JPH0251732B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves irradiating an aluminum support coated with a recording layer containing a diazo compound with a laser beam according to the image line, thereby producing lipophilic or insoluble image areas in the recording layer. Concerning the manufacturing method of solid lithographic printing plates.

US Pat. No. 3,664,737 describes printing plates which have a UV-sensitive layer, preferably a diazo layer, on an aluminum support and which are irradiated with laser light.

German Patent Application No. 2 448 325 and German Patent Application No. 2 543 820 describe a method for producing a printing plate by irradiating a non-photosensitive recording layer with a laser. Permanently lipophilic, or if the layer is already lipophilic, consists in rendering it insoluble in a suitable developer. Supporting materials include, inter alia, anodized aluminum.

Furthermore, West German Patent Application No. P 2725308 discloses that a presensitized printing plate having a support made of optionally anodized aluminum and a photosensitive layer containing a negative diazo compound is imaged with laser light. A method has been proposed.

Furthermore, West German Patent Application No. P 2725307 proposes a method of sensitizing printing plates of the above type to laser irradiation in the visible light range by adding a sensitizing dye to the photosensitive layer. ing.

The purpose of the original invention (Japanese Patent Publication No. 61-48418) is to
a layer support made of anodized aluminum;
A recording material having a recording layer on an oxide layer is irradiated with a laser beam according to the image line, thereby rendering the irradiated areas of the recording layer lipophilic and/or insoluble, and then optionally making the non-irradiated recording layer areas oleophilic and/or insoluble. A method for producing lithographic printing plates, which is washed off with a developer, is characterized in that the method uses a layer support having an oxide layer with a layer weight of at least 3 g/m ² .

The object of the invention was to further improve the method of the original invention.

The invention starts from the original inventive method. The method of the present invention is characterized by using a water-soluble salt of a negative photocurable diazonium condensation product and an anion.

Negative photocurable diazonium condensation products suitable for use in the process of the invention are in particular water-soluble salts with the anion of diazonium condensation products, also referred to as diazo resins. Suitable diazonium condensation products are obtained by condensation of aromatic diazonium salts, optionally substituted diphenylamine-4-diazonium salts, with active carbonyl compounds, preferably formaldehyde, in a strongly acidic medium. Products of this type are described, for example, in German patent no. 1214086 and in German patent no.
It is described in the specification of No. 1292001. Examples of these water-soluble salts include tetrachlorozincate, methanesulfonate, or hydrogenphosphate of condensed diphenylamine-4-diazonium as described above. Particular preference is given to combining a diazonium salt unit with a light-insensitive condensable second component, such as aromatic amines, phenols, thiophenols, phenol ethers, aromatic thioethers, aromatic hydrocarbons, aromatic heterocyclic compounds and It is in the form of a water-soluble salt of a co-condensation product consisting of units of an organic acid amide. This type of condensation product is described in U.S. Pat.
No. 3849392, No. 3867147 and especially No. 4021243
It is stated in the specification of the No.

The layer of the invention may contain dyes such as rhodamine, triphenylmethane dyes such as crystal violet; astrazone orange, eosin, methylene blue, Victoria Rain Blue, etc. and/or water-soluble dyes which absorb in the radiation range and have a sensitizing effect. It is advantageous to add metal salts. Particularly preferred are the following metal salts: cobalt chloride CoCl ₂ ·6H ₂ O, uranyl nitrate UO ₂ (NO ₃ ) ₂ ·6H ₂ O, cadmium chloride CdCl ₂ ·2 1/2H ₂ O, ammonium iron sulfate ( ) _NH4Fe ( _SO4 ) ₂・
12H ₂ O, cadmium nitrate Cd (NO ₃ ) ₂・4H ₂ O, cerium chloride ()CeCl ₃・7H ₂ O, cadmium sulfate CdSO ₄・8/3H ₂ O, ammonium iron nitrate () (NH ₄ ) ₂ Fe ( SO ₄ ) ₂・
6H ₂ O, ammonium cerium nitrate () (NH ₄ ) ₂ Ce
(NO ₃ ) ₆ , cadmium acetate Ca (CH ₃ COO) ₂・2H ₂ O, cobalt acetylacetonate ()
C ₁₅ H ₂₁ O ₆ Co, Cobalt acetate () Co (CH ₃ COO) ₂・4H ₂ O, Sodium hexanitrocobaltate () Na ₃
[Co(NO ₂ ) ₆ ], nickel chloride NiCl ₂ 6H ₂ O, manganese chloride MnCl ₂ 4H ₂ O.

