Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
  • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
  • G03G5/14—Inert intermediate or cover layers for charge-receiving layers
  • G03G5/142—Inert intermediate layers

Definitions

• the invention relates to a process for the production of electrophotographic recording elements from pretreated aluminum supports and photoconductive layers, an intermediate layer being applied between the support and the photoconductive layer, and to the use of these electrophotographic recording elements for electrophotographic offset printing, in particular those using aqueous, alcoholic or aqueous / alkaline solutions can be developed.
• the photoconductor layer applied to the electrically conductive substrate is charged, exposed imagewise, developed with liquid or dry toner to form an image, the toner image is fixed by heating, and the printing plate is removed by removing the unstressed one Developed photoconductor layer.
• the offset printing form obtained takes on ink at the toner image areas and water at the exposed areas of the carrier surface.
• a substrate which is to be suitable for light-sensitive material for the production of a printing plate has to satisfy two criteria.
• the printing image areas developed from the copying layer of the material must adhere very firmly to it
• the support must represent a sufficiently hydrophilic image background so that it retains its repellent effect against oleophilic printing inks under the diverse requirements of the printing process. The latter is brought about by a porous surface structure, so that the surface of the support retains enough water to be sufficiently repellent to oleophilic printing inks.
• Aluminum and aluminum alloys are mainly used for offset printing plates, which are modified by a series of pretreatment steps in order to ensure good adhesion of the radiation-sensitive layer and thus long print runs.
• aluminum is roughened mechanically, chemically and / or electrochemically, if necessary pickled and anodized.
• the standard pretreatment methods include electrochemical roughening in HCl and / or HNO3 and anodic oxidation in H2SO4 and / or H3PO4.
• PVPS polyvinylphosphonic acid
• Carrier materials treated with PVPS also tend to show signs of aging when stored uncoated. These manifest themselves in decreasing hydrophilicity as well as in the reduced developability of negatively working light-sensitive layers, which are coated only a long time after the carrier has been produced.
• the object of the invention was to provide a class of compound which, as an intermediate layer between the support and the photoconductive layer, increases the hydrophilicity of the non-image areas without negatively influencing the adhesion of the radiation-sensitive layer to the support material, and thus avoids the aforementioned disadvantages of known treatment agents.
• silanes are also used as adhesion promoters in so-called dry offset printing plates.
• the "dry" planographic printing plate is based on the principle of ensuring a differentiation between printing and non-printing parts by means of an ink-accepting, light-sensitive polymer layer and an oleophobic, oily ink-repellent and thus non-printing silicone rubber layer. For this purpose e.g.
• a photosensitive polymer layer is applied to a silicone rubber layer on a metal support, imagewise exposed and developed, so that e.g. in the case of a negative-working plate, the silicone rubber layer is exposed at the unexposed areas, while the polymer layer which is hardened by actinic radiation and is insoluble in the developer is formed on the exposed areas.
• a silane coupling agent is used which acts as an adhesive contact between the carrier and the silicone rubber (see e.g. DE-PS 23 57 871 and DE-PS 23 23 453).
• the invention relates to a method for producing an electrophotographic recording element from a mechanically, chemically and / or electrochemically pretreated and anodically oxidized aluminum support and a photoconductive layer which is applied to this support, which is characterized in that between the support and the photoconductive Layer is applied a thin hydrophilizing layer of a hydrolyzate or condensate of at least one silane.
• silanes to be used in hydrolyzed or condensed form for the process according to the invention are silanes of the general formula (I) X- (CH2) y -Si (R1) n (OR2) 3-n (I) wherein R1 and R2 are the same or different from each other and represent alkyl radicals having 1 to 9 carbon atoms or aryl radicals having 6 to 12 carbon atoms and X for one of the residues stands for R3 for hydrogen, an alkyl radical with 1 to 9 carbon atoms, a carboxylic acid radical with 1 to 9 carbon atoms or one of this carboxylic acid radical and that bound to R3 HO ⁇ - H ⁇ rest formed carboxylic acid anhydride ring, R4 and R5 are identical or different from one another and represent an alkyl radical with 1 to 9 carbon atoms or an aryl radical with 6 to 12 carbon atoms, R6 represents hydrogen, an alkyl radical with 1 to 9 carbon atoms or an aryl radical with
• silanes of the formulas given above are used in hydrolyzed or condensed form.
