MXPA99010645A - Laser imageable printing plate and substrate therefor - Google Patents

Abstract

A metal substrate is treated with a plurality of rotating brushes and a slurry of particulate material such that the treated surface is capable of absorbing incident infrared laser radiation. The substrate is itself capable of being visibly imaged by selective writing with an infrared laser. The substrate is coated with an ablatable coating which is transparent to the imaging infrared laser radiation. Selective exposure to infrared laser radiation ablates this coating in the laser exposed areas as a result of the absorption of infrared radiation by the substrate. The substrate can be anodized after rotary brush graining and still retain its ability to be imaged and ablate a coating. The coated article can be imaged in a computer-to-plate infrared laser imaging device. Depending on the specific coating and substrate selection, the imaged article can be used in a conventional lithographic printing process or in a dryographic printing process.

Description

PRINTING PLATE FOR FORMING IMAGES BY LASER AND SUBSTRATE FOR THE SAME DESCRIPTION OF THE INVENTION This is a continuation request in part with Serial No. 09 / 019,829 filed on February 6, 1998, which is a continuation in part of the copending provisional application Serial No. 60 / 047,447 filed on May 22, 1997, all of which are hereby incorporated by reference. The invention relates to a metal substrate in which images can be formed, in particular with a coated flattening substrate in which laser images can be formed to form a printing plate. Conventional lithographic printing plates, such as those that are typically used by both commercial and newspaper printers, are usually made of a granulated anodized aluminum substrate which has been coated with a light sensitive coating. The granulated anodized aluminum is generally subsequently treated to improve the hydrophilicity of the substrate sheet prior to the application of the light sensitive coating. Solutions that are useful for the post-treatment include, for example, sodium silicate and polyvinyl phosphonic acid.

Aluminum granulation is achieved in a variety of ways, including rotating brush granulation, chemical granulation and electrochemical granulation. It is possible to use more than one of the same techniques in the production of lithographic substrates. A granular surface has better addition to the light sensitive coatings and transports the wetting solution in the background areas of the plate in the press more efficiently than the non-granulated surface. Anodization is the process of electrolytically generating aluminum oxide on the surface of the aluminum sheet. Anodizing electrolytes commonly used include sulfuric acid and phosphoric acid. Since anodic aluminum oxide is harder and more resistant to abrasion than aluminum, an anodized printing plate has a longer press life than a smooth plate. Computer-to-board systems that use infrared lasers are now available to image on printing plates. By forming the images directly on the plate, the use of photographic negatives is eliminated. U.S. Patent No. 4,731,317 to Fromson et. al., discloses a printing plate based on a substrate which is granulated by brushing in a suspension comprising alumina, followed by successive treatments in dilute nitric acid and sodium hydroxide, and the subsequent anodization to achieve an oxide coating with weight of 1.5 milligrams per square inch. The substrate can also be silicate coated after anodizing to improve hydrophilicity according to U.S. 3,181,461. The anodized plate is then coated with a diazo resin which is transparent to the YAG infrared laser radiation (1064 nanometers), but sensitive to the longer wavelengths generated within the areas of the anodic oxide exposed to the laser. The theory is that the grainy surface traps laser radiation and re-emits energy as longer wavelengths. The property to catch the light must be improved by the addition of carbon black to the diazo. The diazo is insoluble where the plate is exposed to the laser. After exposure of the laser, the unexposed diazo is removed with a solvent to reveal the hydrophilic oxide in the background. Because areas without imaging are removed with a solvent, the plate is described as negative work. U.S. Patent No. 4,731,317 mentions that the diazo may partially wear out when the level of the laser radiation is relatively high. Such wear is undesirable since the areas exposed to the laser radiation must remain on the plate as an ink-carrying image after processing in the developing solution.

In accordance with the present invention, a curved or flat metal substrate is treated in such a manner that the surface is capable of forming visible images by selective writing with an infrared laser. A preferred treatment for this purpose is granulation by a rotating brush. The phrase "granulation by a rotating brush" is intended to refer to any process that utilizes axial rotating brushes that tangentially contact a surface to be granulated in the presence of a suspension containing particulate material such as alumina, silica and the like. The phrase also includes equivalent processes that produce the same result. The treated surface is coated with a wear-resistant coating which is transparent to infrared laser image-forming radiation. Selective exposure to infrared laser radiation wears this coating on the areas exposed by the laser as a result of the absorption of infrared radiation by the treated metal surface. Images may be imaged on the coated substrate in a computer-to-plate infrared laser imaging device, depending on the specific coating and the substrate section, the substrate with formed images may be used in a conventional lithographic printing process or in a driographic printing process.