To produce the laser-sensitive printing plates according to the invention, the water-soluble salts of the diazonium condensation products and optionally one or more of the dyes and/or metal salts mentioned are dissolved in water and applied to the support and dried. . For good wetting, it is also possible to add small amounts of wetting agents, such as nonionic wetting agents and/or lower alcohols, such as methanol, ethanol or propanol. Coating can be carried out by centrifugal spraying, spraying, dipping or roller application.

The layer support of the recording material used in the method of the invention is produced by known methods. It is advantageous to roughen the aluminum mechanically, chemically or electrolytically before anodizing. The combination of electrolytic roughening and anodic oxidation has proven particularly advantageous in a continuous process. Roughening is carried out in a bath of dilute aqueous mineral acids, such as hydrochloric acid or nitric acid, using direct or alternating current.

The anodization is likewise carried out in an aqueous acid solution, for example sulfuric acid or phosphoric acid, preferably using direct current. In this case, the current density and anodization are adjusted to obtain an oxide layer thickness within a predetermined range. The layer weight should be at least 3 g/m ² . The upper limit of the layer weight is not critical, but generally above 15 g/m ² substantial improvements are no longer achieved. If the layer weight is too high, approximately above 30 g/m ² , there is an additional risk that cracks will form in the oxide layer during bending. A weight of about 5 to 12 g/m ² oxide layer is generally advantageous.

The UV-sensitive diazo layer according to the invention is developed after laser irradiation with an alkaline or acidic aqueous solution or with water itself. Also suitable are Lutzker emulsions or Lutzkers, as they are known as lithographic printing plates. Such lacquer emulsions and lacquers can be used in aqueous solutions in the process for development and lacquer application or after development.

For the purposes of the present invention, short wavelength lasers of reasonable power, such as argon and krypton lasers, are suitable, ranging from 0.5 to about 25 nm in the UV range, depending on the mirror used in each case.
It is emitted with an irradiation power of 1 watt or 1 to 25 watts within the visible range.

The laser beam is controlled by a predetermined programmed linear and/or raster movement. The method and apparatus for controlling the laser beam by a computer and the focusing, modulation and deflection of the beam are not an object of the present invention. These are, for example, West German Patent Application No. 2318133, pages 3 onwards.
No. 2344233, page 8 et seq. and U.S. Patent No.
It is described in the specifications of No. 3751587, No. 3745586, No. 3747117, No. 3475760, No. 3506779, and No. 3664737.

Example 1 A rolled photo-selected Al roll was continuously electrolytically roughened and anodized for 75 seconds at 40° C. with a direct current of 9 A/dm ² in an aqueous solution bath containing 150 g of H ₂ SO ₄ per liter. do. It is then treated with a 0.25% aqueous solution of polyvinylphosphonic acid at 70° C. for 30 seconds and then dried. Then 1 mole of 3-methoxy-diphenylamine-4-diazonium sulfate and 4,4-dimethoxymethyl-
Aqueous solution of 5.6% diazonium condensation product prepared by condensation of 1 mole of diphenyl ether and isolated as methanesulfonate and 0.56% cadmium chloride CdCl _2.2 1/2H ₂ O by roller coating method. Inspire.

The water-soluble salt of the diazonium condensation product is 85
% phosphoric acid from monomeric diazonium sulfate. It is present in the reaction mixture as a phosphate or hydrogen phosphate. From this mixture, the methanesulfonate salt can be precipitated by adding sodium methanesulfonate in concentrated solution in large excess (this methanesulfonate salt dissolves well in water). that time,
The precipitation is carried out according to the following reaction formula: R-N ₂ ⁽⁺⁾ H ₂ PO ₄ ^(-) +NaSO ₃ CH ₃ →R-N ₂ SO ₃ CH ₃ +NaH ₂ PO _4In the above formula, the group R is 3 -methoxy group-diphenylamine-group of condensation product of 4-diazonium salt and 4,4'-bis-methoxymethyl diphenyl ether: It is.

Irradiation is performed with an Ar laser having wavelengths of mainly 488 and 514 nm within the visible range at an irradiation output of 5 W and a recording speed of 40 m/sec. Wash and remove non-irradiated areas with water. The irradiated areas accept the offset printer oil-based ink and form a good printing plate.

Example 2 An Al plate pretreated with polyvinylphosphonic acid with an anodic oxide layer of 3 g/m ² was treated with diphenylamine-4-diazonium sulfate and formaldehyde in concentrated sulfuric acid with 85 parts by volume of water and 10 parts by volume of ethanol. 9.3 parts by weight of a diazonium condensation product and rhodamine 6GDN (CI45160) were condensed and the product initially present as a sulfate was then precipitated as a tetrachlorozincate based on the reaction formula below.
Apply 0.33 parts by weight of the solution by roller application.