• the hydrolyzate or condensate of the silane is generally applied in the form of its solution to the pretreated aluminum support by customary application methods, such as spraying or dipping, any excess is removed and the coated support is dried at 50 to 120 ° C.
• the present invention also relates to electrophotographic recording elements which have been produced by the process according to the invention and to their use for the electrophotographic production of offset printing plates.
• the hydrolyzate or condensate of the silane is expediently used in an aqueous or alcoholic solution.
• These solutions generally contain the hydrolyzate or condensate of the silane in amounts of 0.05 to 30, preferably 0.1 to 10, in particular 0.5 to 3% by weight. They can be prepared in an unusual manner by, if appropriate acid-catalyzed, hydrolysis from the underlying silanes of the general formula (I).
• the application of these solutions to the mechanically, chemically and / or electrochemically pretreated aluminum support in a thin layer can be carried out by customary application methods, preferably by spraying or in particular by immersing the support in the aqueous solution at temperatures between 15 and 85 ° C, preferably at 25 to 60 ° C, for example during a period of 0.5 to 120, preferably 10 to 60 seconds.
• Excess solution can then be removed by rinsing or rinsing with water or alcohol, and the supports treated in this way can be dried at temperatures between 20 and 120 ° C., preferably 50 and 110 ° C.
• silanes of the general formula (I) are particularly suitable for the process according to the invention X- (CH2) y -Si (R1) n (OR2) 3-n (I) in which R 1 and R 2 are identical or different from one another and for alkyl radicals having 1 to 9, preferably 1 to 4 carbon atoms, such as, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl radicals or for aryl radicals having 6 to 12 carbon atoms, such as phenyl, benzyl or methylphenyl and X for one of the residues R3 is hydrogen, an alkyl radical with 1 to 9 carbon atoms, preferably 1 to 4 carbon atoms, for example methyl, ethyl, propyl or butyl radicals, a carboxylic acid radical with 1 to 9, preferably 1 to 4 carbon atoms, for example -COOH, -CH2COOH, -C2H4CO
• silanes are (2-tripropoxysilylethyl) carboxylic acid, (3-trimethoxysilylpropyl) carboxylic acid, (4-trimethoxysilylbutyl) carboxylic acid and its methyl, ethyl, propyl and butyl esters, (3-triethoxysilylpropyl) succinic anhydride), (3-triethoxy) maleic anhydride, (2-trimethoxysilylethyl) phosphonic acid dimethylester, (3-triethoxysilylpropyl) phosphonic acid dimethyl ester and -phosphonic acid diethyl ester, (2-trimethoxysilylmethyl) phosphonic acid dichloride, (3-trimethoxysilylpropyl) phosphylulfonic acid (2) - (4-Sulfonylphenyl) ethyltrimethoxysilane, (3-trimethoxysilylpropyl) sulf
• hydrolysis of such silanes can be carried out in the usual way in water or aqueous solutions of alcohols, if appropriate in the presence of acids.
• condensates can also form during hydrolysis.
• hydrolyzates and condensates as well as mixtures of hydrolyzates and condensates of the abovementioned silanes are suitable for the process according to the invention, as long as it is ensured that the hydrolysates or condensates are completely dissolved in the aqueous or alcoholic solution.
• the aluminum supports to be used for the method according to the invention are pretreated mechanically, chemically and / or electrochemically in the usual way and anodically oxidized.
• Such pretreatment methods are described for example in Wernick, Pinner, Zurbrugg, Weiner, "The surface treatment of aluminum”, Eugen G. Leuze Verlag, 1977.
• the post-treated aluminum support After the treatment of the pretreated aluminum support according to the invention with the solution of the hydrolyzate or condensate of the silane and drying of the thin layer, the post-treated aluminum support is provided in the usual way with the photoconductive layer.
• This photoconductive layer can be constructed from a single-layer or from a two-layer system.