The printing plate of the invention thus comprises a metal substrate with a laser-wear coating thereon wherein images on the substrate itself can be imaged with lasers. The preferred metal substrate is aluminum which is preferably anodized after being treated to provide the substrate in which images can be formed by an infrared laser. The anodized aluminum can optionally be further treated with sodium silicate, polyvinyl phosphonic acid or the like to improve the hydrophilic nature of the non-image forming areas. The wear-resistant coating itself does not absorb the wearing infrared laser radiation, as it is transparent to it. The infrared laser radiation for imaging passes through the coating? _ Is absorbed by the treated metal substrate. The coating on the laser-imaged areas wears out as a result of the incident infrared energy captured by the treated metal substrate. This coating in areas not exposed to laser radiation imaging remains attached to the plate. The substrate of the invention has three functions. First carries a wear-resistant coating. Second, it is capable of absorbing infrared laser radiation to abrade the coating. Finally, it is transformed into the printing plate where the areas worn by the functional laser as the image or the second plane depending on the choice of the coating and the printing mode, ie lithographic or driographic. Because the substrate itself causes the laser wear of the coating, which functions as the image or the background after imaging and by laser, no intermediate layer or coating is required to promote or cause it to be carried out. the wear. In another embodiment, the wear-resistant coating acts positively with respect to the formation of images by ultraviolet radiation. Worn (or imaging) plate by infrared laser is exposed in a blanket to ultraviolet light to a point sufficient to solubilize the wear particles that remain in the background area without substantially affecting the image on the plate. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross section of a metal substrate useful in the invention; Figure 2 is a cross section of a printing plate according to the invention; Figure 3 is a cross section showing the laser wear of the top coating; Figure 4 is a cross section of a printing plate with a sub-coating; Figure 5 is a cross-section showing the laser wear of the upper coating of the plate of Figure 4. Figures 6 A-C are SEMS of surfaces 1P, 2P and 3P at 100,000X of amplification. It has been found that sufficient treatment of a metal substrate by granulation by a rotating brush produces a surface on which visible images can be formed by selective exposure to infrared laser radiation. Additionally it has been discovered that when the treated substrate is coated with a wear-resistant coating and selectively exposed to the infrared laser radiation, the coating wears selectively in the areas exposed to the laser. The amount of rotary brush granulation required to impart infrared laser image forming capability can be determined empirically. For example, three samples were prepared representing different degrees of granulation by rotating brush. The same brush granulation unit and the same brushes were used for each sample. The frame in the granulation brushes contained 8 brushes, each 35.56 cm (14 inches) in diameter. The brush filaments were 5.08 cm (2 inches) long nylon. The brushes were rotated axially at 750 rpm. The suspension contained 33% unmelted laminated alumina. An aluminum network was passed through the granulator unit by brush at a speed of 80 feet per minute. A sample was removed and identified as 1P (one pass). The already grained web was passed through a brush granulation unit at the same speed of 80 feet per minute a second time. A sample was removed and identified as 2P (two passes). The granulated aluminum network was twice again passed through a brush granulation unit at the same speed for the third time. A final sample was removed and identified as 3p (three passes). Figures 6A-C are SEMs of surfaces 1P, 2P and 3P at an amplification of 100,000X. All plate samples were subjected to infrared laser imaging in a Gerber Crescent 42T Plate Image Setter manufactured by Gerber Scientific of South Windsor, Connecticut. The conditions of imaging were the same for each sample. The sample 1P had an image which was very little visible. The 2P sample had a more visible image, but the contrast was still weak. The 3P sample had a strong lived image. Although the three samples were found to have similar topography as characterized by conventional styling profiling and hardness measurement techniques, the ability to image by laser is significantly different for the samples. While not limited by any particular theory, it appears that the extensive particle embedding during the granulation process provides the unique character of the surface on which images can be formed. Rotary brush granulation results in a surface where multiple particles (eg calcined alumina) are embedded within the surface of the sheet, most of which is covered by a metal skin as a result of extensive erosion. The particles have a low thermal conductivity in relation to the metal. Thus, hard particles (relative to the metal substrate) with low thermal conductivity, especially hard metal oxide particles, are preferred for use in the present invention. These particles embedded within the metal matrix produce a sinuous path and thus less efficient for heat dissipation. The energy captured on the surface can not be efficiently transferred to the substrate by means of the thin cross sections through which the thermal continuity to the volume of the substrate metal sheet is maintained. This results in a temperature increase on the surface of the granulated metal sheet which is efficient to cause a certain amount of localized melting of the aluminum on the surface. While it has been shown that rotary brush granulation is an efficient method