CA2154012C - An erasable printing plate and a process and apparatus for erasing and regenerating the printing plate - Google Patents
An erasable printing plate and a process and apparatus for erasing and regenerating the printing plateInfo
- Publication number
- CA2154012C CA2154012C CA002154012A CA2154012A CA2154012C CA 2154012 C CA2154012 C CA 2154012C CA 002154012 A CA002154012 A CA 002154012A CA 2154012 A CA2154012 A CA 2154012A CA 2154012 C CA2154012 C CA 2154012C
- Authority
- CA
- Canada
- Prior art keywords
- printing plate
- plate
- printing
- roller
- cleaning
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
- B41C1/00—Forme preparation
- B41C1/10—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme
- B41C1/1058—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme by providing a magnetic pattern, a ferroelectric pattern or a semiconductive pattern, e.g. by electrophotography
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
- B41C1/00—Forme preparation
- B41C1/10—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme
- B41C1/1066—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme by spraying with powders, by using a nozzle, e.g. an ink jet system, by fusing a previously coated powder, e.g. with a laser
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM
- B41N1/00—Printing plates or foils; Materials therefor
- B41N1/006—Printing plates or foils; Materials therefor made entirely of inorganic materials other than natural stone or metals, e.g. ceramics, carbide materials, ferroelectric materials
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41P—INDEXING SCHEME RELATING TO PRINTING, LINING MACHINES, TYPEWRITERS, AND TO STAMPS
- B41P2227/00—Mounting or handling printing plates; Forming printing surfaces in situ
- B41P2227/70—Forming the printing surface directly on the form cylinder
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- Inorganic Chemistry (AREA)
- Printing Plates And Materials Therefor (AREA)
- Inking, Control Or Cleaning Of Printing Machines (AREA)
- Rotary Presses (AREA)
Abstract
A printing plate which can be repeatedly directly provided with an image and erased and is suitable for a wet offset printing method. The printing plate has a smooth and pore-free surface which is hydrophilic or can be hydrophilized after being provided with an image. The printing plate contains no strong microdipoles and consists of a ceramic, a glass or a metal, in particular of a metal alloy. An erasing and hydrophilizing apparatus preferably integrated in the printing press, repeatedly erases and prepares, i.e. rehydrophilizes, the printing plate for a further image-providing and printing process.
Description
215~012 AN ERASABLE PRINTING PLATE AND A PROCESS AND
APPARATUS FOR ERASING AND REGENERATING
THE PRINTING PLATE
TECHNICAL FIELD
The lnvention relates to an erasable printing plate and to a process and an apparatus for erasing and regenerating the printing plate.
BACKGROUND ART
A printing plate suitable for the wet offset method is disclosed in DE 42 35 242 8. This printing plate has strong microdipoles at least in its outer layer, and its surface is hydrophobic. After application of covering material corresponding to an image to be printed, the non-image parts are hydrophilized by a hydrophilizing agent. It is true that these printing plates have the advantage that they can readily be regenerated, i.e. after completion of a printing process they can be erased in a simple manner and provided with further images. However, these printing plates have the disadvantage that it is expensive to produce them.
Regeneration processes which are suitable for smooth as well as rough, porous printing plates of ceramic, glass or anodized aluminum are disclosed in DE 41 23 959 C 1. The disadvantage of these regeneration/erasing processes is that they are technically relatively complicated and expensive to carry out.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a printing plate which can be directly provided with images and repeatedly erased and which has the advantage of simpler production compared with known printing plates.
215~012 Pursuant to this object, one aspect of the present invention resides in a printing plate which has a pore-free and smooth surface with a roughness Ra of less than 1 ~m. The smooth surface is hydrophilic or can be hydrophilized and plate material contains no strong microdipoles.
It is a further object of the invention to provide a process for repeatedly erasing and regenerating such a printing plate, which can be carried out within the printing press, without removal of the plate cylinder or of the printing plate.
Pursuant to this object, another aspect of the present invention resides in a process for erasing a print image on the printing plate, which process includes pressing a cleaning cloth against the surface of the printing plate using a pressure roller while the plate cylinder on which the printing plate is mounted slowly rotates. The cleaning cloth is unwound from a feed roller and is wound onto a wind-up roller either in a step wise manner or continuously. The pressure roller permits the contact pressure of the cleaning cloth against the plate cylinder to be varied. Additionally, nozzles supply cleaning solutions directly to the surface of the printing plate or to the cleaning cloth.
Another aspect of the present invention resides in a printing press which includes a plate cylinder on which the printing plate is mounted, and still further includes an erasing and hydrophilizing apparatus positionable at the plate cylinder for cleaning the printing plate and hydrophilizing the surface thereof.
According to the invention, there is provided a printing plate a printing plate which can be directly provided with an image and erased and is suitable for wet offset printing, the printing plate comprising a pore-free and smooth surface with a roughness Ra of <
215~012 1 um, which surface is at least one of hydrophilic and hydrophilizable, the plate also contains no strong microdipoles.
