Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41F—PRINTING MACHINES OR PRESSES
  • B41F27/00—Devices for attaching printing elements or formes to supports
  • B41F27/12—Devices for attaching printing elements or formes to supports for attaching flexible printing formes
  • B41F27/1262—Devices for attaching printing elements or formes to supports for attaching flexible printing formes without tensioning means
  • B41F27/1275—Devices for attaching printing elements or formes to supports for attaching flexible printing formes without tensioning means by means of adhesives, staples
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41D—APPARATUS FOR THE MECHANICAL REPRODUCTION OF PRINTING SURFACES FOR STEREOTYPE PRINTING; SHAPING ELASTIC OR DEFORMABLE MATERIAL TO FORM PRINTING SURFACES
  • B41D5/00—Working, treating, or handling stereotype plates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41F—PRINTING MACHINES OR PRESSES
  • B41F27/00—Devices for attaching printing elements or formes to supports
  • B41F27/12—Devices for attaching printing elements or formes to supports for attaching flexible printing formes
  • B41F27/1293—Devices for filling up the cylinder gap; Devices for removing the filler
• • 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
  • B41N6/00—Mounting boards; Sleeves Make-ready devices, e.g. underlays, overlays; Attaching by chemical means, e.g. vulcanising
  • B41N6/02—Chemical means for fastening printing formes on mounting boards
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C1/00—Forme preparation
  • B41C1/02—Engraving; Heads therefor
  • B41C1/04—Engraving; Heads therefor using heads controlled by an electric information signal
  • B41C1/05—Heat-generating engraving heads, e.g. laser beam, electron beam
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T156/00—Adhesive bonding and miscellaneous chemical manufacture
  • Y10T156/10—Methods of surface bonding and/or assembly therefor
  • Y10T156/1052—Methods of surface bonding and/or assembly therefor with cutting, punching, tearing or severing
  • Y10T156/1062—Prior to assembly
  • Y10T156/1066—Cutting to shape joining edge surfaces only