to produce these surfaces, other equivalent methods such as high pressure lamination, blasting blasting, pelletising, or the like, which produce a metal surface with a relatively high degree of embedded particulate material may also be used. Not all granulation methods are suitable to produce a surface on which images can be formed with an infrared laser. For example, granulation techniques that do not embed particles such as chemical or electrochemical granulation, known to produce suitable lithographic surfaces, do not produce a surface on which images can be formed by an infrared laser. However, these techniques can be used for special purposes taking into account that the substrate is subsequently granulated by a rotating brush. Rotary brush granulation typically increases the roughness of the surface. However, the present invention does not require that the roughness of the substrate be increased to be able to image by laser in it. For example, it is possible to electrochemically stamp or granulate a substrate to produce a thickly eroded surface, in which laser images can not be formed by itself. Rotary brush granulation as described herein will provide a substrate in which images can be imaged by laser and will also reduce the roughness of the surface as can be measured, for example, by a stylet-like profiling instrument. Likewise, the jet with very fine particles can reduce the roughness of the surface of a substrate having a rougher initial topography. The present invention requires the treatment which provides a substrate in which images can be imaged with an infrared laser, but which the roughness of the surface can be increased or decreased as a result of rotary brush granulation or an equivalent treatment as described at the moment. Subsequent to the brush granulation process, treatment with harsh chemicals can cause the surface to lose its ability to form images by laser. For example, etching with sodium hydroxide, as described in US Pat. No. 4,731,317, alters the surface in such a way that images can not be formed therein. Additionally, excessive anodization in electrolytes such as sulfuric acid or phosphoric acid can alter the surface in such a way that images can no longer be formed. It is believed that these types of treatment remove embedded particles and thus alter the efficiency with which thermal energy is conducted from the surface into the substrate sheet. It is possible to anodize the granulated surface by brush and retain the ability to image on the surface with infrared lasers. Anodization in sulfuric acid at low temperatures with relatively low oxide coating weights is effective to produce a surface on which laser images can be formed and still have the hardness and durability necessary for printing. An anodic oxide thickness of about one or less, preferably about 0.5 micron, is most suitable. Although aluminum is the preferred substrate, other metals can be granulated by rotating brush according to the present invention, coated with a wear-resistant coating, and selectively imaged with an infrared laser in such a manner that the coating wears out in the areas written with To be. Suitable metals include zinc, tin, iron, steel and alloys thereof. Metal laminates can also be used as tin, zinc, lead and alloys thereof. Pvßvestidos or plated on steel. A steel surface granulated by a rotating brush will absorb infrared laser radiation to selectively abrade a coating as described herein but in which the images themselves can not be formed as is the case with aluminum and other metals. In a preferred embodiment, the substrate is prepared in a continuous roll anodizing line. The aluminum netting is first subjected to a cleaning or degreasing process to remove the residue of rolling oil from the surface. These processes are well known in the art of preparing the aluminum surface for subsequent anodization. The aluminum net is rinsed in water after the cleaning step. It is then subjected to a rotary brush granulation process using a series of axially rotating brushes which tangentially contact the network in the presence of a suspension comprising unmelted laminated alumina having particle sizes of 2 to 5 microns to about 10 microns. mieras As previously described, three passes are made through an eight-brush granulating unit at 80 feet per minute resulting in a surface on which laser images can be formed or which can cause a wear-resistant coating to wear away from the surface. surface. An equivalent result can be obtained either through a single pass through the eight-brush granulator or at a total throughput speed of approximately 27 feet per minute, or through a single pass through a 24-brush granulator at 80 feet per minute. . Although subsequent anodization is preferred, the granulated aluminum surface itself can also form images and a coating on it can be caused to wear out when images are formed by an infrared laser. A useful method for granulating is taught in the North American Patent 4,183,788 of Fromson. After the granulation, the aluminum network is rinsed in water and anodized by means well known in the art. Referring to Figure 1, the aluminum net 10 has an eroded surface 12 and an anolytic oxide layer 14. The electrolyte may be, for example, sulfuric acid or phosphoric acid. Sulfuric acid is preferred since it allows the formation of oxide at lower dissolution levels. The preferred anodization is additionally carried out at relatively lower temperatures to further minimize the redissolution of the anodic oxide coating with the additional benefit of producing a harder oxide layer than the anodization processes at higher electrolyte temperatures. Preferred oxide coating weights are in the range of 0.1 to 3.0 milligrams per square inch, more preferably approximately 0.2 to 0.8 milligrams per square inch. U.S. Patent No. 29,754 of Fromson describes a preferred method for anodization. It has been found that coatings comprising certain