Classifications

• • 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

Definitions

• the invention relates to a method for fixing a multilayer relief printing plate for flexographic printing on a printing cylinder.
• the assembly of relief printing forms using such double-sided adhesive films is generally carried out in such a way that first the adhesive film is glued on one side to the metal cylinder and then the flexographic printing plate is placed and fixed precisely by hand on the free adhesive surface, which can be quite time-consuming.
• the relief printing plate is removed from the cylinder and stored so that it can be reused if necessary and in turn applied to a metal cylinder provided with double-sided adhesive film.
• the aim of the present invention was to avoid the disadvantages described above and to show a method for fixing multilayer relief printing plates on printing cylinders, which makes the previously usual work with double-sided adhesive film mounted on the cylinder superfluous and enables tolerance-accurate printing with tolerances ⁇ 10 ⁇ m.
• the printing form should be removed properly without damaging it and without destroying the adhesive layer / printing form composite, and the printing form should be detached without residue without the printing cylinder becoming dirty.
• this goal could be achieved by applying a pressure-sensitive adhesive layer with an adhesive strength of 1 to 6 N / 25 mm to the lower layer of the multilayer relief printing plate.
• the present invention relates to a method for fixing a multilayer relief printing plate for flexographic printing on a printing cylinder, the relief printing plate comprising a lower layer (U) made of an elastomeric material, a relief layer (P) consisting of a mixture which has been photo-crosslinked by irradiation with actinic light the photocrosslinking has contained a mixture of 50 to 99% by weight of an elastomer and 1 to 50% by weight of at least one photopolymerizable olefinically unsaturated monomer which is largely compatible with the elastomer, and one between the lower layer (U) and the relief layer (P) in each case by means of thin adhesive layers attached intermediate layer (Z), which is insoluble in the developer solvent used in the relief production and in the printing ink solvents and does not let them through, is composed, which is characterized in that the side of the lower layer (U) facing away from the intermediate layer (Z) also one for act is light-permeable pressure-sensitive adhesive layer is provided, which is
• a preferred mode of operation of the method according to the invention is to use a double-sided adhesive film as the pressure-sensitive adhesive layer, which has a higher adhesive strength on the side glued to the lower layer (U) than on the side facing the printing cylinder.
• the pressure-sensitive adhesive layer has a thickness between 5 and 100, in particular between 10 and 50 ⁇ m.
• Multi-layer printing plates and multi-layer relief printing forms for flexographic printing are described for example in DE-A 23 00 371, in DE-A 23 01 175, in US-A 3 556 791 and in DE-A 24 44 118.
• Suitable elastomeric materials for the underlayer (U) are, for example, natural rubber, polybutadienes, butadiene-acrylonitrile copolymers, butadiene-styrene copolymers, silicone rubber, polysulfide rubber, vinylidene chloride-hexafluoropropylene copolymers, isoprene-styrene and butadiene-styrene block copolymers especially polyurethane elastomers, which can be obtained in a known manner from higher molecular weight polyhydroxyl compounds, such as polyesters or polyethers, optionally low molecular weight polyols, and also polyisocyanates, in particular diisocyanates.
• the materials for the layer (U) should expediently be processable into low-tolerance layers, for example by Casting and hardening in molds or heatable centrifuges or in the case of thermoplastic materials, for example by calendering. It is also possible to produce the layer (U) from foam-like materials or to use foams therefor, provided that these have the appropriate elasticity and do not exert a sponge effect (absorbent effect) on the printing ink or developer solvents.
• the materials of layer (U) are preferably not or only sparingly soluble in the developer solvents for the relief layer.
• Layer thicknesses of 0.5 to 6 mm can generally be chosen for the lower layer (U). Materials which have an elastic modulus of 1 to 20 N / mm2 are preferred for this.
• Plastic layers, metal foils or crosslinked lacquer layers are suitable as an intermediate layer or barrier layer (Z), which can also be covered by fabric, e.g. Textile fabric or glass fiber fabric, can be reinforced.
• Intermediate layers (Z) can thus be obtained by impregnating glass fiber fabrics with crosslinkable polymers or monomers or mixtures thereof, e.g. by impregnating with unsaturated polyester resins and crosslinking them after or under molding.
• the intermediate layers (Z) can for example have a thickness of about 5 to 500 microns and in particular 10 to 200 microns and an elastic modulus of 1 ⁇ 102 to 2.1 ⁇ 105 N / mm2.
• the intermediate layers (Z) should not be soluble in the solvent or solvents used for the development of the relief after exposure and in the organic solvents usually contained in printing inks, and should swell as little as possible in them, and the lowest possible permeability for these dyes and Have developer solvents.
• Typical solvents of this type are alcohols, such as ethanol or isopropanol, esters, such as ethyl acetate, hydrocarbons and ketones, such as acetone or methyl ethyl ketone.
