DE2251710A1 - PROCESS FOR MANUFACTURING CARRIERS FOR FLAT PRINTING FORMS AND THEIR USE - Google Patents

Description

PATENT ADVOCATE

DR.-ING. BY KREISLER DR.-INC. SCHÖNWALP DR.-ING. TH. MEYER DR. Ψ UES DIPL-CHEM. ALEK VON KREISLER DIPL-CHEM. CAROLA KELLER DR.-ING. KLOPSCH DIPL-ING. RARE

COLOGNE 1, DEICHMANNHAUS 2251710

Cologne, October 19, 1972 Ke / Ax / Ki / Bn

Howson-Algraphy Limited,

Vickers House, Millbank Tower, Millbank, London S.W.l

Process for the production of supports for planographic printing plates and their use

Planographic printing forms, their supports made of plates and sheets (including foils) made of aluminum or suitable There are aluminum alloys that have a surface provided with an anodic oxide layer known. To be suitable, the aluminum is cleaned to remove grease or other contaminants, and optionally mechanically, electrochemically or chemically grained in order to roughen the surface of the aluminum before the anodic oxidation. These carriers will be in contact used with both negative and positive working photosensitive layers of numerous types, either on the plates at the manufacturer's (presensilized plates) or, if required, from the lithographic printing plate manufacturer be applied.

The anodic layer can serve to increase the hardness, abrasion resistance, adhesion of paints or the surface Layers and give resistance to oxidation and corrosion and interact with the photosensitive Avoid layer or it can be used during printing because of its hydrophilic properties will. The use of anodic oxide layers for a wide variety of purposes outside of the graphic arts is also known.

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The process of anodic oxidation of aluminum can impair the properties of the anodic oxide layer. In the case of printing forms, it is common to use either the familiar one To use the sulfuric acid process or the phosphoric acid process.

Anodic oxide films formed using electrolytes containing sulfuric acid are hard and porous, and the thickness of these layers can be adjusted within narrow limits over a considerable range will. The porosity or the absorption capacity of these layers can be determined by various methods of "sealing" reduced or switched off. Sealing is generally the aftertreatment of an anodic Understand layer by which the absorption capacity of the layer for certain materials is reduced shall be. By sealing, for example, according to the method of British patent specification 78I 814 of the Applicant makes these layers more suitable for planographic printing, and the anodic layers are irrelevant whether they are sealed or not, much harder and more abrasion-resistant than the surface of the aluminum itself. Anodic oxide layers formed using an electrolyte containing phosphoric acid according to the method described in British Patent 1,244,723 in the name of the applicant Processes are formed also result in surfaces suitable for planographic printing.

The adhesive strength between a resinous, the printing ink Adopting lacquer layer and an anodic oxide layer is usually very good when the anodic oxide layer is in the unsealed condition. The seal can degrade this adhesive strength. For example, if a porous anodic oxide layer formed using an electrolyte containing sulfuric acid

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has been formed by impregnation with a colloid, for example according to the method of British patent specification 781 814 or according to the method of German

Patents (patent application P 22 05 706.3) of

Applicant is sealed, the adhesive strength of an organic resin lacquer accepting the printing ink, for example a "Tiefätzlaekes" (which can consist of a solution of a vinyl chloride-vinyl acetate copolymer in diisobutyl ketone) is greatly impaired, while the adhesive strength of an aqueous solution of a hydrophilic colloid is not is significantly impaired. Certain layers that are sensitive to skin, especially those that affect the product ^? Kodak Photo Resist "in that they consist of a solution of a high molecular weight resin substance, e.g. polyvinyl cinnamate, in an organic solvent, can be considered typical varnishes that are photosensitive and are best applied to suitable unsealed anodic oxide layers. In this case After processing, the printing form obtained usually has a printing surface with improved image areas.However, as set out in British Patent 781,814, the background or the non-printing areas of the printing form tend to accept the printing color, so that they cause disturbances during printing to lead.