phenolic polymers or silicone resins can be abraded according to the present invention. The wear of the coating seems to occur without any evidence of burning, charring or any other change other than that which is converted to a residue or fine powder. However, the invention is not limited to these two kinds of coatings. Other wear coatings can be determined empirically. The wear coating may not be sensitive to light, such as phenylmethylsiloxanes or light sensitive, such as S? Positive active coatings based on phenolic resins. Such positively acting coatings are well known in the art and have been found to wear easily with an infrared laser when applied to a substrate of the present invention. The laser removes the areas in the background leaving the phenolic resin or finylmethylsiloxane in the areas where no laser images were formed on the plate. Positive-acting coatings can also be used with a second top coat which is transparent to infrared laser radiation but which may or may not itself be wear-resistant from the substrate of the invention. In this way, if you want to present a special surface for a particular application, which can only be provided by a non-abradable coating, a wear-resisting sub-coating on the substrate with a top coating of the non-abradable coating will allow selective laser wear of both layers. For example, in waterless or driographic printing, the second plane should have a low surface energy to repel the printing fluid which is transported through the image areas of the plates. Crossed polysiloxane polymers such as those described in Example 12 and 13 herein, have a surface energy sufficiently low to be used as non-imagers or in the background of a driographic plate but can not be abraded from the substrate of the invention. The top coating of a cross-polysiloxane coating on a positive working coating on the substrate allows the laser wear of both coatings simultaneously from the image areas on the substrate. In this way, a positive working coating is used to form a negative work plate and is the means by which an otherwise non-wearing coating can be selectively removed from the substrate of the invention. Phenolic resins are known as useful as the image area formers in a printing plate, and in addition they can be adjusted to heat to provide a durable image capable of making very long printing runs. Examples of phenolic resins useful in the practice of this invention, such as Novolac or resole resins, are described in Chapter 1CV of "Synthetic Resins in Coatings," H.P. Preuss, Noyes Development Corporation (1965), Pearl River, New York. The wear coat should be as thin as possible but still adequately cover the substrate to provide a durable image for printing. Coating weights in the range of approximately 50 to approximately 500 milligrams per square foot can be used, but it is preferable to work in the range of approximately 100 to 200 milligrams per square foot. Coatings, thicker ones require more time and energy to wear out. This is an important factor in the newspaper publishing industry, where large numbers of plates must be prepared in short periods of time. Reducing the coating weight from 200 milligrams per square foot to 150 milligrams per square foot can result in a reduction in the laser exposure time of approximately 15. A second top coating, when used, is preferably approximately the same thickness as the wear coating.

When a positive working light-sensitive phenolic resin coating is used, it is preferred, after the wear, to expose the plate with laser imaging arrays with sufficient ultraviolet light to solubilize any residue of the coating which remains in the coating. background. This relieves any undesirable ink collection in the areas where no plate images were formed in the press. A short exposure of approximately 25 milijoules per square centimeter will solubilize any resin in the second plane, which is then removed, for example, with an alkaline cleaning solution. This blanket exposure accounts for approximately 8 to 10% of the total energy normally used to expose a positive resin. A thin film of the resin coating will also be removed from the image area, but those losses are in the order of 4% and are tolerable. The coating still retains its integrity in the printing process. Laser imaging systems use YAG infrared lasers that operate at up to 15 watts. Gerber Scientific of South Windsor, Connecticut and Sean Graphics of Wedel, Germany provide commercial computer-to-plate systems which can be used to image plates prepared in accordance with the present invention.

The following examples are illustrative and not limiting. Example 1A Several samples and two comparative samples were prepared from an Alcoa 3103-H26 aluminum alloy roll. The roll was granulated by rotating brushes and anodized by varying the conditions set forth in the following table. All samples except T-30 are anodized in 25% sulfuric acid. T-30 was anodized in a 2% tartaric acid solution.

All the samples were placed in a Gerber Crescent 42T Píate Image Setter and exposed in the sense of the image with the YAG laser at 9, 7 and 5 wats. After the exhibition, a permanent visible image was created in samples EX 140, 147, 148 and T-30 at all energy levels. Samples EX-113 and Delta are comparative examples which have been etched into a sodium hydroxide solution and flashed in a nitric acid solution before anodization. Engraving destroys the ability to form images in these samples. Example 1 A 12.5% solution of Dow Corning Silicone Resin 6-2230 in PM acetate was applied to three separate samples of the Ex-140 anodized substrate of Table 1 at three different coating weights; 100 mg / square foot, 150 mg / square foot, and 200 milligrams per square foot respectively. The coatings were dried in an oven at 90 ° C for two minutes, to produce a layer of silicone 14 as depicted in Figure 2. The weight of the anode coating was 2.8 milligrams per square