• Polymer films and in particular films made of polyester, such as polyethylene terephthalate films, especially biaxially stretched polyethylene terephthalate films, are preferably used for the intermediate layer (Z).
• Such intermediate layers (Z) are preferred which are transparent to visible light, in order to mount the plates on the To facilitate plate cylinders, and in particular those that are also permeable to the actinic light effective for the photocrosslinkable layer or the photoinitiator therein (in general for light down to a wavelength of about 320 ⁇ m) and thus make it possible, for example a Perform pre-exposure of the photocrosslinkable layer from the back of the plate.
• the elastomer-monomer mixtures known per se for photopolymer printing plates for flexographic printing can be used insofar as they are no longer soluble in the developer solvent after full tone exposure in the photocrosslinkable state .
• the photocrosslinked layer (P) (relief layer P) preferably has an equal or preferably higher elastic modulus than the lower layer (U).
• the modulus of elasticity of the relief layer (P) i.e. the photocrosslinked layer (P)
• elastomer materials mentioned above for layer (U) and mixtures thereof are suitable as elastomers for the photocrosslinkable layer, provided that they are soluble in the developer solvent.
• Very suitable are elastomeric butadiene or isoprene block copolymers and elastomeric polyether and polyester urethanes and of these particularly polyurethane elastomers, which are reacted by reacting an aliphatic saturated polyester glycol with a molecular weight of 400 to 4000 with an organic diisocyanate and optionally an aliphatic diol with 2 to 10 carbon atoms were produced as chain extenders.
• the monomers for the photocrosslinkable layer should be largely compatible with the related polymer material, ie they should not separate even when the mixture or the layer has been stored for a long time and should be readily photopolymerizable by irradiation with actinic light in the presence of a photoinitiator.
• Examples of very suitable monomers are the acrylates and especially the diacrylates and polyacrylates and the corresponding methacrylates of aliphatic or cycloaliphatic diols and polyols with generally 2 to 20 carbon atoms, for example butanediol-1,4-diacrylate, the reaction products made from polyisocyanates and which are practically free from isocyanate groups in particular aliphatic diisocyanates with 6 to 36 carbon atoms and (meth) acrylic esters which have a hydroxyl group in the alcohol radical, such as butanediol-1,4-monoacrylate, and also N-vinyl compounds, in particular N-vinylpyrrolidone.
• the photocrosslinkable layer usually also contains a photoinitiator, generally in an amount of 0.01 to 10 and in particular 0.01 to 5% by weight, such as benzoin or benzoin derivatives, e.g. Benzoin methyl or isopropyl ether, ketals such as e.g. Benzyl dimethyl ketal and acylphosphine oxide, diacylphosphine oxide or acylphosphine sulfide compounds.
• a photoinitiator generally in an amount of 0.01 to 10 and in particular 0.01 to 5% by weight, such as benzoin or benzoin derivatives, e.g. Benzoin methyl or isopropyl ether, ketals such as e.g. Benzyl dimethyl ketal and acylphosphine oxide, diacylphosphine oxide or acylphosphine sulfide compounds.
• the photocrosslinkable layer can also contain other conventional additives, such as thermal polymerization inhibitors, such as p-methoxyphenol, hydroquinone or salts of N-nitrosocyclohexylhydroxylamine, dyes or plasticizers (to improve the processability of the mixture of the layer).
• thermal polymerization inhibitors such as p-methoxyphenol, hydroquinone or salts of N-nitrosocyclohexylhydroxylamine, dyes or plasticizers (to improve the processability of the mixture of the layer).
• the multilayer printing plates it is often advantageous for the multilayer printing plates to also apply a bonded, thin, adhesive-free coating layer to the photocrosslinkable layer, which is made from a hard, non-sticky, transparent and tear-resistant film-forming polymer, e.g. a polyamide or copolyamide soluble in the developer solvent or from a mixture of such a polymer with a small amount ( ⁇ 10% by weight) of a photopolymerizable monomer and photoinitiator and optionally inhibitor.
• a hard, non-sticky, transparent and tear-resistant film-forming polymer e.g. a polyamide or copolyamide soluble in the developer solvent or from a mixture of such a polymer with a small amount ( ⁇ 10% by weight) of a photopolymerizable monomer and photoinitiator and optionally inhibitor.
• This coating layer enables a tack-free, bubble-free negative overlay in relief printing plate production from the multi-layer printing plates, which in some cases is not possible without the photo-crosslinkable layer because of the surface tackiness of the plates.
• the coating layer is washed away together with the uncrosslinked layer portions.
• cover layer with a removable protective layer such as a polyester film, which can also be applied to the photocrosslinkable layer together with the cover layer.