Experience has shown that anodic layers are made using electrolytes based on sulfuric acid these difficulties with the non-imprinting areas without sealing are reduced if abnormally thin anodic layers are used. It's the natural hardship of having It is thanks to anodic layers formed by electrolytes based on sulfuric acid that this is possible.

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Planographic printing Forman, which are prepared from carriers which aluminum sheets -platter and sheets made of, which have been oxidized in the electrolyte based on phosphoric acid anodized, have recorded nichtdruekende areas. D. =, however, the anodic oxide layer is inevitably generally very thin, because a stage is soon reached in which the anodic layer dissolves as quickly as it is formed, they do not always have as high an abrasion resistance as desired.

The invention relates to unsealed anodically oxidized flat materials made of aluminum or aluminum alloys, which are suitable as a carrier for the production of flat printing forms that contain non-printing areas have improved abrasion resistance and reduced tendency to accept the ink.

The invention is used for the production of planographic printing forms Suitable carriers are available made from unsealed anodized plates, sheets and foils consist of aluminum or aluminum alloys and are manufactured by cutting the flat materials made of aluminum or aluminum alloys cleans and if necessary granulated, the cleaned and optionally granulated flat material washes, using a Electrolytes containing sulfuric acid are anodically oxidized and a porous anodic oxide layer is formed thereon, which For example, a basis weight of 1 to 6 g (or more) per m ", and the anodic oxide layer with a Treated phosphoric acid solution.

If the carrier material is granulated before the anodic oxidation, this can be done chemically, mechanically, for example using balls and abrasives or electrochemically using, for example

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of alternating current and an electrolyte containing hydrochloric acid "happen.

In the production of the carrier materials according to the invention, in addition to rinsing with clean water or very weak alkaline solution, no further treatment between cleaning and the optional one Granulation on the one hand and the anodic oxidation on the other hand.

During treatment with phosphoric acid, the grayish anodic oxide layer turns white. The concentration of phosphoric acid, together with the temperature of the phosphoric acid treatment bath and the duration of the treatment, play an important role in achieving optimal results. It has generally been found to be advantageous to use a 5 to 50% aqueous solution of orthophosphoric acid with a specific gravity of 1.75 at a temperature of about 20 ° C. for about 1 to 3 minutes, but the treatment can also be used at higher temperatures Temperatures can be carried out for a long period of time. A very strong lightening or whitening of the anodic oxide layer is achieved if the phosphoric acid is used in high concentration. In practice, an aqueous solution of phosphoric acid (specific gravity 1.75) with a concentration close to 30 % seems to be best. During the treatment with phosphoric acid, the anodic oxide layer is gradually removed, as shown in the figure, in which the final weight (in g / m) of the anodic oxide layer (which has been formed in the sulfuric acid electrolyte) depends on the duration of the treatment (in minutes) with 30% aqueous phosphoric acid at 19 ° C is shown graphically. The situation is similar when a direct current is applied to the phosphoric acid and the anodized plate to form an "anodic oxidation system".

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A number of variations are possible in the manufacture of cerium support materials according to the invention. For example, the electrolyte used in the anodic oxidation can contain other materials, for example phosphoric acid, in addition to sulfuric acid. The subsequent treatment with phosphoric acid can also be carried out using a bath which, in addition to phosphoric acid, contains one or more other materials, for example surface-active agents.

The carrier plates according to the invention can be in the most varied Way for the production of printing forms be used.

In one of these processes, the unsealed carrier plate (grained or non-grained as desired) is re-applied the phosphoric acid treatment sufficiently rinsed and dried, and then to form a photosensitive Plate for the production of planographic printing forms coated directly with light-sensitive material. Suitable as light-sensitive materials are, for example, positive-working materials based on quinone diaside, as described in Applicant's British Patent 1,245,963 to be discribed. Negative working materials, namely in organic solvents, are also suitable soluble, water-insoluble, photopolymerizable resin materials having multiple double bonds. For example, it has been found that a perfectly functioning planographic printing form of this type with an aluminum carrier a photosensitive plate is obtainable which has a polyvinyl cinnamate layer on a support according to the invention contains, which by cleaning and electrochemical graining of a plate made of aluminum or an aluminum alloy, Rinsing of the plate, anodic oxidation using the sulfuric acid process to form a hard, porous, non-

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sealed anodic oxide layer with a basis weight of about 6 g / m, treatment of the anodic oxide layer with a strong aqueous phosphoric acid solution, rinsing and drying of the treated plate is prepared before.