• Suitable single-layer systems preferably have a layer (B) of (a) 65 to 35% by weight of at least one organic binder, (b) 30 to 60, in particular 38 to 46% by weight, of a conductive support material (A) treated with silane hydrolyzate according to the invention Mixture of the compounds which transport charge carriers and (c) 0.02 to 2.5% by weight of a compound which generates charge carriers upon actinic exposure, in particular a suitable dye.
• the layers are advantageously applied from an approximately 6% by weight solution in a suitable organic solvent to the carrier material treated according to the invention in such a way that, after the solvent has been flashed off, a dry layer thickness of approximately 0.8 to 40 ⁇ m, depending on the intended use electrophotographic printing forms, in particular 0.8 to 6 microns, results.
• Suitable multilayer systems have, for example, on the conductive carrier material (A) treated according to the invention with silane hydrolyzate, e.g. ( ⁇ ) a charge carrier-generating layer and ( ⁇ ) a charge transport layer composed of 30 to 60% by weight of the mixture of the compounds which transport the charge carriers, 65 to 35% by weight of an organic binder and optionally up to 15% by weight of further the mechanical properties of the Layer-improving additives.
• the first layer is advantageously applied to the carrier material in a thickness of 0.005 to 5 ⁇ m, in particular 0.1 to 0.9 ⁇ m, as a solution in a suitable solvent.
• the second layer is applied in a thickness that results in a layer thickness of 5 to 25, in particular 7 to 15 ⁇ m, after drying the composite structure.
• suitable organic binders (a) for the layers depends on the intended use of the recording materials.
• Cellulose ethers, polyester resins, polyvinyl chlorides, polycarbonates, copolymers such as styrene-maleic anhydride copolymers or vinyl chloride-maleic anhydride copolymers or mixtures of such binders are suitable for the copying sector.
• their film-forming and electrical play Properties, their adhesive strength on the carrier material and their solubility properties play a special role.
• those which are soluble in basic, aqueous or alcoholic solvents are particularly suitable.
• binders especially those with high acid numbers, which are readily soluble in basic aqueous-alcoholic solvent systems and have an average molecular weight (weight average) of 800 to 80,000 and in particular 1,500 to 50,000.
• Suitable are, for example, copolymers of methacrylic acid and methacrylic acid esters, particularly copolymers of styrene and maleic anhydride and of styrene, methacrylic acid and methacrylic acid esters, provided they have the above solubility conditions.
• copolymers of styrene, maleic anhydride and acrylic or methacrylic acid which have a copolymerized maleic anhydride content of 5 to 50% by weight and a copolymerized acrylic or methacrylic acid content of 5 to 35, in particular 10 to 30,%. % have satisfactory electrophotographic layers with sufficiently low dark conductivity. They have excellent solubility in detergents made from 75% by weight of water, 23% by weight of isobutanol and 2% by weight of soda, but are insoluble in offset-typical wiping water.
• Suitable charge carrier transporting compounds (b) which are contained in this layer are compounds which do not impair transparency for visible light, such as low molecular weight compounds, in particular heterocyclic compounds such as pyrazoline derivatives, oxazoles, oxadiazoles, phenylhydrazones, imidazoles, triphenylamine derivatives, carbazole derivatives, Pyrene derivatives and other condensed aromatics, as well as compounds such as those mentioned in EP application no. 86105253.8, as well as polymeric materials such as polyvinylpyrene, poly (N-vinylcarbazole), copolymers of carbazole and styrene, or vinyl acetate and / or Vinyl chloride. Of the polymeric type, poly- (N-vinylcarbazole) is particularly suitable.
• Suitable compounds which generate charge carriers under actinic exposure, (c) or sensitizers are e.g. for systems applied in one layer, such as those used for the production of electrophotographic printing forms, dyes from the triarylmethane series, xanthene dyes and cyanine dyes. Very good results have been e.g. with rhodamine B (C.I. 45170), rhodamine 6 G (C.I. 45160), malachite green (C.I. Basic Green 4; C.I. 4200), methyl violet (C.I. 42535) or crystal violet (C.I: 42555).
• the dye or pigment is present in a separate layer which generates charge carriers.