The above diazonium condensation product, tetrachlorozincate, is water-soluble and has the reaction formula: 2R−N ₂ HSO ₄ +ZnCl ₂ +2HCl → (R−N ₂ ⁽⁺⁾ ) ₂ ZnCl ₄ ^(2-) +2H ₂ SO ₄ (in this case sulfuric acid is also formed from the added zinc chloride and hydrochloric acid). In the above formula, the group R
is the formula: It is.

Within the UV range, mainly wavelengths 363.8 and 351.1 nm
The sample was irradiated with an Ar laser having an irradiation power of 0.8 W and a recording speed of 50 m/sec, and then developed with water.

Add Rhodamine 6GDN dye to Astra Orange (C.
Equally good results are obtained when replacing it with I.48040) or crystal violet.

Example 3 An Al plate with an anodic oxide weight of 8 g/m ² was soaked in water.
It is coated with a solution containing 5.5% of the water-soluble salt of the diazonium condensation product described in Example 2 and 0.56% of cobalt chloride in a mixture of 90 parts by volume and 10 parts by volume of methanol.

Irradiate with an Ar laser in the visible range at a power of 5 watts and 100 m/sec and develop with a solution of 1% phosphoric acid and 0.5% gum arabic in water.

Equally good results are obtained if cobalt chloride is replaced by an equal amount of the following metal salts: cadmium nitrate, nickel chloride, manganese chloride, iron ammonium sulfate () or cadmium acetate.

Example 4 Anodized Al with oxide weight 3.5 g/m ²
The plate was placed in 80 parts by volume of water and 10 parts by volume of ethanol.
3-Methoxy-diphenylamine-4- in phosphoric acid
9.4 parts by weight of a salt of the crude condensation product obtained from diazonium chloride and formaldehyde (the condensation product is present as a hydrogen phosphate salt and is soluble in water), 0.56 parts by weight of uranyl nitrate and rhodamine.
Coat with a solution containing 0.33 parts by weight of 6GDN.

After irradiation with an Ar laser within the visible range at a power of 5 watts and a speed of 80 m/sec, the film is developed with a 1% phosphoric acid aqueous solution.

Example 5 Anodized Al with oxide weight 4 g/m ²
The plates are immersed in a 2% sodium silicate solution for 60 seconds at 80 DEG C., drained, dried and coated with a 6% aqueous solution of the water-soluble salt of the diazonium condensation product described in Example 2.

Irradiate with Ar/laser in the UV range at 2.5 watts and develop with water. To increase the printability, the image areas are coated with a Lutzker emulsion of the following composition: Non-aqueous phase: ethylene glycol methyl ether acetate
30 parts by weight cyclohexanone 40 parts by weight (Fatty acid condensation product with hydroxyethyl sulfonic acid) Relationship of addition of 2 parts by weight The invention of the original patent (Japanese Patent Publication No. 61-48418) uses a layer support having an oxide layer with a layer weight of at least 3 g/m ² A recording material having a layer support made of anodized aluminum and a recording layer on an oxide, the main part of which is to The object of this invention is a method for producing a lithographic printing plate which is made lipophilic and/or insoluble and then optionally washed away with a developer to remove the non-irradiated recording layer parts, the invention also includes a layer weight of at least 3 g/m. This is an invention of a method whose main part is the use of a layer support having an oxide layer of ^{No. 2} , and whose object is a lithographic printing plate, which is the object of the original patent application invention, and which is covered by Article 31, Section 1 of the Patent Law. This item falls under the item No.

Claims (1)

[Scope of Claims] 1. A recording material having a layer support made of anodized aluminum having an oxide layer weight of at least 3 g/m ² and a photosensitive recording layer on the oxide layer is imaged with a laser beam. A method for producing a lithographic printing plate in which the irradiated areas of the recording layer are made at least lipophilic or insoluble, and the irradiated recording areas are then washed away with a developer, in which a negative photocurable diazonium condensation 1. A method for producing a lithographic printing plate using a laser beam, characterized in that a recording layer containing a water-soluble salt of a product and an anion is used. 2. Process according to claim 1, characterized in that a layer support with an oxide layer having a layer weight of 5 to 12 g/m ² is used. 3. The production method according to claim 1, which uses a recording layer which additionally contains a dye or a metal salt as a sensitizer.