In this process, the is made from this carrier light-sensitive plate exposed imagewise in a known manner and then with a developer selected according to the photosensitive material of the plate, developed so that those areas of the imagewise exposed material which are more soluble in the developer are to be selectively removed. These more soluble areas may vary depending on the type of light-sensitive material and the developer used Light struck areas or the unexposed areas. The printing form obtained has printing areas, the less soluble areas of the imagewise exposed area that remain on the support after development Material are formed, and non-printing areas are created by the underlying areas of the Supports that are exposed when the more soluble areas of the imagewise exposed material are developed removed, formed.

In a second method, the (granular or ungrained) unsealed plate after the phosphoric acid treatment, rinsed and dried and used as a printing plate carrier is used, which does not need to be sealed before it can be used in certain reversal processes of producing printing images suitable is. If these carriers are to be used for the production of planographic printing plates, they will coated with a photosensitive material suitable for the printing form manufacturing process to be used, whereby a photosensitive plate is obtained. For example, they can be made with dichromated polyvinyl

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Alcohol coated as it is known for dar Polyvinyl alcohol process of printing form production are particularly well suited. This process consists essentially in the fact that the dichromated Polyvinyl alcohol existing layer of photosensitive Plate exposed imagewise, the exposed layer developed selectively, the areas not struck by the light the layer is removed and the areas of the carrier material below these areas are exposed, if necessary, etches the exposed areas, a material that accepts the printing ink, e.g. a lacquer applies the developed plate and the areas of the layer struck by the light and the one above the light struck areas Areas of the layer. The ink-accepting material is removed. The printing form obtained has printing areas, which are due to the ink-accepting material on the areas of the carrier plate, which are under the unexposed areas of the layer are formed, and non-printing areas that are formed by the areas of the carrier plate, which upon removal of the exposed areas of the layer were exposed. In this way it is possible to j Printing forms with long printability for high im- j were based on a very simple photomechanical method; drive manufacture.

In a third method, the unsealed carrier plate is sufficiently rinsed after the phosphoric acid treatment and then sealed in a suitable manner, for example after ^! the process of the German patent specification (patent application P 22 05 7G6.3) or the process of the British patent specification 78I 814 of the applicant, whereby an all-purpose planographic printing form carrier is obtained which is suitable for the various on reversal processes of printing form production, in which usually from Posi -

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tiveri is assumed. The sealed plate can then for example with a lichtenpfinälicnen Material, e.g. a photosensitive * colloid, e.g. Gum arabic, coated v / ground, being a photosensitive Plate is obtained, which is then used for manufacture a printing form can be exposed and processed in the usual way. For example, the light « sensitive plate after the deep etching process to a Printing form are processed. In this procedure essentially worked as follows: One beliclvtet the Layer image-wise, unraveled the image-wise exposed one Layer selectively so that the unexposed lit areas of the layer are removed and the areas below these areas Places of the carrier material are exposed, this etches Areas of the vehicle, transfer a print color accepting Material, e.g. a lacquer, on the etched plate on tir.d removes the exposed areas of the layer. and that over the ink-accepting material lying in the exposed areas of the layer. The printing form obtained has printing areas created by the ink-accepting material on the etched areas of the substrate are formed, and non-printing areas which are formed by those areas of the carrier material which have been exposed during the removal of the exposed areas of the layer.

It should be noted that in addition to the washing and drying treatments, if any, and any one possible Sealing treatment the panels after phosphoric acid treatment and before coating with the light-sensitive material should not be subjected to any other treatment. Whether a sealing treatment is done will or not depends on the kind of photosensitive material to be applied and the kind the process to be used for printing form production.

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The invention is further illustrated by the following examples, examples 1, 2, 5 and 6 are comparative examples.