The invention further provides a printing press comprising a printing press. The printing press comprises a plate cylinder; a printing plate mounted on the plate cylinder; and erasing and hydrophilizing means arranged to be operatively positionable at the plate cylinder for cleaning the printing plate and hydrophilizing a surface of the printing plate.
According to the invention, there is also provided a process for erasing a print image from a printing plate mounted on a plate cylinder, comprising the steps of: pressing a cleaning cloth against a surface of the printing plate using a pressure roller while the plate cylinder slowly rotates; unwinding the cleaning cloth from a feed roller and winding the cleaning cloth onto a wind-up roller one of continuously and step wise; and applying a cleaning solution via nozzles one of directly to the surface of the printing plate and to the cleaning cloth.
For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The single figure shows, in cross-section, a printing unit having an apparatus according to the invention for erasing and regenerating the printing plate according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
For a printing plate to be capable of being 21~ ~101~
readily erased, it must be smooth and pore-free.
Hence, it must not contain cavities, at least not in its surface, and must not be rough, so that no mechanical anchoring occurs between the surface and the image-producing material, printing ink or dirt, which can no longer be removed once contained in the surface cavities. To accomplish this the surface roughness Ra must be < 1 um. To ensure that the printing plates are suitable for the wet offset method, their surface must be either hydrophilic or easily capable of being rendered hydrophilic. The printing plate is hydrophilized by spraying a hydrophilizing agent, such as a plate cleaner, onto it, for example from nozzles. The hydrophilic character of the surface must be capable of being restored even after thermal stress, i.e. after a thermal fixing step for material applied imagewise.
Hence, it must at most become reversibly weaker or disappear reversibly.
Suitable materials for the production of such printing plates are, for example, ceramics. The plates can be are prepared by the sol-gel process, a PVD or a CVD process, in a thermal spray process, for example the plasma spray process, or by a sinter process. The ceramic must then be ground as smooth as glass, i.e.
it may only have a roughness Ra < 0.3 um. If the printing plates produced in one of the stated processes are still not pore-free, they are subsequently sealed.
Ceramic printing plates contain, for example, alumina, aluminum silicate (mullite), zirconium silicate or zirconium oxide. It is particularly advantageous if the hydrophilic character of a ceramic printing plate not only is achieved by hydrophilizing the surface but is a volume property of the ceramic layer.
APPARATUS FOR ERASING AND REGENERATING
THE PRINTING PLATE
TECHNICAL FIELD
The lnvention relates to an erasable printing plate and to a process and an apparatus for erasing and regenerating the printing plate.
BACKGROUND ART
A printing plate suitable for the wet offset method is disclosed in DE 42 35 242 8. This printing plate has strong microdipoles at least in its outer layer, and its surface is hydrophobic. After application of covering material corresponding to an image to be printed, the non-image parts are hydrophilized by a hydrophilizing agent. It is true that these printing plates have the advantage that they can readily be regenerated, i.e. after completion of a printing process they can be erased in a simple manner and provided with further images. However, these printing plates have the disadvantage that it is expensive to produce them.
Regeneration processes which are suitable for smooth as well as rough, porous printing plates of ceramic, glass or anodized aluminum are disclosed in DE 41 23 959 C 1. The disadvantage of these regeneration/erasing processes is that they are technically relatively complicated and expensive to carry out.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a printing plate which can be directly provided with images and repeatedly erased and which has the advantage of simpler production compared with known printing plates.
215~012 Pursuant to this object, one aspect of the present invention resides in a printing plate which has a pore-free and smooth surface with a roughness Ra of less than 1 ~m. The smooth surface is hydrophilic or can be hydrophilized and plate material contains no strong microdipoles.
It is a further object of the invention to provide a process for repeatedly erasing and regenerating such a printing plate, which can be carried out within the printing press, without removal of the plate cylinder or of the printing plate.
Pursuant to this object, another aspect of the present invention resides in a process for erasing a print image on the printing plate, which process includes pressing a cleaning cloth against the surface of the printing plate using a pressure roller while the plate cylinder on which the printing plate is mounted slowly rotates. The cleaning cloth is unwound from a feed roller and is wound onto a wind-up roller either in a step wise manner or continuously. The pressure roller permits the contact pressure of the cleaning cloth against the plate cylinder to be varied. Additionally, nozzles supply cleaning solutions directly to the surface of the printing plate or to the cleaning cloth.
Another aspect of the present invention resides in a printing press which includes a plate cylinder on which the printing plate is mounted, and still further includes an erasing and hydrophilizing apparatus positionable at the plate cylinder for cleaning the printing plate and hydrophilizing the surface thereof.
According to the invention, there is provided a printing plate a printing plate which can be directly provided with an image and erased and is suitable for wet offset printing, the printing plate comprising a pore-free and smooth surface with a roughness Ra of <
215~012 1 um, which surface is at least one of hydrophilic and hydrophilizable, the plate also contains no strong microdipoles.