• This protective layer is generally stripped off prior to imagewise exposure of the photocrosslinkable layer, while the coating layer generally remains on the photocrosslinkable layer.
• the elastomeric lower layer (U) on the side facing away from the intermediate layer (Z) has a 0.1 to 20 and in particular 0.2 to 10 ⁇ m thick coating layer based on a tack-free polymer.
• the same polymers are often suitable for this as can be used for the production of the coating layer.
• the coating layer should also preferably be permeable to actinic light.
• the layers (U), (Z) and (P) are bonded together.
• the adhesive connection between the respective layers is produced by applying thin layers of adhesion promoters or adhesives on one or both sides and firmly gluing the layers, which then results in thin adhesive layers between layers (U) and (Z) and between layers (Z) and (P) arise, which are however less than 100 microns and preferably less than 30 microns thick.
• Commercial one- and two-component adhesives can be used for the adhesive layers, the type of which depends on the type of materials or polymer types used for layers (U) and (Z) and (Z) and (P).
• the commercially available reaction adhesives based on polyurethane and polychloroprene which can be applied to the layers to be joined by subtraction or casting in a suitable layer thickness, may be mentioned as frequently suitable adhesives.
• Relief printing forms have proven to be particularly suitable in which the lower layer (U) is 1000 to 5000 ⁇ m thick and has a modulus of elasticity of 1.5 to 10 N / mm2, the intermediate layer has a thickness of 20 to 125 ⁇ m and an elastic modulus of 2, 5 ⁇ 103 to 104 N / mm2 and the photocrosslinked relief layer (P) has a thickness of 400 to 1000 ⁇ m and an elastic modulus of 3 to 50 N / mm2.
• the side of the lower layer (U) facing away from the intermediate layer (Z) is provided with a pressure-sensitive adhesive layer which is firmly bonded to the lower layer (U) on one side and an adhesive force of 1 to 6 N / 25 mm on the other side having.
• This pressure-sensitive adhesive layer generally has a thickness between 5 and 100, preferably between 10 and 50 ⁇ m.
• Suitable pressure sensitive adhesives are, in particular, so-called peelable pressure sensitive adhesives, for example those based on polyisobutylene, polyacrylate, polyacrylate dispersions, rubbers and others.
• Such pressure-sensitive adhesives can be applied, for example, by direct application of a uniform layer of the above-mentioned thickness to the lower layer (U) of the printing form or the underlying printing plate which is still to be exposed, in which case the pressure-sensitive adhesive layer is expediently covered with a protective film which is permeable to actinic light and Washing out and post-treatment after the imagewise exposure of the printing plate either use solvents which do not impair the pressure-sensitive adhesive layer or appropriate precautions are to be taken to prevent these solvents from penetrating into the pressure-sensitive adhesive layer.
• a further advantageous possibility of applying a pressure-sensitive adhesive layer with an adhesive strength of between 1 and 6 N / 25 mm on the lower layer (U) of the multilayer relief printing plate is to fix a double-sided adhesive film with the one adhesive layer on the lower layer (U), the latter Adhesive layer generally has a higher adhesive strength than the pressure-sensitive adhesive layer on the other side of the adhesive film, which has an adhesive strength between 1 and 6 N / 25 mm and is used to fix the relief printing form on the printing cylinder.
• the side of the adhesive layer of the double-sided adhesive tape to be glued to the underlayer (U) can be made from adhesives of the above-mentioned type as well as from other adhesives such as e.g. There are two-component adhesives, radiation-curing adhesives, curable polyurethane adhesives and cellulose ester adhesives that form a firm bond with the lower layer (U).
• the pressure-sensitive adhesive layer For the storage of the printing plate or printing form provided with the pressure-sensitive adhesive layer, it can be advantageous to cover the pressure-sensitive adhesive layer with a protective film or with siliconized paper.
• the parts and percentages given in the examples below relate to the weight.
• the modulus of elasticity is determined according to DIN 53 457, the adhesive strength according to AFERA test standard No. 4001 (peel strength) of the Association of Adhesive Film Manufacturers.
• a multilayer printing plate made up of a 2 mm thick lower layer (U) of a polyurethane elastomer made of polyester and 2,4-tolylene diisocyanate with a modulus of elasticity of 2.5 N / mm2, one with a commercially available polyurethane adhesive with the lower layer (U) on the one hand and the photocrosslinkable layer, on the other hand, glued biaxially stretched polyethylene terephthalate film of 75 ⁇ m thickness and a modulus of elasticity of 4.5 ⁇ 103 N / mm2 as intermediate layer (Z) and a 0.7 mm thick photocrosslinkable layer, consisting of a mixture of 80 parts of a commercially available thermoplastic Processable isocyanate group-free polyurethane elastomers (reaction product adipic acid-ethylene glycol-polyester / diphenylmethane diisocyanate / ethylene glycol), 10 parts of butanediol-1,4-diacrylate and 10 parts of
• the relief printing plate with the layers (P), (Z) and (U) thus produced is applied to the side of the lower layer (U) facing away from the intermediate layer (Z) one side (adhesive force 7 N / 25 mm) of a double-sided adhesive film with a total thickness of 25 ⁇ m and pressed firmly.