Example 1

A plate made of commercially available pure aluminum became known in. "'- ice degreased and electrolytically using el:' ■ electrolytes consisting of dilute hydrochloric acid. ·., Which gives the plate a roughened surface. a very thin, corrosion-resistant oxide layer. This granular flatten had an oxide layer weight of 0.75 s / w. The flat was rinsed in tap water and then coated with a photosensitive material based on polyvinylcinnane (trade name "Kodak Photo Resist") in such an amount that the dry layer had a basis weight of 0.5C g / m ¹ ". The photosensitive plate obtained was then exposed in the usual way under a negative and processed, a printing form being obtained which was mounted on a planographic printing machine.

The printing form worked well and resulted in an edition of 50,000 good copies, but the printing form showed under the experimental conditions at this point there was slight evidence of an adverse change in the printing and non-printing areas as a result of abrasion and ink acceptance by the non-printing areas.

Example 2

A plate made of commercially available pure aluminum was degreased in the manner described in Example 1 and electrolytically roughened. Immediately after roughening and rinsing, the plate was placed in a sulfuric acid bath (specific gravity 1.2 ^) and then so anodic oxidized so that an anodic oxide layer with a weight per unit area of 2.00 g / m 2 was formed. The anodically oxidized Plate was rinsed and dried. The anodic

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The oxide layer was greyish in color. After loading: Layering and processing have encountered difficulties during printing as a result of the ingestion of ink through the non-printing areas of the printing form.

Example 3

A plate made of commercially pure ■ aluminum was used degreased in the manner described in Example 2, electrolytically roughened and then anodically oxidized, but with a thicker anodic layer to compensate for the loss was applied in the phosphoric acid bath. After the anodic oxidation, the plate was washed with tap water rinsed and then 2 minutes at room temperature in. its 3C # solution of orthophosphoric acid (specific gravity 1,750) and then carefully washed again in water and dried. The anodic oxide layer was White. The plate was then coated with the photosensitive polyvinyl cinnamate in the manner described in Example 1 "Kodak Photo Resist", coated and then exposed, processed and printed on the ■ game 1. used. In this case, the printing forme produced a print run of 50,000 good copies achieved on the same printing machine using the same paper as in Example 1 »Die The printing form showed a significantly lower disadvantage Change in the printing and non-printing areas due to abrasion. In contrast to Example 1 resulted there are no problems with accepting ink in the non-printing areas.

The printing form was obviously better than the one according to Example 1 produced printing form and resulted in a total print run of 70,000 good copies before the Showed effects of abrasion.

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example

The experiment described in Example 3 was repeated with the difference that the conditions for the roughening and for the anodic oxidation were chosen so that the weight of the final oxide film ^ »5 ε / ™ *" was increased. In this case, the printing form showed very good typographical behavior and negligible Signs of wear and tear from abrasion upon completion of printing an edition of IOC 000 copies among those mentioned in Example 3. Conditions. During the printing of this edition, the non-printing areas of the printing form took no printing ink at.

Example 5

The experiment described in Example 3 was repeated with the difference that the roughened plate was brightened by immersing it in a standard cleaning solution for 2 minutes after the anodic oxidation was, the 5 Vol.-Ja nitric acid and 5 Vol.-J ^ - Contained hydrofluoric acid (instead of phosphoric acid). During development it was shown that * that The printing image adhered very poorly to the carrier.

Example 6

The experiment described in Example 3 was repeated with the difference that after the anodic oxidation and rinsing, the carrier is diluted with a hot one Gum arabic solution to that in the British patent 781 814 described manner was sealed and not treated with the phosphoric acid solution. In the At the development stage of processing, it was found that the printed image adhered poorly to the support.

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Example 7

The experiment described in Example 3 was repeated with the difference that the carrier was not coated with the Kcdak Photo Resist, but with a positive-working coating solution containing 10 g of 2> 4-dihydroxybenzophenone bis ^ ~ naphthoehinone (1,2) -diazic. ~ (2) ~ 5-sulfonate7 in 100 ml of 2-ethoxyethanol, 200 ml of the above solution of a cresol novolak parses (Alnovol ^i: -29X) in 2-Äthojcyäthaiiol and 0.35 pounds of polyvinyl hydrogen phthalate. The photosensitive plate obtained was exposed under a positive with a fine grid. After development with a dilute alkali and subsequent desensitization of the non-printing areas, a print run of 90,000 excellent, clean copies was achieved with the printing form obtained on a small offset printing machine.