Definitions

• a disadvantage of the known method is that the resulting gap closure compound is very firmly bonded to the material of the flexographic printing plate, so that it is not possible to separate the edges and remove the gap closure compound without damaging the printing plates.
• the gap sealing compound as such has a very high elongation at break, so that after it has been produced it can only be smoothed by machine grinding, its thickness adapted to the printing forms and / or removed from the surface of the printing forms running along the connected edges, which can be removed by
• a very particular disadvantage is when the edge connections cut through solid printing areas of the printing forms. Because mechanical sanding creates grinding marks in the surface of the printing forms, which have a different surface roughness and different ink transfer properties than the non-sanded areas and which are therefore already visible in the printed product at the start of the printing process. Because of its high elongation at break, the gap sealing compound can only be cut up, after which the remnants adhere very firmly to the printing form material. Or it can only be torn apart with great force, whereby the Printing forms are permanently damaged and are no longer reusable.
• the flexing processes during printing can lead to a deformation of the precisely fitting edges of the carrier foils, which may be severely damaged under certain circumstances, on these flexographic printing plates which are fixed and connected to the edges on printing cylinders.
• the object of the invention was to improve the known method for connecting the cut edges of photopolymerized flexographic printing plates, which have relief layers and dimensionally stable carrier films, on a printing cylinder in such a way that the disadvantages described above no longer occur.
• all photopolymerizable mixtures are suitable for filling the gap between the edges to be joined in process step (a), provided that they are liquid and can be photopolymerized by UV radiation to give rubber-elastic gap sealing compounds.
• the suitable mixtures contain binders, photopolymerizable monomers compatible with them and initiators of photopolymerization.
• they can contain customary and known inhibitors of thermally initiated polymerization, antioxidants, antiozonants, plasticizers, fluxes, tackifiers, solvents and / or fillers.
• photopolymerizable mixtures which are particularly suitable according to the invention are the solvent-free mixtures known from GB-A-2 160 882.
• flexographic printing plates can be used as photopolymerized flexographic printing plates in the process according to the invention, which have relief layers and dimensionally stable carrier foils or consist of these and which are known to be obtained by imagewise exposure of printing plates which can be crosslinked by photopolymerization and washing out the unexposed and therefore uncrosslinked areas.
• Printing plates suitable for this usually contain a photopolymerizable, relief-forming layer on a dimensionally stable carrier film.
• the flexographic printing forms obtainable in this way have relief layer thicknesses of 0.7 to 10 mm, preferably 3 to 7 mm and a relief depth of 0.5 to 5 mm.
• the width of the gap between the edges to be joined should generally not exceed 2 mm and not less than 0.1 mm. Gap widths between 0.5 and 1.5 mm are advantageous according to the invention.
• the printing cylinders customary and known in flexographic printing are used.
• the commercially available UV light sources such as the superactinic fluorescent tubes are suitable for exposing the photopolymerizable mixtures in process step (b).
• Plates or foils made of suitable plastics such as polycarbonate, polypropylene, polyethylene or polyethylene terephthalate, which are pressed onto the gap filled with a photopolymerizable mixture, can be used as firmly attached, translucent covers.
• the plates have approximately the same curvature as the surface of the impression cylinder.
• the additional use of shrink films or plastic stockings is an advantage when connecting edges on a pressure cylinder.
• the printing forms are fixed on dressing cylinders with the aid of customary and known adhesive films 1 before the liquid photopolymerizable mixture is filled in (method step (a)).
• the adhesive films 1 have the same area as the printing forms.
• the dressing cylinders or assembly cylinders to be used in the method according to the invention are part of a known, commercially available one Assembly equipment for the preparation of flexographic printing plates for multi-color printing.
• the printing forms fixed on the dressing cylinders are cut to fit the printing cylinders, after which they are detached from the dressing cylinders and from the adhesive films 1. Thereafter, the precisely tailored printing forms are fixed on the printing cylinders by means of customary and known double-sided adhesive films 2.
• the adhesive films 2 to be used in the method according to the invention are of the same area as the printing forms. However, they have 1.6 to 2.6 times, in particular 1.8 to 2.2 times, the thickness of the adhesive film 1.
• dressing cylinders in the method according to the invention which have at least one notch running parallel to the axis and at least one notch running in the perpendicular direction.
• the printing forms are fixed on these dressing cylinders in such a way that the notches come to rest under the interfaces.
• edges of the printing forms and the adhesive films are then cut exactly along these notches, the cutting devices used for this being guided in these notches.
• the usual and known cutting devices can be used here. It is particularly advantageous, however, to use 100 to 150 ° C., in particular 110 ° C. to 130 ° C., hot knives with a trapezoidal cutting edge in the method according to the invention, which can be moved parallel to the axis of the dressing cylinder and at an angle of 0 ° and 90 ° the cylinder axes are fixable.
• the usual and well-known carpet cutters come into consideration as knives with a trapezoidal cutting edge. These can be heated using soldering irons to which they are attached.
• the knee joints themselves can be fixed in two positions so that the knives are at an angle of 0 ° or 90 ° to the cylinder axes.