inch. The simple coated aluminum plate thus prepared was then mounted on a Gerber Crescent 42T Plate Image Setter which has an internal drum configuration. It was equipped with a 10-watt, 1074 nm laser? AG manufactured by Light Wave Inc. Images were formed on the 150 Hz coated plastic samples, with a spot size of 10 microns, and a dwell time of 36 nanoseconds. , at energy levels of 10, 9 and 7 wats. Figure 3 represents the wear process, the silicone 16 is selectively weathered to expose the oxide layer 14. The silicone coating of 200 mg / square foot wears cleanly at 100 watts, was partially worn to 9 watts and did not wear out at 7 wats. The silicone coating of 150 mg / square foot was cleanly weathered at 10 and 9 wats, and only partially weathered at 7 watts. The silicone coating of 100 mg / square foot was cleanly woven at 10, 9 and 7 wats. It is obvious from the results that thicker coatings (higher coating weights) require more laser energy to wear cleanly, and conversely, thinner coatings require less laser energy to wear cleanly. Example 2 A series of Dow Corning resins based on polymethylphenyl siloxane were prepared as in Example 1. The resins were designated Dow Corning Resins 1-0543, 6018, 840, 804, and 806A. These resins vary in the percentage of phenyl substitution and molecular weight; they are all film formers at room temperature. These resins were applied to an anodized substrate EX-140 of Table 1. The weight of the coating was 150 mg / square foot for all samples. Images were formed in the samples of silicon-coated plates thus prepared at 9 wats in the Gerber Crescent 42T Píate Image Setter. All samples weathered cleanly. Example 3 A brush-granulated, amodized aluminum substrate was prepared similar to Example 1, except that the weight of the nano film coating was 0.5 mg / square inch (sample EX-147, Table 1). The aluminum sample was then coated with Dow Corning Resin 6-2230 or 150 mg / square inch. The aluminum plate with a single coating was placed on the Gerber Crescent 42T Plate Image Setter and images were formed with a 1074 nm YAG laser at 9 wats (150 mj / square centimeter on the surface of the plate). The silicone coating was worn cleanly with little or no visible residue in the worn area. EXAMPLE 4 Two anodized and granulated brush aluminum substrates were used (EX-140 and EX-147 of Table 1). The uncoated aluminum plates were placed in the Gerber Crescent 42T Píate Image Setter and exposed in the image direction with the YAG laser at 9, 7 and 5 wats. A permanent visible image was left after exposure on the surface of anodized aluminum granulated by brush. The change caused by the YAG laser produced enough contrast so that the visible image could be detected up to 5 watts. Example 5 An aluminum substrate was prepared as in Example 3 except that a subsequent treatment of polyvinyl phosphonic acid was applied to the anodized surface by brush. Thus prepared, the substrate was coated with a solution of Dow Corning Silicone Resin 6-2230 at a coating weight of 150 mg / square foot. Images were formed on the plate with a YAG laser at 9 wats as in Example 1. The areas where images were formed were worn cleanly leaving little or no residue. Example 6 An anodized aluminum substrate was prepared by brush as in Example 3. A sub-coating of gum arabic (3.5%) was applied with a Meyer # 1 applicator rod. Referring to the Figure 4, this subcoat 15 appears between the oxide 14 of the top coating 16. The coating is dried in an oven at 90 ° C for 1 minute. The weight of the coating mg / square foot was determined gravimetrically. A second coating (top coat) of Dow Corning 6-2230 applied at 150 mg / square foot was coated on the subcoat and dried at 90 ° C for 2 minutes. The brush-anodized coated plate, as described, was placed in a Gerber Crescent 42T Plate Image Setter. Images (background) were formed on the plate with a 1074 nm YAG laser at 9 watts of power. The resulting wear produced a clear and clean image of a standard GATF-quality controlled lens. This quality controlled objective contains 200 Ipi of halftones, 0.5% of light points, and 99.5% of shadow points, along with a positive pixel and negative concentric circular lenses. The plate with the images was placed in a Ryobi Duplicating Press with a development step. 200 clean copies were produced showing a perfect resolution of all the images, including a positive pixel and a negative circle. Example 7 The following positive-action light-sensitive coating formula was prepared: Arcosolve PM 42.86% Ethanol 21.34" P-cresol resin of 1,1-naphthoquinone-Diazide [2] -5-sulfonyloxy 9.26% cresol resin 20.70% Resin of t-butylphenolformaldehyde 0.36, Phenolformaldehyde resin 4.76 ', Blue coloring 0.76 ' BYK 344 0.00, The above coating was applied to an anodized aluminum substrate (EX-147, Table 1) at a dry coating weight of 140 mg per square foot. Images were formed on the plate prepared in this way in a Gerber Crescent 42T Piato Image Setter at a laser energy of 6.5 watts. The coating was worn away in the areas where the laser formed the images on the anodized aluminum substrate. The plate was developed with a commercially available Fuji DP-4 developer to a dilution of one part of developer per 8 parts of water. After the development, the areas of the plate where the images were formed by laser were free of coating, while the areas written without laser of the plate kept the coating. Comparative Example 8 The coating formula of Example 7 was applied to an anodized aluminum substrate (Delta, Table 1) at a dry coating weight of 14 mg / square foot. Images were formed on the plate thus prepared in the same manner as in Example 7. In this case, no coating wear was observed in the areas where the laser hit the surface of the plate. When it was revealed in the same manner as the plate in Example 7 there was no removal of the coating in the laser-written areas of the plate; The entire plate remained uniformly coated.