Example 8

The experiment described in Example 7 was repeated with the difference that the aluminum before the anodic Oxidation was only degreased instead of degreased and grained. The positive working photosensitive obtained Plate was exposed under a line positive and with an alkaline "positive plate developer" (manufactured by the applicant) processed. The developed plate was then desensitized, gummed and dried.

The printing form was on the cylinder of a small offset printing machine stretched and produced very clean prints of good sharpness without difficulty.

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Example 9

A plate made of commercially available aluminum was' on the In the manner described in Example J5, degreased, electrolytically grained and anodically oxidized.

The anodized plate was rinsed in tap water and then 2 minutes at room temperature with a 20% aqueous phosphoric acid solution (specific weight 1.75) in order to whiten the anodically oxidized surface and its desired properties for the production of printing formes and to give good printing properties. The slack was treated then rinsed and dried well and in a dry place Atmosphere kept between clean paper containers.

The plate was later taken from the warehouse, wetted with water and dlchromatized with a thin layer of Polyvinyl alcohol solvent ("Poroplast", Manufacturer Howson-Algraphy, N.V., Holland). After drying, the photosensitive plate obtained was under a line positive for 2 minutes with a exposed to an open carbon arc. It was then removed and washed under clean running water with a cotton ball cleaned. After careful development and thorough washing, the plate was demineralized with rinsed and desalinated water and dried. A thin layer of an imaging vinyl varnish was applied applied and dried, whereupon the plate colored with a thin layer of a greasy printing ink became.

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After brief immersion in water, the Polyvinyl alcohol stencil removed and oil plate desensitized with gum arabic, with a usable one Printing form was obtained. An attempt to print it was found that a large print run of clean and good copies can be obtained.

Example 10_

A plate made of commercially pure aluminum was degreased, grained and anodically oxidized in the manner described in Example 4. The anodically oxidized plate was rinsed and then treated with a weak (5%) phosphoric acid solution (specific gravity 1.75) for 3 minutes at room temperature. After rinsing, the treated plate was sealed and desensitized by an aqueous solution of gum arabic and polyvinyl alcohol was applied., as described in the German patent ......... (patent application P 22 05- 706.3) of the applicant in. To produce a printing form from the sealed plate, it was washed with water and coated in the usual way in a centrifuge with a deep-etching solution of chromated gum arabic. According to the "Howter" deep etching process (developed by the applicant) in accordance with. According to the published instructions, a good planographic printing form was obtained which was still printable after printing an edition of 210,000 good copies. In contrast, the same plate, which, however, had not been subjected to the phosphoric acid treatment, was not received favorably by the customers, for whom a dark background is synonymous with a tendency to accept printing ink.

Example 11

A degreased aluminum foil was grained, washed and then immersed in a bath of a 15% sulfuric acid solution.

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sung 15 minutes at a temperature of 22 C and one Current density of 1 A / dm "anodically oxidized. Oils foil was then taken out of the bath ·, spttlt and in one Bath containing 30 # aqueous phosphoric acid solution, Treated at 22 C for 3 minutes. A direct current of 1 A / dra was during this treatment by the bath and; the Slide passed. The slide was then placed in tap water rinsed and dried well.

A layer of the positive working photosensitive material described in Example 7 was applied to the sheet was applied to form a photosensitive plate. The plate was positively exposed under a notch and processed in the manner described in Example 7. The developed plate was then desensitized. The printing form obtained was flawless and proved itself in the same way as the printing form produced according to Example 7.