• Azo dyes, phthalocyanines, isoindoline dyes and perylene tetracarboxylic acid derivatives are effective here. Particularly good results are achieved with perylene-3,4: 9,10-tetracarbonic acid diimide derivatives, as described in DE-OS 31 10 954 and DE-OS 31 10 960.
• the electrophotographic recording material can contain conventional additives, e.g. Leveling agent and plasticizer in the photoconductive layer or adhesion promoter between carrier and layer.
• electrophotographic offset printing forms are produced by electrostatically charging the electrophotographic recording material using a high-voltage corona, immediately following image-wise exposure, developing the electrostatic latent charge image present using a dry or liquid toner, fixing the toner by means of a subsequent melting process and removing it the unstressed, photoconductive layer by means of a suitable washout solvent.
• the printing form thus obtained can also be prepared for offset printing in a known manner, e.g. through a rubber coating on the water-bearing surface.
• the ratings refer to the non-printing areas of the printing form.
• An electrochemically roughened by AC treatment in aqueous HCl and HNO3 solution and anodized in sulfuric acid oxidized aluminum sheet is coated with a 10% solution of an electrophotographic recording material in tetrahydrofuran so that the layer weight after drying (30 minutes at 80 ° C) 4 g / m2.
• the electrophotographic recording material used for this has the following composition: 54.6% of a copolymer of styrene and methacrylic acid (weight ratio 2: 1) 45% 2,5-bis (4 ⁇ -diethylaminophenyl) oxadiazole-1,3,4 0.4% CI Basis Red 1; CI No. 45160
• the layer is then loaded with a corona at a distance of 10 mm and an associated high-voltage source of 6.75 kV to a surface potential of -850 V and exposed in a repro camera with 4 halogen lamps of 1000 W each for 15 seconds using a test template.
• the aluminum foil with the concrete-coated photoconductor layer is placed in a cuvette and developed with the aid of a commercially available aqueous-alkaline developer.
• the printing plate thus produced is colored with printing ink.
• An electrochemically roughened by alternating current treatment in aqueous HCl and HNO3 solution and anodically oxidized in phosphoric acid serves as a support for a printing plate produced according to Comparative Example 1.
• a 3% aqueous solution of the corresponding silane hydrolyzate is prepared by hydrolysis of (3-triethoxysilylpropyl) succinic anhydride in water.
• a printing plate aftertreated and coated in accordance with Example 1 is stored at 50 ° C. for 30 days and then processed in the usual manner.
• Example 2 The procedure is as described in Example 1, with the change that, as described in Comparative Example 2, it is an aluminum sheet anodized in phosphoric acid.
• a printing plate aftertreated and coated in accordance with Example 1 is stored at 50 ° C. for 30 days and then processed in the usual manner.
• An aluminum sheet anodized in sulfuric acid as described in Comparative Example 1 is processed according to Example 1 with the difference that the temperature of the 3% silane hydrolyzate solution is 25 ° C.
• a printing plate produced according to Example 5 is first stored at 50 ° C. for 30 days and then processed in the usual way.
• a printing plate produced according to Example 7 is first stored at 50 ° C. for 30 days and then processed in the usual way.
• the printing plate produced in this way delivered 100,000 flawless prints on a newspaper rotary printing press (COLORMAN) despite several interruptions and drying of the printing plate.
• a printing plate produced according to Example 9 is first stored at 50 ° C. for 30 days and then processed in the usual way.
• An aluminum sheet anodized in phosphoric acid as described in Comparative Example 2 is processed according to Example 1 with the difference that the aftertreatment is carried out by immersion in a 1% silane hydrolyzate solution at 25 ° C.
• a printing plate produced according to Example 10 is first stored at 50 ° C. for 30 days and then processed in the usual way.

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• 1986
  • 1986-08-16 DE DE19863627758 patent/DE3627758A1/de not_active Withdrawn
• 1987
  • 1987-06-22 US US07/064,538 patent/US4782000A/en not_active Expired - Fee Related
  • 1987-06-24 EP EP87109053A patent/EP0256255A3/fr not_active Withdrawn
  • 1987-08-14 JP JP62201969A patent/JPS6350855A/ja active Pending

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