The invention further provides a printing press comprising a printing press. The printing press comprises a plate cylinder; a printing plate mounted on the plate cylinder; and erasing and hydrophilizing means arranged to be operatively positionable at the plate cylinder for cleaning the printing plate and hydrophilizing a surface of the printing plate.
According to the invention, there is also provided a process for erasing a print image from a printing plate mounted on a plate cylinder, comprising the steps of: pressing a cleaning cloth against a surface of the printing plate using a pressure roller while the plate cylinder slowly rotates; unwinding the cleaning cloth from a feed roller and winding the cleaning cloth onto a wind-up roller one of continuously and step wise; and applying a cleaning solution via nozzles one of directly to the surface of the printing plate and to the cleaning cloth.
For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The single figure shows, in cross-section, a printing unit having an apparatus according to the invention for erasing and regenerating the printing plate according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
For a printing plate to be capable of being 21~ ~101~
readily erased, it must be smooth and pore-free.
Hence, it must not contain cavities, at least not in its surface, and must not be rough, so that no mechanical anchoring occurs between the surface and the image-producing material, printing ink or dirt, which can no longer be removed once contained in the surface cavities. To accomplish this the surface roughness Ra must be < 1 um. To ensure that the printing plates are suitable for the wet offset method, their surface must be either hydrophilic or easily capable of being rendered hydrophilic. The printing plate is hydrophilized by spraying a hydrophilizing agent, such as a plate cleaner, onto it, for example from nozzles. The hydrophilic character of the surface must be capable of being restored even after thermal stress, i.e. after a thermal fixing step for material applied imagewise.
Hence, it must at most become reversibly weaker or disappear reversibly.
Suitable materials for the production of such printing plates are, for example, ceramics. The plates can be are prepared by the sol-gel process, a PVD or a CVD process, in a thermal spray process, for example the plasma spray process, or by a sinter process. The ceramic must then be ground as smooth as glass, i.e.
it may only have a roughness Ra < 0.3 um. If the printing plates produced in one of the stated processes are still not pore-free, they are subsequently sealed.
Ceramic printing plates contain, for example, alumina, aluminum silicate (mullite), zirconium silicate or zirconium oxide. It is particularly advantageous if the hydrophilic character of a ceramic printing plate not only is achieved by hydrophilizing the surface but is a volume property of the ceramic layer.
2~ 54012 Instead of being produced from ceramic, printing plates having a smooth surface may also be produced from glass, preferably from a borosilicate-based glass which is resistant to chemicals and to heat.
Other materials for the production of the printing plates are metals, among which alloys having a good microstructural stability and high resistance to oxidation even during thermal cycling are particularly suitable. When used as printing plates, the metals have a surface smooth as rolled material with a roughness Ra < 0.2 ~m.
Nickel chromium steels are particularly suitable for producing printing plates. Nickel-chromium-iron alloys and nickel-chromium-molybdenum alloys are preferably used, in particular the alloys obtainable from the company Heynes International Incorporated, Kokomo, USA, under the material numbers 2.4665 and 2.4819, 2.4602, 2.4636 and 2.4638, respectively. Other very suitable nickel-chromium-molybdenum and nickel-chromium-iron alloys are the alloys obtainable under the material numbers 2.4856 and 2.4851 from the company Huntington Alloy Product Division, Huntington, USA. The common feature of all these alloys is that, like the other alloys not named more specifically here, they have good resistance to the thermal cycling caused by the thermal fixing as well as good resistance to oxidation.
After the end of the printing process, such a printing plate which has been directly provided with an image and consists of one of the above-mentioned materials, a ceramic, a glass, or a metal, or at least has a surface layer of one of these materials, can be erased within the printing press in the manner described next. First, the printing ink residues and the coating applied imagewise are removed, for example 2ls~l2 wiped off, by means of a cleaning agent. The cleaning agent is a solvent or solvent mixture that contains no solid components. In order to be able to remove even final and slight residues of the coating applied imagewise to the printing plate, which residues otherwise cause so-called ghost images, the surface of the printing plate is then mechanically rubbed. A
polish-containing cleaning agent, for example a plate cleaner, as generally used for cleaning printing plates, serves for this purpose. The plate cleaner is then removed, for example with water, and the printing plate is rendered hydrophobic again by wetting with a solvent, in order to prepare it for a further direct-image-providing step. After provision of an image and fixing, the printing plate is hydrophilized again, as also disclosed, for example, in DE 42 35 242 C 1, unless the material of the printing plate already has a hydrophilic surface and it is therefore sufficient if the non-image parts are hydrophilized again only by the fountain solution during the printing process.
The apparatus shown in the figure is used both for erasing and for hydrophilizing and for fixing the printing plate described above, which is directly provided with an image, and other printing plates, as disclosed, for example, according to DE 41 23 959 C 1 or DE 36 33 758 A 1. The fixing step comprises heating the printing plate provided with an image to a surface temperature between 170C and 210C by means of a drier 7. Alternatively, the printing plate can be heated either inductively or by an infrared lamp. In other fixing processes, W radiation or electron beams are used. It is also possible to cure the printing plates by suitable chemicals, for example merely by moisture.