• the dressing cylinders are fixed in the desired positions with the printing forms lying on them, and the knives are moved.
• the knives are fixed in the desired position and the dressing cylinder is rotated.
• the photopolymerizable mixture serving as the subsequent gap sealing compound is not completely polymerized in process step (b), but only partially.
• the degree of photopolymerization or crosslinking may neither be chosen too high nor too low, because otherwise the particular advantages of the process according to the invention are lost.
• the photopolymerizable mixture may therefore only be partially polymerized out until the conditions for the elongation at break in the combination of solid gap sealing compound and printing form material are the condition R S ⁇ R S / F «R F is fulfilled.
• R S means the elongation at break of the solid gap closure compound. Depending on the photopolymerizable mixture used, it is 2 to 3 kp / 2 cm.
• R S / F denotes the corresponding elongation at break in the interface between the gap sealing compound and the printing form material. Depending on the materials used, it is 1 to 2 kp / 2 cm.
• R F denotes the elongation at break of the flexographic printing material. Depending on the material used, it is 6 kp / 2 cm or above 6 kp / 2 cm.
• the elongation at break values can be easily determined using an Instron on 2 cm wide samples at a pull-off angle of 90 °.
• the degree of photopolymerization or photocrosslinking can be set very easily via the exposure time. With given mixtures and flexographic printing plates, the optimal degree of polymerization or crosslinking, at which the condition according to the invention is fulfilled, can easily be determined on the basis of simple preliminary tests.
• the liquid photopolymerizable mixture can be filled into the gap between two edges to be connected, for example by means of a high-pressure injection gun or by means of a cartridge with a curved outlet nozzle, from which the mixture is pressed out using a screw thread. If a high-pressure injection gun is used here, it is advantageous to cover the gap; when using a cartridge with an outlet nozzle, this is generally passed through the uncovered gap.
• the gap fillings are advantageously covered with polyethylene terephthalate films, after which the printing cylinders together with the printing plates and polyethylene terephthalate films lying on them are bandaged in the usual manner with the known plastic stockings.
• the polyethylene terephthalate films are pressed firmly onto the gap fillings, as a result of which some of these gap fillings can, under certain circumstances, be pressed again onto the surface of the printing forms that runs along the edges to be joined.
• the solid gap sealing compounds After exposure of the gap fillings from the liquid photopolymerizable mixture in the procedure according to the invention, the solid gap sealing compounds are obtained, the elongation at break of which fulfills the critical condition as claimed.
• These gap sealing compounds can be slightly curved. They can also have an uneven surface. They can also be thicker than the edge areas of the printing forms.
• parts of the gap closure compound can along the connected Edges of the printing form are located. It may therefore be necessary to smooth these gap sealing compounds and / or to adapt their thickness to the printing forms and / or to remove the parts of the gap sealing compound which are located on the surface of the printing forms running along the connected edges.
• the generally known mechanical methods such as grinding, cutting or sandblasting can be used for this.
• the method according to the invention for connecting the cut edges of photopolymerized flexographic printing plates, which have relief layers and dimensionally stable carrier films, on a printing cylinder has particularly unexpected technical effects.
• gaps are produced between the edges of printing forms to be connected, which are guided so narrowly and precisely that they do not make themselves noticeably noticeable even if they cut through printing solid areas of the printing forms.
• edges of the dimensionally stable carrier foils of the printing forms no longer abut one another in the gaps and can therefore no longer cause any disadvantageous effects.
• the partially polymerized gap closure compounds located in these columns and produced in the procedure according to the invention are easy to smooth and / or their thickness can be adapted to the printing forms.
• parts of the gap sealing compounds can be removed from the surface of the printing plates running along the connected edges in a simple manner, without the surface being damaged or their surface roughness and their ink transfer properties being adversely changed.
• the gap sealing compounds connect the edges seamlessly and are permanently sealed under printing conditions and resistant to the printing ink solvents. They are also not deformed or damaged by the flexing forces that occur during printing, so that - even after very long print runs - the masses are not raised or even detached. The columns are therefore hardly visible in the printed image.
• the gap sealing compounds allow problem-free, clean re-opening of the Edges if the flexographic printing plate is to be removed from the printing cylinders and stored separately. The separation takes place above all at the interface between gap sealing compound and flexographic printing material; however, it can also occur to a minor extent in the gap closure material itself.
• the remainder of the gap closure material which may still adhere to the edges, can be rubbed off or scraped off without any problem, without the printing plates being damaged.
• the flexographic printing plates can be fixed again on the printing cylinders for reuse, after which their edges can be connected anew in the manner according to the invention. The method thus enables a somewhat reversible edge connection.
• the flexographic printing forms connected to the edges by the process according to the invention have better printing behavior than those which have been connected by conventional processes.
• ®Nyloflex FA flexographic printing plate from BASF Aktiengesellschaft with the dimensions 40 cm ⁇ 61 cm ⁇ 2.84 mm