Example 9 An aluminum substrate was degreased, granulated by brushing and nodulated in the network form. The granulization was achieved by three passes through a series of eight nylon cylindrical brushes that rotated at 750 rpm. The speed of the network was 80 feet per minute. The granulization medium was non-molten aluminum oxide (calcined alumina). After granulation, the network was anodized in sulfuric acid to an oxide coating weight of 0.5 mg / square foot, rinsed, dried and rolled up. The anodized and granulized roll was then placed in a roll coating line equipped with an extrusion coating head. Positive work, the UV sensitive coating of example 7 was applied to a coating weight of 20 mg / square foot. The coated product was cut into single-sheet plates sized to accommodate a Goss Community press and placed in a Gerber Crescent 42T Plate Image Setter equipped with a 10-watt YAG laser that delivers 7 watts of power to the plate surface. A newspaper data file containing the digital data required to produce - a set of four color separations needed to print a color ad was used. The laser scanned the plates at 150 Hz, 2540 dpi with a dot size of 12 microns. The tracking was done in the positive mode, that is, the second plane was removed. The plates with formed images were developed in a modified positive processor set at 5 feet per minute. The modification consisted of a rinsing / brushing section followed by a UV exposure of 25 mj / cm2 before entering the positive processor. The developing station of the positive processor contained a standard developer consisting of an alkali metal silicate and a sodium hydroxide. The pH was approximately 12.5. The plates were rinsed and dried. The processed plates were placed in a four-color Goss Community press located in a commercial newspaper facility. One hundred and twenty five thousand color prints of excellent quality were produced. Example 10 Rotary brush granulated samples were prepared for the following types of flat metal sheet: Terne (Pb / Sm alloy) coated steel Soft carbon steel Galvanized steel Tin plated steel Zinc For each sample, the granulation was carried out by a single pass through a series of eight cylindrical nylon brushes that rotate at 750 rmp. The speed through the granulator was 12 feet / minute. The granulating suspension contained unmelted aluminum oxide (calcined alumina). One of the eroded samples of each type was then coated by means of a Meyer applicator rod with a light sensitive positive working coating applied to a coating weight of 20 mg per square foot. The coating was the same light-sensitive coating with positive action as in Example 7. Images were etched on the uncoated and coated sheets in a Gerber Crescent 42T Píate Image Thermal as in Example 9. The samples coated with formed images they were revealed as in Example 9. All the coated plates were worn with a good resolution. All eroded samples without coating, with the exception of mild carbon steel, showed evidence of low-contrast visible image formation as a result of selective laser writing. Example 11 An aluminum substrate was degreased, granulated by brush and anodized in the network form. The granulization was achieved by a single pass through a series of 8 cylindrical nylon brushes that rotate at 750 rpm. The speed of the network was 23 feet per minute. The granulation medium was aluminum oxide (not molten) calcined alumina). After the granulation, the network was anodized in sulfuric acid to an oxide coating weight of 0.5 milligrams per square inch, rinsed, dried, and rolled. A sample of this aluminum network was subsequently vacuum metallized with aluminum at a coating thickness of approximately 600 Angstroms. The metallized surface in this way had a relatively reflective visual appearance. Images were formed on the sample in a Gerber Crescent 42T Píate Imager Thermal as in the Example 9. An image was formed as a result of selective writing by the laser. In areas where the laser did not hit the plate, the reflective visual appearance of the metallized layer was lost, and the underlying dark oxide layer was revealed. Example 12 An anodized aluminum substrate by rotating brush was prepared as in Example 11 and coated with a positive-acting coating as in Example 7. A second coating of a cross-polysiloxane polymer (following formulation) was applied over the positive action coating at a coating weight of 150-200 mg / ft2 and dried in a 150CC oven for two minutes.

Coating formulation G PS185 (United Chem Tech) 5. 0 PC-072 (United Chem Tech) 0. 05 PS123 (United Chem Tech) 0. 15 Methylpentinol 0. 05 Hexano 24:. 75 The plates coated twice were placed in a Gerber Crescent 42T Píate Image Setter equipped with a YAG laser of 1.10 wats. The plates were screened at 150 Hz, 2540 dpi with a dot size of 10 microns. After the tracking it was observed that both coatings in the areas exposed to the laser beam were worn out. A soft carving with a soft brush or cloth easily removed the worn residue. In this embodiment, the positive action coating wears directly from the surface of the plate which also removes the corresponding area of the underlying cross-linked polymer. The worn plates were placed in a direct driographic imaging press without Heidelberg water which prints with a hi tack ink. The non-worn areas of the plate have an ink-repellent polysiloxane surface while the image is retransffered from those areas of the plate exposed by the wear by the laser. In this way, a positive action coating is used to make a negative work plate for driographic printing. Example 13 Example 12 was repeated using the following polysiloxane as the second coating: Grade Coating Formulation SFR750 (PPG) 7.5 SF201 (PPG) 3.5 XL-1 (PPG) 5.0 2-7131 (Dow Corning) 0.5 Dibutyl Tin Dilaurate 2.0 Acetic Acid 3.5 Hexane 28.0 The plates coated twice were placed in a Gerber Crescent 42T Píate Image Setter equipped with a 10-watt YAG laser. The plates were screened at 150 Hz, 2540 dpi, with a spot size of 10 microns. After the scanning it was observed that both coatings in the areas exposed to the laser beam were worn out. Gentle carving with a soft brush or cloth easily removed the worn residue. In this embodiment, the positively acting coating directly wears off the surface of the plate which also removes the corresponding area of the underlying cross-linked polymer. The worn plates are placed in a Heidelberg driographic direct image press without water, which prints with a hi-tack ink. The non-worn areas of the plate have an ink-repellent polysiloxane surface while the image is transferred from those areas of the plate exposed to laser wear. In this way, a positive action coating is used to be a negative work plate for driographic printing.