The erasing and hydrophilizing apparatus is installed as a fixed unit in a printing unit of an 21~012 offset printing press and is arranged on the circumference of a plate cylinder 1 having a printing plate 2 which can be directly provided with an image.
A rubber blanket cylinder 3 for transferring the print image to a print medium, such as the print medium web 17 shown here, and rollers 4, 5 of an inking unit or of a damping unit rest against the plate cylinder 1.
An image-providing unit (not shown here) is likewise arranged on the circumference of the plate cylinder 1, for direct provision of an image.
The erasing and hydrophilizing apparatus has a cleaning apparatus 6 and the drier 7, which can be fed toward the printing plate 2 and moved away from it again. The cleaning apparatus 6 operates by means of a cleaning cloth or cleaning fleece 8, which passes from a feed roller 9 via a pressure roller 10 which presses the fleece 8 against the printing plate 2, and is then wound onto a wind-up roller 11.
The pressure roller 10 is in turn rotatably mounted in a vibrating head 12. The vibrating head 12 is pressed against the printing plate 2 by means of a pressure cylinder 13. Nozzles 14, which are present in front of the cleaning apparatus 6 in the direction of rotation of the plate cylinder 1, can apply a cleaning liquid or a cleaning paste, a hydrophilizing agent, for example a plate cleaner, or another agent which serves either for erasing the printed image applied to the printing plate 2 and for removing printing ink residues or for hydrophilizing the surface of the printing plate 2, to the printing plate. This agent, together with the dirt which it removes, can be taken up by the cleaning cloth 8 if the pressure cylinder 13 presses the pressure roller 10 against the printing plate 2 and the cleaning cloth 8 is moved past the printing plate 2. The nozzles 14 can preferably be adjusted with regard to their angle to spray the agent 215~012 either directly onto the printing plate 2 or onto the cleaning cloth 8. The pressure roller 10 is, for example, rubber-coated. The cleaning cloth 8 is wound either in portions or continuously from the feed roller 9 onto the wind-up roller 11. Preferably, the pressure with which the cleaning cloth 8 is pressed against the printing plate 2 can also be varied.
The printing plate 2 cleaned by the cleaning apparatus 6 can then be dried by the drier 7, with hot air via a hot air supply apparatus 15. The hot air flows subsequently, when it contains, for example, solvent residues, back through an extraction apparatus 16.
The erasing and hydrophilizing apparatus can, for example, be positioned alternately at the plate cylinder 1 or at the rubber blanket cylinder 3 if it is also intended to clean the rubber blanket by means of the erasing and hydrophilizing apparatus.
In another embodiment, the erasing and hydrophilizing apparatus is located outside the printing press, in order there to clean only printing plates 2 or rubber blankets.
The cleaning solutions used are solvents for removing the printing ink residues and the polymer layer applied imagewise, or other cleaning agents which contain abrasive media, such as, for example, some of the plate cleaners conventionally used in the graphics industry, or water for removing abrasive residues. The cleaning agents can be used one after the other in any desired sequence or in a changing sequence. Also, the printing plate surface to be erased can also be rubbed off with a dry cleaning cloth after or between the individual cleaning steps.
In order to increase the efficiency of cleaning agents containing abrasive media, the cleaning cloth 8 preferably moves in a manner which changes.
215~012 The invention provides a printing plate 2 which can be repeatedly directly provided with an image and erased and is suitable for a wet offset printing method. I-t has a smooth and pore-free surface which is hydrophilic or can be hydrophilized after being provided with an image. The printing plate 2 contains no strong microdipoles and consists of a ceramic, a glass or a metal, in particular of a metal alloy. By means of an erasing and hydrophilizing apparatus 6, 7 preferably integrated in the printing press, the printing plate 2 can be repeatedly erased and prepared, i.e. rehydrophilized, for a further image-providing and printing process.
The invention is not limited by the embodiments described above which are presented as examples only but can be modified in various ways within the scope of protection defined by the appended patent claims.
Other materials for the production of the printing plates are metals, among which alloys having a good microstructural stability and high resistance to oxidation even during thermal cycling are particularly suitable. When used as printing plates, the metals have a surface smooth as rolled material with a roughness Ra < 0.2 ~m.
Nickel chromium steels are particularly suitable for producing printing plates. Nickel-chromium-iron alloys and nickel-chromium-molybdenum alloys are preferably used, in particular the alloys obtainable from the company Heynes International Incorporated, Kokomo, USA, under the material numbers 2.4665 and 2.4819, 2.4602, 2.4636 and 2.4638, respectively. Other very suitable nickel-chromium-molybdenum and nickel-chromium-iron alloys are the alloys obtainable under the material numbers 2.4856 and 2.4851 from the company Huntington Alloy Product Division, Huntington, USA. The common feature of all these alloys is that, like the other alloys not named more specifically here, they have good resistance to the thermal cycling caused by the thermal fixing as well as good resistance to oxidation.