• the printing form with the relief layer (P) is laid down, the protective film (siliconized paper) is peeled off from the adhesive layer, which has an adhesive force of 1.5 N / 25 mm, and the printing form is used using a method customary in the graphic arts industry Assembly device mounted precisely on a printing cylinder. Repeated pulling off and putting on the relief printing form from or onto the printing cylinder is easy and problem-free.
• the relief printing form After the print run (over 1.2 million copies) in the printing press, the relief printing form is released from the printing cylinder for the purpose of storage and reuse. It is easy to pull off the impression cylinder, which prevents damage or destruction of the relief printing plate due to kinks or overextension.
• the adhesive layer of the printing form can be covered with siliconized paper or a protective film for storage. Even in the second, third and fourth assembly and printing processes, the adhesive force of the lower layer of the multilayer relief printing form is sufficient to ensure perfect printing conditions and problem-free detachment and reuse of the printing form.
• a multilayer printing plate of the structure described in Example 1 is provided with a 10 ⁇ m thick adhesive layer on the side of the lower layer (U) facing away from the intermediate layer (Z).
• This adhesive layer has an adhesive strength of 4 N / 25 mm and is covered with a protective film which is permeable to actinic light.
• the protective film is removed from the adhesive layer of the printing plate and, as described in Example 1, the latter is fixed on the printing cylinder. In this case, too, assembly and disassembly takes place without damaging the printing form.
• the printing form behaves perfectly in the printing press, without a detachment of the printing form from the printing cylinder being observed during printing (print run> 800,000 prints).
• the adhesive layer was covered again with protective film or protective paper and stored for 4 months. Reuse for printing was also easy after this time.
• Example 1 The procedure was as in Example 1 using a double-sided adhesive film with different adhesive strength of the adhesive layers, or as in Example 2 by applying an adhesive layer to the underlayer (U) on the production side, but the adhesive force of the adhesive layer to be bonded to the printing cylinder is 6 N in each case / 25 mm.
• the clichés were measured for tolerance accuracy: on the cliché surface of 762 ⁇ 1200 mm there is a fluctuation range of ⁇ 10 ⁇ m.
• a practical gray wedge which served as a copy, is distributed over the entire cliché and printed with the least possible contact pressure.
• the print image shows excellent quality; Holes or imperfections, which result in increased contact pressure and thus a deformation of fine pressure elements, were not recognizable.
• a multilayer plate with the gray wedge listed in Example 3 was copied, washed out, dried, post-exposed and after-treated.
• the printing plate thus obtained has a tolerance accuracy of ⁇ 10 ⁇ m.
• the printing cylinder is covered with a commonly used double-sided adhesive film (total thickness 0.5 mm; adhesive strength: 15 N / 25 mm; tolerance accuracy: ⁇ 25 ⁇ m).

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Photosensitive Polymer And Photoresist Processing (AREA)
• Printing Plates And Materials Therefor (AREA)
• Electrophotography Using Other Than Carlson'S Method (AREA)
• Combination Of More Than One Step In Electrophotography (AREA)
• Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)
• Materials For Medical Uses (AREA)
• Treatments Of Macromolecular Shaped Articles (AREA)
• Manufacture Or Reproduction Of Printing Formes (AREA)
• Printing Methods (AREA)
• Distillation Of Fermentation Liquor, Processing Of Alcohols, Vinegar And Beer (AREA)
• Production Of Multi-Layered Print Wiring Board (AREA)
• Filtering Materials (AREA)
• Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
• Paper (AREA)
• Discharging, Photosensitive Material Shape In Electrophotography (AREA)

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• 1986
  • 1986-10-21 DE DE19863635737 patent/DE3635737A1/de not_active Withdrawn
• 1987
  • 1987-09-16 FI FI874036A patent/FI89686C/fi not_active IP Right Cessation
  • 1987-09-28 JP JP62241022A patent/JPS63109090A/ja active Pending
  • 1987-10-20 DE DE8787115309T patent/DE3783201D1/de not_active Revoked
  • 1987-10-20 EP EP87115309A patent/EP0264894B1/fr not_active Expired - Lifetime
  • 1987-10-20 AT AT87115309T patent/ATE83708T1/de not_active IP Right Cessation
  • 1987-10-20 DK DK547587A patent/DK167665B1/da not_active IP Right Cessation

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