Claims (64)

1. CLAIMS 1. A printing plate characterized in that it comprises: (a) an anodically oxidized aluminum substrate which has been treated before anodizing it so that the anodically oxidized substrate can be etched with visible images by selective exposure to a laser infrared; and (b) a coating which is transparent to infrared laser radiation on the substrate, which coating can be abraded from the substrate when the substrate collides with the infrared laser radiation after passing through the transparent coating to the laser.
2. 2. The printing plate according to claim 1, characterized in that the substrate is granulized by brush before being anodized.
3. 3. The printing plate according to claim 2, characterized in that the anodic oxidation is carried out after the brush granulation without etching or other treatment before or during anodizing which prevents the ability of the substrate to form visible images by Selective exposure to an infrared laser.
4. 4. The printing plate according to claim 1, characterized in that the wear-resistant coating is present on the surface in an amount of 50-500 mg / ft2.
5. 5. The printing plate according to claim 1, characterized in that the coating is a silicone polymer.
6. 6. The printing plate according to claim 1, characterized in that the coating is oleophilic.
7. The printing plate according to claim 1, characterized in that the coating comprises a light-sensitive coating with positive action.
8. 8. The printing plate according to claim 1, characterized in that the coating comprises a phenolic coating sensitive to light of positive action.
9. 9. The printing plate according to claim 1, characterized in that it includes a second coating which is transparent to the radiation of the infrared laser on the coating.
10. 10. The printing plate according to claim 7, characterized in that it is suitable for the driographic printing which includes a second coating repellent to the tape on the positive action coating.
11. 11. The printing plate according to claim 10, characterized in that the second coating is a non-abradable silicone polymer.
12. 12. A printing plate characterized in that it comprises: (a) an aluminum substrate which has been treated so that the substrate can be recorded with visible images by selective exposure to an infrared laser; and (b) a coating which is transparent to the infrared laser radiation on the surface, which can be abraded from the surface where the surface collides with the infrared laser radiation after passing through the transparent coating to the laser.
13. 13. The printing plate according to claim 12, characterized in that the substrate is granulated by a rotating brush.
14. 14. The printing plate according to claim 12, characterized in that the wear-resistant coating is present on the surface in an amount of 50-500 mg / ft2.
15. 15. The printing plate according to claim 12, characterized in that the coating is a silicone polymer.
16. 16. The printing plate according to claim 12, characterized in that the coating is oleophilic.
17. 17. The printing plate according to claim 12, characterized in that the coating comprises a light-sensitive coating with positive action.
18. 18. The printing plate according to claim 17, characterized in that the coating comprises a positive-effect light-sensitive phenolic coating.
19. 19. The printing plate according to claim 12, characterized in that it includes a second coating which is transparent to the radiation of the infrared laser on the coating.
20. 20. The printing plate according to claim 12, characterized in that it is suitable for the driographic printing which includes a second coating repellent to the tape on the positive action coating.
21. 21. The printing plate according to claim 20, characterized in that the second coating is a non-abradable silicone polymer.
22. 22. A printing plate substrate characterized in that it comprises an aluminum substrate in which visible images can be formed by selective exposure to an infrared laser.
23. 23. The printing plate according to claim 22, characterized in that the substrate is granulated by a rotating brush.
24. 24. The printing plate substrate characterized in that it comprises an anodically oxidized aluminum substrate has been treated before being anodized so that the anodically oxidized substrate can be etched with visible images by selective exposure to an infrared laser.
25. 25. The substrate printing plate according to claim 24, characterized in that the substrate is granulized by brush before being anodized.
26. The printing plate substrate according to claim 24, characterized in that the anodic oxidation is carried out after the brush granulation without the recording or other treatment before or during the anodizing which could deteriorate the capacity of the substrate to form visible images by selective exposure to an infrared laser.
27. 27. A method for preparing a printing plate characterized in that it comprises: (a) treating an aluminum substrate to form a surface on which visible images can be formed by selective exposure to an infrared laser; (b) anodizing the surface to form an anodic aluminum oxide layer; (c) coating the oxide layer with a material which is transparent to the radiation of the infrared laser which can be abraded from the layer where the layer collides with the infrared laser radiation.
28. 28. The printing plate according to claim 27, characterized in that the substrate is granulated by a rotating brush.
29. 29. The method according to claim 27, characterized in that the abradable coating is present on the surface in an amount of 50-500 mg / ft2.
30. 30. The method according to claim 27, characterized in that the coating is a silicone polymer.
31. 31. The method according to claim 27, characterized in that the coating is oleophilic.
32. 32. The method according to claim 27, characterized in that the coating comprises a light-sensitive coating with positive action.
33. 33. The method according to claim 27, characterized in that the coating comprises a phenolic coating sensitive to light of positive action.