After the end of the printing process, such a printing plate which has been directly provided with an image and consists of one of the above-mentioned materials, a ceramic, a glass, or a metal, or at least has a surface layer of one of these materials, can be erased within the printing press in the manner described next. First, the printing ink residues and the coating applied imagewise are removed, for example 2ls~l2 wiped off, by means of a cleaning agent. The cleaning agent is a solvent or solvent mixture that contains no solid components. In order to be able to remove even final and slight residues of the coating applied imagewise to the printing plate, which residues otherwise cause so-called ghost images, the surface of the printing plate is then mechanically rubbed. A
polish-containing cleaning agent, for example a plate cleaner, as generally used for cleaning printing plates, serves for this purpose. The plate cleaner is then removed, for example with water, and the printing plate is rendered hydrophobic again by wetting with a solvent, in order to prepare it for a further direct-image-providing step. After provision of an image and fixing, the printing plate is hydrophilized again, as also disclosed, for example, in DE 42 35 242 C 1, unless the material of the printing plate already has a hydrophilic surface and it is therefore sufficient if the non-image parts are hydrophilized again only by the fountain solution during the printing process.
The apparatus shown in the figure is used both for erasing and for hydrophilizing and for fixing the printing plate described above, which is directly provided with an image, and other printing plates, as disclosed, for example, according to DE 41 23 959 C 1 or DE 36 33 758 A 1. The fixing step comprises heating the printing plate provided with an image to a surface temperature between 170C and 210C by means of a drier 7. Alternatively, the printing plate can be heated either inductively or by an infrared lamp. In other fixing processes, W radiation or electron beams are used. It is also possible to cure the printing plates by suitable chemicals, for example merely by moisture.
The erasing and hydrophilizing apparatus is installed as a fixed unit in a printing unit of an 21~012 offset printing press and is arranged on the circumference of a plate cylinder 1 having a printing plate 2 which can be directly provided with an image.
A rubber blanket cylinder 3 for transferring the print image to a print medium, such as the print medium web 17 shown here, and rollers 4, 5 of an inking unit or of a damping unit rest against the plate cylinder 1.
An image-providing unit (not shown here) is likewise arranged on the circumference of the plate cylinder 1, for direct provision of an image.
The erasing and hydrophilizing apparatus has a cleaning apparatus 6 and the drier 7, which can be fed toward the printing plate 2 and moved away from it again. The cleaning apparatus 6 operates by means of a cleaning cloth or cleaning fleece 8, which passes from a feed roller 9 via a pressure roller 10 which presses the fleece 8 against the printing plate 2, and is then wound onto a wind-up roller 11.
The pressure roller 10 is in turn rotatably mounted in a vibrating head 12. The vibrating head 12 is pressed against the printing plate 2 by means of a pressure cylinder 13. Nozzles 14, which are present in front of the cleaning apparatus 6 in the direction of rotation of the plate cylinder 1, can apply a cleaning liquid or a cleaning paste, a hydrophilizing agent, for example a plate cleaner, or another agent which serves either for erasing the printed image applied to the printing plate 2 and for removing printing ink residues or for hydrophilizing the surface of the printing plate 2, to the printing plate. This agent, together with the dirt which it removes, can be taken up by the cleaning cloth 8 if the pressure cylinder 13 presses the pressure roller 10 against the printing plate 2 and the cleaning cloth 8 is moved past the printing plate 2. The nozzles 14 can preferably be adjusted with regard to their angle to spray the agent 215~012 either directly onto the printing plate 2 or onto the cleaning cloth 8. The pressure roller 10 is, for example, rubber-coated. The cleaning cloth 8 is wound either in portions or continuously from the feed roller 9 onto the wind-up roller 11. Preferably, the pressure with which the cleaning cloth 8 is pressed against the printing plate 2 can also be varied.
The printing plate 2 cleaned by the cleaning apparatus 6 can then be dried by the drier 7, with hot air via a hot air supply apparatus 15. The hot air flows subsequently, when it contains, for example, solvent residues, back through an extraction apparatus 16.
The erasing and hydrophilizing apparatus can, for example, be positioned alternately at the plate cylinder 1 or at the rubber blanket cylinder 3 if it is also intended to clean the rubber blanket by means of the erasing and hydrophilizing apparatus.
In another embodiment, the erasing and hydrophilizing apparatus is located outside the printing press, in order there to clean only printing plates 2 or rubber blankets.
The cleaning solutions used are solvents for removing the printing ink residues and the polymer layer applied imagewise, or other cleaning agents which contain abrasive media, such as, for example, some of the plate cleaners conventionally used in the graphics industry, or water for removing abrasive residues. The cleaning agents can be used one after the other in any desired sequence or in a changing sequence. Also, the printing plate surface to be erased can also be rubbed off with a dry cleaning cloth after or between the individual cleaning steps.
