (de) * 1972-10-13 1974-04-25 Oce Van Der Grinten Nv Verfahren zur elektrochemischen behandlung von aluminium zur herstellung lithographischer druckplatten
US4052275A (en) * 1976-12-02 1977-10-04 Polychrome Corporation Process for electrolytic graining of aluminum sheet
GB1598701A (en) * 1977-04-16 1981-09-23 Vickers Ltd Electrolytic graining of aluminium or aluminium alloy surfaces
JPS56135095A (en) * 1980-03-26 1981-10-22 Mitsubishi Chem Ind Ltd Manufacture of supporter for planographic process block
JPS5724294A (en) * 1980-07-18 1982-02-08 Mitsubishi Chem Ind Ltd Production of support for planographic printing plate
EP0050216B1 (fr) * 1980-09-26 1985-01-09 American Hoechst Corporation Procédé pour l'oxydation anodique d'aluminium et son utilisation comme support pour planches d'imprimerie
US4414311A (en) * 1982-03-18 1983-11-08 American Hoechst Corporation Cathodic deposition of light sensitive components

Also Published As

Publication number Publication date
DE3560490D1 (en) 1987-09-24
EP0162282A2 (fr) 1985-11-27
EP0162282A3 (en) 1985-12-27
US4626328A (en) 1986-12-02
DE3415363A1 (de) 1985-10-31
JPS60234897A (ja) 1985-11-21

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