34. 34. The method according to claim 27, characterized in that it includes a second coating which is transparent to the radiation of the infrared laser on the coating.
35. 35. The method according to claim 27, characterized in that it is suitable for the driographic printing that includes a second coating repellent to the tape on the coating.
36. 36. The method according to claim 35, characterized in that the second coating is a non-wear-resistant silicone polymer.
37. 37. A method for preparing a printing plate characterized in that it comprises: (a) forming images on the printing plate of claim 6 with an infrared laser to remove the light-sensitive coating of positive action from the second plane of the plate; (b) exposing the plate with laser imaging of step (a) to sufficient UV light to solubilize any remaining coating in the second plane without substantially affecting the image on the plate; and (c) applying a solvent for the coating solubilized in the exposed blanket plate.
38. 38. A printing plate characterized in that it comprises a metal substrate that has been treated so that the substrate can be etched with visible images by selective exposure to an infrared laser having a coating transparent to the infrared laser radiation which can be wear of the same where the substrate collides with the infrared laser radiation.
39. 39. The printing plate according to claim 38, characterized in that the substrate is granulated by a rotating brush.
40. 40. The printing plate according to claim 38, characterized in that the abradable coating is present on the surface in an amount of 50-500 mg / ft2.
41. 41. The printing plate according to claim 38, characterized in that the coating is oleophilic.
42. 42. The printing plate according to claim 38, characterized in that the coating comprises a phenolic coating sensitive to light of positive action.
43. 43. The printing plate according to claim 38, characterized in that it includes a second coating which is transparent to the radiation of the infrared laser on the coating.
44. 44. The printing plate according to claim 38, characterized in that it is suitable for the driographic printing including a second coating repellent to the tape on the positive action coating.
45. 45. The printing plate according to claim 44, characterized in that the second coating is a non-abradable silicone polymer.
46. 46. The printing plate according to claim 38, characterized in that the metal substrate is selected from the group of aluminum, titanium, tin, zinc, lead, iron and alloys thereof.
47. 47. The printing plate according to claim 38, characterized in that the metal substrate is steel coated with a metal of the group of tin, zinc, lead and alloys thereof.
48. 48. The printing plate according to claim 38, characterized in that the metal substrate is anodically oxidized zinc, steel or titanium coated with zinc.
49. 49. The printing plate according to claim 38, characterized in that the coating is a silicone polymer.
50. 50. The printing plate according to claim 38, characterized in that the coating comprises a light-sensitive coating with positive action.
51. 51. A printing plate comprising a metal substrate having a coating transparent to the infrared laser radiation of the substrate has been treated before being coated so that the coating can be abraded from the substrate when the substrate collides with the radiation of the substrate. infrared laser after passing through the transparent coating to the laser.
52. 52. The printing plate according to claim 51, characterized in that the substrate is granulated by a rotating brush. .
53. 53. The printing plate according to claim 51, characterized in that the metal substrate is selected from the group of aluminum, titanium, tin, zinc, lead, iron and alloys thereof.
54. 54. The printing plate according to claim 51, characterized in that the metal substrate is steel coated with a metal of the group of tin, zinc, lead and alloys thereof.
55. 55. A printing member characterized in that it comprises a metal cylinder having a coating transparent to the radiation of the infrared laser. The cylinder has been treated before being coated so that the coating can be abraded from the substrate when the substrate collides with the radiation of the infrared laser after going through the transparent coating to the laser.
56. 56. The printing plate according to claim 1, characterized in that the anodically oxidized surface is metallized in vacuum before being coated.
57. 57. The printing plate according to claim 12, characterized in that the eroded surface is metallized under vacuum before being coated.
58. 58. The method according to claim 27, characterized in that the anodized surface of step (b) is metallized in vacuum before being coated in step (c).
59. 59. The printing plate according to claim 38, characterized in that the substrate is vacuum metallized before coating.
60. 60. The printing plate according to claim 51, characterized in that the substrate is vacuum metallized before coating.
61. 61. Bifunctional surface for a printing plate comprising a surface and a wear coating on it, the coating is transparent to the infrared laser radiation, the surface has been treated before being coated so that it is capable of absorbing the radiation of infrared laser to abrade the coating after the laser radiation passes through the coating and thereby presenting a surface that participates in the printing where the coating is worn.
62. 62. Printing plate comprising: a) a treated aluminum substrate for embedding particles on its surface, the particles have a low thermal conductivity in relation to aluminum and a higher hardness than aluminum; b) the substrate when selectively exposed to an infrared laser produces localized casting of the aluminum on the surface of the substrate resulting in a visible image on the substrate; c) a coating that is transparent to infrared laser radiation on the substrate, coating that can be abraded from the substrate when the substrate collides with the infrared laser radiation after passing through the transparent coating to the laser.
63. 63. The printing plate according to claim 62, characterized in that the particles are incrusted by scraping with rotating brush the substrate.
64. 64. The printing plate according to claim 62, characterized in that the substrate is oxidized anodically after being treated to embed the particles.