In order to increase the efficiency of cleaning agents containing abrasive media, the cleaning cloth 8 preferably moves in a manner which changes.
215~012 The invention provides a printing plate 2 which can be repeatedly directly provided with an image and erased and is suitable for a wet offset printing method. I-t has a smooth and pore-free surface which is hydrophilic or can be hydrophilized after being provided with an image. The printing plate 2 contains no strong microdipoles and consists of a ceramic, a glass or a metal, in particular of a metal alloy. By means of an erasing and hydrophilizing apparatus 6, 7 preferably integrated in the printing press, the printing plate 2 can be repeatedly erased and prepared, i.e. rehydrophilized, for a further image-providing and printing process.
The invention is not limited by the embodiments described above which are presented as examples only but can be modified in various ways within the scope of protection defined by the appended patent claims.
Claims (26)
1. A printing plate which can be directly provided with an image and erased and is suitable for wet offset printing, said printing plate comprising a pore-free and smooth surface with a roughness Ra of <
1 µm, which surface is at least one of hydrophilic and hydrophilizable, the plate also contains no strong microdipoles.
1 µm, which surface is at least one of hydrophilic and hydrophilizable, the plate also contains no strong microdipoles.
2. The printing plate as defined in claim 1, wherein said plate is made of a ceramic having a surface roughness Ra 0.3 µm.
3. The printing plate as defined in claim 2, wherein said plate is a ceramic prepared by one of a sol-gel process, a PVD process, a CVD process and a thermal spray process.
4. The printing plate as defined in claim 2, wherein said plate is a sintered ceramic.
5. The printing plate as defined in claim 2, 3 or 4, wherein said surface is sealed.
6. The printing plate as defined in claim 2, 3 or 4, wherein said plate further includes at least one of alumina, aluminum silicate (mullite), zirconium silicate and zirconium oxide.
7. The printing plate as defined in claim 2, wherein said ceramic plate is hydrophilic throughout its volume.
8. The printing plate as defined in claim 1, 2 or 3, wherein said plate contains at least one phosphate compound.
9. The printing plate as defined in claim 1, wherein said plate is made of a chemical and heat resistant glass material.
10. The printing plate as defined in claim 9, wherein said plate is made of a borosilicate glass.
11. The printing plate as defined in claim 1, wherein said plate is made of a metal and has a surface roughness Ra 0.2 µm.
12. The printing plate as defined in claim 11, wherein said metal is resistant to oxidation.
13. The printing plate as defined in claim 12, wherein said metal is resistant to oxidation during thermal cycling.
14. The printing plate as defined in claim 11, 12 or 13, wherein said metal is an alloy.
15. The printing plate as defined in claim 14, wherein said alloy is a chromium nickel steel.
16. The printing plate as defined in claim 14, wherein said alloy contains nickel, chromium and one of iron and molybdenum.
17. The printing plate as defined in claim 16, wherein the alloy is selected from the group of alloys represented by the material Nos. 2.4665, 2.4851, 2.4819, 2.4602, 2.4636, 2.4638 and 2.4856.
18. A printing press, comprising:
a plate cylinder;
a printing plate mounted on the plate cylinder; and erasing and hydrophilizing means arranged to be operatively positionable at the plate cylinder for cleaning the printing plate and hydrophilizing a surface of the printing plate.
a plate cylinder;
a printing plate mounted on the plate cylinder; and erasing and hydrophilizing means arranged to be operatively positionable at the plate cylinder for cleaning the printing plate and hydrophilizing a surface of the printing plate.
19. The printing press as defined in claim 18, wherein the erasing and hydrophilizing means includes a cleaning apparatus with a cleaning cloth, the cleaning cloth being arranged to be contactable with the printing plate.
20. The printing press as defined in claim 19, wherein said erasing and hydrophilizing means further comprises a dryer operative to fix a print image produced on the printing plate.
21. The printing press as defined in claim 19 or 20, wherein said cleaning apparatus includes nozzles operatively arranged to apply a cleaning agent to the printing plate.
22. The printing press as defined in claim 19 or 20, wherein said cleaning apparatus further includes a pressure roller engageable with the cleaning cloth for pressing the cloth against the printing plate, and a pressure cylinder operatively connected to the pressure roller for pressing the roller against the cleaning cloth.
23. The printing press as defined in claim 22, wherein said cleaning cloth is an elongate strip, the cleaning apparatus further including a feed roller and a wind-up roller, the cleaning cloth having one end attached to the feed roller and another end attached to the wind-up roller, the feed roller and wind-up roller being operative to draw the cleaning cloth from the feed roller over the pressure roller and onto the wind-up roller.
24. The printing press as defined in claim 22, wherein said cleaning apparatus includes a vibrating head mounted between the pressure cylinder and the pressure roller.