Example 12

A thin aluminum foil was degreased, grained and rinsed. It was then anodically oxidized in an electrolyte consisting of a mixture of 15% sulfuric acid and 5% phosphoric acid for 8 minutes at a bath temperature of 20 ^° C. and a current density of 2.5 A / dm. After this mixed anodic oxidation, the B ¹ oil was rinsed and immersed in a bath consisting of 22% phosphoric acid at room temperature for 2.5 minutes. The film was then rinsed and desensitized by treatment with hot gum arabic solution. A print image was then formed on the sealed film using the deep-etching process carried out in the manner described in Example 10 using the dichromated gum arabic. With this printing form, an edition of 200,000 good copies with a sharp print image was obtained.

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, - 17 -

Example 13

Aluminum plates were degreased, grained, rinsed and anodized in the manner described in Example 4. The anodized plates were then rinsed and lightened or whitened in 20% phosphoric acid solution at room temperature for 2 minutes. The plates treated in this way were then rinsed and dried, whereby blanks of planographic printing plates were obtained. A total of 100 beams, each 114.3 x 72.4 cm in size, were produced. All these unsealed carrier were processed in a print shop according to the procedure described in Example 9 _r photo-mechanical process using polyvinyl alcohol to von'dichromatisiertem Plachdruckformen which subsequently used as desired in the printing ■ were. With these printing forms, print runs of over 100,000 clean copies were obtained without difficulty.

Example 14

A flat aluminum plate with a thickness of 0.66 mm was cleaned in a known manner and with balls, which with an aqueous slurry of an abrasive, back and forth on a grit machine Moving tub mechanically grained. The spheres were made from steatite, which is a form of hydrated magnesium silicate. The commercially available material containing alumina was used as the abrasive in the slurry "Aloxite" used. The fine-grained surface was rinsed to remove the sludge, whereupon the Plate in a bath containing 30 $ sulfuric acid (specific gravity 1.250) and about 20 g of aluminum sulfate per Liter, anodically oxidized for 6 minutes at a current density vprr 4 A / dm. After taking out the anodic oxidized plate from the bath, it was rinsed and 3 minutes at room temperature with 28% aqueous Phosphoric acid aftertreated. The treated plate was

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then rinsed and using hot gum arabic solution sealed.

The sealed plate was then used in the manner described in Example IO, the same good results have been obtained.

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Claims (1)

225171Ö Fate η ta ϊϊ s ρ τ ü e he 1.) Process for the production of supports for flat printing molds., characterized in that one has a flat carrier the end. First clean aluminum or aluminum controls, then containing the purified carrier in a sulfuric acid Electrolytes forming a porous oxide ^ layer anodically oxidized and the oxide layer finally treated with an aqueous phosphoric acid solution. 2.) The method according to claim 1, characterized in that daS one an aqueous containing 5 to 50 vol. $ phosphoric acid Solution with a specific gravity of 1.75 used. 5.) Method according to claim 1 or 2, characterized in that that the carrier is grained, preferably electrochemically, prior to cleaning and anodic coding. 4.) The method according to claim Ibis>, characterized in that that one sees an oxide layer with a surface weight of 1 to 6 g / m 2 produced. 5.) Method according to claim 1 to 4, characterized in that that after the treatment with the aqueous phosphoric acid solution, the support is washed and dried. 6.) The method according to claim 1 to 4, characterized in that the anodic oxide layer after the treatment sealed with the phosphoric acid solution. 7.) Process according to claim 1 to 4, characterized in that the carrier is washed after the treatment with the aqueous phosphoric acid solution and the treated anodic oxide layer is coated with a photosensitive material. . ' _: 309822/1148 BAD OR5G1NAL 8.) Process according to claim J _1, characterized in that a photosensitive material containing a quinonediazide is used. 9.) The method according to claim 7 j characterized in that da.3 one uses a photosensitive material which is soluble in an organic solvent, in water contains insoluble photopolymerizable resin having a variety of unsaturated bonds, preferably polyvinyl a namat. 10.) Use of a carrier according to one of the preceding claims for the production of planographic printing plates, wherein the anodic oxide layer of the support with a photosensitive material based on dichromated Coated with polyvinyl alcohol or a colloid, and this coating is imagewise exposed and selectively for removal the more soluble areas of the coating is developed. BATH ORIGINAL
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