• the photopolymerized flexographic printing plate obtained in the known manner and having a thickness of 2.84 mm and a relief depth of 1.2 mm was cut to the dimensions 40 cm ⁇ 60 cm using a 0.1 mm thick, 40 cm ⁇ 61 cm , double-sided adhesive film 1 on the dressing cylinder of a commercially available assembly device (Bieffebi assembly device) so fixed that an axially parallel notch milled into the dressing cylinder came to lie exactly below the later interface in the flexographic printing plate. This interface was located in a solid printing area of the printing form.
• the knife with which the cut was made consisted of the trapezoidal cutting edge of a commercially available carpet cutter, which was clamped in a soldering iron. This in turn was connected via a knee joint to a linkage attached below the front of the dressing cylinder and running axially parallel to it.
• the knife edge was heated to 110 ° C by bending the knee joint into the notch of the Dressing cylinder inserted and fixed at an angle of 0 ° to the cylinder axis. After that, the dressing cylinder was locked.
• the entire arrangement of knife, soldering iron and knee joint was then shifted along the rod parallel to the axis, the flexographic printing plate and the adhesive film 1 being cut very cleanly at the desired location.
• the cut flexographic printing plate was then detached from the adhesive sheet 1 and applied to a printing cylinder (circumference: 40 cm) using a 0.2 mm thick, double-sided adhesive sheet 2 measuring 40 cm ⁇ 60 cm so that the 60 cm long side of the printing plate came to lie parallel to the cylinder axis.
• a gap of 1.2 mm between the longitudinal edges of the printing form on the printing cylinder which gap had to be filled with gap sealing compound.
• the surface of the flexographic printing plate was covered with adhesive strips along the edges to be joined.
• This mixture was poured into a cartridge and pressed into the gap via a screw thread through a 0.8 mm wide, slightly curved outlet nozzle, the outlet nozzle being guided along the gap. This resulted in a filling with a slight curvature, which protruded above the level of the printing form surface. In part, the filling overflowed onto the surface of the flexographic printing plate covered with adhesive strips. These parts were removed from the flexographic printing plate surface together with the adhesive strips.
• the gap filling was then covered with a polyethylene terephthalate film and the entire flexographic printing cylinder was wrapped with a polyethylene stocking running along the cylinder axis.
• the mixture was then exposed in the gap in a tube exposer for 15 minutes. After this exposure time, which had been determined on the basis of preliminary tests, the mixture was polymerized to such an extent that the elongation at break R S (1.5 kg / 2 cm) and the elongation at break RS / F (2 kg / 2 cm) together with the elongation at break R F (6.5 kp / 2 cm) met the condition according to the invention.
• the elongations at break were measured in a known manner using an Instron on 2 cm wide samples at a take-off angle of 90 °.
• the gap sealing compound was smoothed by rubbing with a soft leather cloth or a plastic scraper, the thickness of the flexographic printing plate was adapted and removed from the surface of the flexographic printing plate running along the connected edges. Neither the printing form nor the gap sealing compound was damaged in any way.
• Plastic sheets were printed with the usual alcohol-soluble flexographic printing ink using the finished flexographic printing cylinder in a conventional flexographic printing unit. Even after a run of 4.104 copies, the image reproduction was of excellent quality. The gap closure was hardly visible in the printed image. At the end of the printing process, the gap sealing compound showed no deformation, cracks or detachments. However, the gap sealing compound could very easily be removed from the gap by hand or with the aid of a plastic spatula, without the flexographic printing plate being damaged.
• the flexographic printing plate was detached from the printing cylinder and stored separately. For reuse, it was fixed again with an adhesive film 2 on the printing cylinder and the gap between its edges was closed again in the manner described above.
• the portions of the gap sealing compound that exceeded the level of the flexographic printing plate had to be cut away with a sharp knife because of their high toughness and strength. After this, the gap sealing compound had to be smoothed with a grinder. Both the grinding and the cutting were difficult to carry out because of the high rubber elasticity of the mass; Damage to the flexographic printing form could not be avoided.
• the gap sealing compound could only be cut with a sharp knife. Remains of the gap sealing compound remained firmly attached to the printing form material. When trying to cut, tear off or grind away these adherent parts, the edge areas of the flexographic printing plate were severely damaged. The flexographic printing plate was therefore no longer suitable for reuse.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Photosensitive Polymer And Photoresist Processing (AREA)
• Printing Plates And Materials Therefor (AREA)
• Manufacture Or Reproduction Of Printing Formes (AREA)
• Turning (AREA)
• Joining Of Corner Units Of Frames Or Wings (AREA)
• Table Equipment (AREA)
• Manufacture Of Macromolecular Shaped Articles (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (3)

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ID=6325271

Family Applications (1)

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Cited By (3)

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• 1987
  • 1987-04-09 DE DE19873712070 patent/DE3712070A1/de not_active Withdrawn
• 1988
  • 1988-03-31 EP EP88105252A patent/EP0286020B1/fr not_active Expired - Lifetime
  • 1988-03-31 ES ES88105252T patent/ES2023457B3/es not_active Expired - Lifetime
  • 1988-03-31 DE DE8888105252T patent/DE3863955D1/de not_active Expired - Lifetime
  • 1988-03-31 AT AT88105252T patent/ATE65743T1/de not_active IP Right Cessation
  • 1988-04-07 US US07/178,904 patent/US4828641A/en not_active Expired - Fee Related
  • 1988-04-08 JP JP63085547A patent/JPS63261364A/ja active Pending

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