25. A process for erasing a print image from a printing plate mounted on a plate cylinder, comprising the steps of:
pressing a cleaning cloth against a surface of the printing plate using a pressure roller while the plate cylinder slowly rotates;
unwinding the cleaning cloth from a feed roller and winding the cleaning cloth onto a wind-up roller one of continuously and step wise; and applying a cleaning solution via nozzles one of directly to the surface of the printing plate and to the cleaning cloth.
pressing a cleaning cloth against a surface of the printing plate using a pressure roller while the plate cylinder slowly rotates;
unwinding the cleaning cloth from a feed roller and winding the cleaning cloth onto a wind-up roller one of continuously and step wise; and applying a cleaning solution via nozzles one of directly to the surface of the printing plate and to the cleaning cloth.
26. The process as defined in claim 25, including positioning an erasing and hydrophilizing apparatus which contains the cleaning cloth, the feed roller, the wind-up roller, the pressure roller and the nozzles one of within the printing press at the plate cylinder and outside the printing press for erasing the print image.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4426012.1 | 1994-07-22 | ||
| DE4426012A DE4426012C2 (en) | 1994-07-22 | 1994-07-22 | Erasable printing form, its use and methods for erasing and regenerating the printing form |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2154012A1 CA2154012A1 (en) | 1996-01-23 |
| CA2154012C true CA2154012C (en) | 1999-11-30 |
Family
ID=6523895
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002154012A Expired - Fee Related CA2154012C (en) | 1994-07-22 | 1995-07-17 | An erasable printing plate and a process and apparatus for erasing and regenerating the printing plate |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0693371B1 (en) |
| JP (1) | JP2792835B2 (en) |
| CA (1) | CA2154012C (en) |
| DE (2) | DE4426012C2 (en) |
Families Citing this family (33)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5839369A (en) * | 1995-10-20 | 1998-11-24 | Eastman Kodak Company | Method of controlled laser imaging of zirconia alloy ceramic lithographic member to provide localized melting in exposed areas |
| US5836249A (en) * | 1995-10-20 | 1998-11-17 | Eastman Kodak Company | Laser ablation imaging of zirconia-alumina composite ceramic printing member |
| US5855173A (en) * | 1995-10-20 | 1999-01-05 | Eastman Kodak Company | Zirconia alloy cylinders and sleeves for imaging and lithographic printing methods |
| US5839370A (en) * | 1995-10-20 | 1998-11-24 | Eastman Kodak Company | Flexible zirconia alloy ceramic lithographic printing tape and method of using same |
| DE19600844A1 (en) * | 1996-01-12 | 1997-07-17 | Heidelberger Druckmasch Ag | Cleaning device for directly produced printing formes |
| DE19600846C1 (en) * | 1996-01-12 | 1997-04-03 | Heidelberger Druckmasch Ag | Cleaning device for laser image printing plate |
| DE19602328A1 (en) | 1996-01-24 | 1997-07-31 | Roland Man Druckmasch | Process for imaging an erasable printing form |
| EP0872339B1 (en) * | 1997-04-18 | 2002-03-06 | Eastman Kodak Company | Zirconia alloy cylinders and sleeves for lithographic imaging and printing methods |
| US5836248A (en) * | 1997-05-01 | 1998-11-17 | Eastman Kodak Company | Zirconia-alumina composite ceramic lithographic printing member |
| US5893328A (en) * | 1997-05-01 | 1999-04-13 | Eastman Kodak Company | Method of controlled laser imaging of zirconia-alumina composite ceramic lithographic printing member to provide localized melting in exposed areas |
| US5925496A (en) * | 1998-01-07 | 1999-07-20 | Eastman Kodak Company | Anodized zirconium metal lithographic printing member and methods of use |
| DE19803787A1 (en) * | 1998-01-30 | 1999-08-05 | Creavis Tech & Innovation Gmbh | Structured surfaces with hydrophobic properties |
| US5927207A (en) * | 1998-04-07 | 1999-07-27 | Eastman Kodak Company | Zirconia ceramic imaging member with hydrophilic surface layer and methods of use |
| DE19826377A1 (en) * | 1998-06-12 | 1999-12-16 | Heidelberger Druckmasch Ag | Printing press and printing process |
| IL124981A0 (en) * | 1998-06-17 | 1999-01-26 | Scitex Corp Ltd | A system and method for offset lithographic printing utilizing a reusable plate |
| DE19939240C2 (en) * | 1999-08-18 | 2002-09-26 | Roland Man Druckmasch | Method and device for reversibly imaging a printing form |
| DE19963124A1 (en) | 1999-12-24 | 2001-07-12 | Roland Man Druckmasch | Cleaning medium and its use |
| DE10008214B4 (en) | 2000-02-23 | 2006-10-12 | Man Roland Druckmaschinen Ag | Extinguishing and cleaning device for cylindrical surfaces, in particular printing plate and blanket cylinders of a printing press |
| DE10008213B4 (en) | 2000-02-23 | 2005-12-08 | Man Roland Druckmaschinen Ag | Device for thermal energy coupling |
| DE10054284B4 (en) | 2000-11-02 | 2010-04-08 | Manroland Ag | Process for the treatment of an erasable lithographic printing plate |
| DE10136068A1 (en) | 2001-07-25 | 2003-02-13 | Heidelberger Druckmasch Ag | Method and device for structuring a surface into hydrophilic and hydrophobic areas |
| US6969541B2 (en) | 2001-07-25 | 2005-11-29 | Heidelberger Druckmaschinen Ag | Method and device for structuring a surface to form hydrophilic and hydrophobic regions |
| DE10154430B4 (en) | 2001-11-06 | 2009-04-02 | Manroland Ag | Method and device for erasing a printed image on a printing form for a printing press |
| DE10206937A1 (en) | 2002-02-19 | 2003-09-04 | Oce Printing Systems Gmbh | Method and device for printing, a wetting-promoting substance having a molecular layer thickness being applied before the application of a dampening solution |
| EP1380417B1 (en) * | 2002-07-03 | 2006-08-23 | Agfa-Gevaert | Positive-working lithographic printing plate precursor |
| DE102004041752A1 (en) * | 2004-08-28 | 2006-03-23 | Man Roland Druckmaschinen Ag | Method and device for de-printing a printing form |
| DE102006049149A1 (en) * | 2006-10-18 | 2008-04-24 | Man Roland Druckmaschinen Ag | Rewritable printing form's surface erasing method for printing machine i.e. digital printing machine, involves executing main erasing step during running out of form cylinder after completion of printing order |
| DE102007057798B4 (en) | 2006-12-20 | 2018-12-06 | Heidelberger Druckmaschinen Ag | Process for treating a printing surface |
| DE102008031140A1 (en) | 2007-07-19 | 2009-01-22 | Heidelberger Druckmaschinen Ag | Apparatus and method for treating a rotating printing surface with a process fluid |
| CN101628514B (en) * | 2008-07-16 | 2012-05-30 | 海德堡印刷机械股份公司 | Method for treating a reusable printing technology surface with at least one liquid |
| DE102008045400A1 (en) * | 2008-09-02 | 2010-03-04 | Fischer & Krecke Gmbh | Process for recycling the surface of a cylinder in a rotary printing machine |
| DE102011106799A1 (en) | 2010-08-04 | 2012-02-09 | Heidelberger Druckmaschinen Aktiengesellschaft | Process for re-imaging a printed printing form |
| US9492996B2 (en) | 2012-12-31 | 2016-11-15 | Goss International Americas, Inc. | Web control to reduce waste and method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS56150592A (en) * | 1980-04-24 | 1981-11-21 | Toyo Ink Mfg Co Ltd | Machine plate for use in lithographic printing |
| JPS5764597A (en) * | 1980-10-09 | 1982-04-19 | Toyo Kohan Co Ltd | Manufacture of metal sheet for plate material |
| DE3248178C2 (en) * | 1982-12-27 | 1987-02-19 | Forschungsgesellschaft Druckmaschinen E.V., 6000 Frankfurt | Image-based coating of printing plates for planographic printing |
| DE3633758A1 (en) * | 1986-10-03 | 1988-04-07 | Man Technologie Gmbh | PRINTING MACHINE |
| JPH02229092A (en) * | 1989-03-01 | 1990-09-11 | Konica Corp | Photosensitive lithographic printing plate |
| DE4123959C1 (en) * | 1991-07-19 | 1993-02-04 | Man Roland Druckmaschinen Ag, 6050 Offenbach, De | |
| DE4216636C2 (en) * | 1992-05-20 | 1995-11-23 | Roland Man Druckmasch | Process and device for erasing and hydrophilizing a printing form imaged by means of a thermal transfer process |
| DE4235242C1 (en) * | 1992-10-20 | 1993-11-11 | Roland Man Druckmasch | Erasable print form |
-
1994
- 1994-07-22 DE DE4426012A patent/DE4426012C2/en not_active Expired - Fee Related
-
1995
- 1995-07-15 EP EP95111169A patent/EP0693371B1/en not_active Expired - Lifetime
- 1995-07-15 DE DE59503418T patent/DE59503418D1/en not_active Expired - Lifetime
- 1995-07-17 CA CA002154012A patent/CA2154012C/en not_active Expired - Fee Related
- 1995-07-21 JP JP7185954A patent/JP2792835B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0852949A (en) | 1996-02-27 |
| JP2792835B2 (en) | 1998-09-03 |
| EP0693371B1 (en) | 1998-09-02 |
| EP0693371A1 (en) | 1996-01-24 |
| DE59503418D1 (en) | 1998-10-08 |
| CA2154012A1 (en) | 1996-01-23 |
| DE4426012A1 (en) | 1996-01-25 |
| DE4426012C2 (en) | 1998-05-20 |
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| Date | Code | Title | Description |
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| EEER | Examination request | ||
| MKLA | Lapsed |