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
• • 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

Definitions

• the invention relates to a method for closing and / or sealing openings, cavities or gaps, such as result from the application of printing plates to forme cylinders, in particular in the region of the end or edge sections of the printing plates, by means of a sealing or sealing compound.
• the method according to the invention is particularly suitable for closing and / or sealing such openings, cavities or interspaces in intaglio printing plates, which are applied to forme cylinders and are resistant to alcoholic printing ink solvents.
• rotary printing forms For the production of rotary printing forms, it is known to wrap form cylinders with flat printing plates and to fasten them to the form cylinders in a suitable manner, for example by gluing, magnetically or mechanically by means of suitable holding and clamping elements.
• a suitable manner for example by gluing, magnetically or mechanically by means of suitable holding and clamping elements.
• only one printing plate or several printing plates can be applied one behind the other and / or next to one another on the surface of a forme cylinder.
• This method for producing rotary printing forms is becoming increasingly important, especially in rotogravure printing, because of the simple and cost-saving production and handling of gravure winding plates.
• the intaglio printing plates are preferably applied to the form cylinder by folding one or both of their end sections and hooking these folded areas into a groove of the forme cylinder provided for this purpose while simultaneously tensioning the intaglio plate.
• Such openings or gaps which form when applying printing plates to forme cylinders must be closed in a suitable manner in order to prevent penetration of printing ink, which can be done, for example, to loosen the adhesive bond between the printing plate and the forme cylinder or, in particular in gravure printing, to spray the printing ink and unwanted impression of the column can lead, and also to ensure a smooth squeegee run and thereby prevent damage to the squeegee and printing form surface.
• forehead Surfaces can be created between the forme cylinder surface and the side areas of the applied printing plate or between the printing form surface and the printing cylinder, which laterally provide metal rings that delimit the printing surface, as is usually the case in rotogravure printing, openings and gaps that can be used to avoid problems when printing against penetration must be sealed by printing ink or for other reasons.
• the present invention has for its object the openings and gaps that form when applying and fixing printing plates to forme cylinders, such as e.g. Gaps, joints, holes, cavities and the like. Sealing and / or sealing quickly and effectively with little effort, while avoiding the disadvantages known from the prior art, so that an all-round uninterrupted printing form surface is obtained which corresponds to the mechanical and withstands chemical stresses.
• the method described in DE-A-37 36 180 has considerable advantages in this regard, but is less suitable when alcoholic printing ink solvents are used.
• the object of the present invention is to provide a method which makes it possible to adapt the sealing or sealing compound to those plate types which have resistance to alcoholic printing ink solvents, the adhesion of these compounds in the cured state in the gap of the plate being said to be sufficiently great to to perform their function during the printing process.
• the sealing and sealing compound should also be clean again after printing and can be removed from the plate without residues, without damaging the printing plate.
• the invention relates to a method for closing and / or sealing openings, cavities or intermediate spaces which are formed when printing plates resistant to alcoholic printing ink solvents are applied to a forme cylinder, by means of a sealing or sealing compound, which is characterized in that as Sealing or sealing compound is a light-curable composition which consists essentially of a photopolymerizable mixture (a) 10 to 60% by weight of at least one photopolymerizable, ethylenically unsaturated low molecular compound and (b) 90 to 40% by weight of at least one copolymerizable oligomeric or polymeric binder which is compatible with the photopolymerizable low molecular weight compounds of component (a), where the sum of the percentages mentioned under (a) and (b) is 100, and additionally (c) 0.01 to 10% by weight, based on the total amount of components (a) and (b), of at least one photopolymerization initiator, such as (d) optionally customary auxiliaries and additives in an amount such that,
• the sealing or sealing compounds can additionally contain an inhibitor against thermal polymerization and an addition of 0.1 to 2% by weight, based on the total amount of components (a) + (b), of a paraffin.
• component (a) preference is given to using at least one compound from the group of the vinylaromatics and the hydroxyl-free esters of acrylic acid or methacrylic acid with mono- or polyhydric alcohols as component (a), styrene and / or esters of acrylic acid or methacrylic acid having a 1 to 12 Monoalkanol containing carbon atoms are particularly preferred.
• preferred copolymerizable oligomeric or polymeric binders are unsaturated polyesters and esterification products of di- or polyepoxides with acrylic acid or methacrylic acid.
• Fine-particle oxidic fillers which are also advantageous for the process according to the invention are preferably aluminum hydroxide and silica with particle diameters between 0.01 and 10, preferably 0.01 and 5 ⁇ m.
• alcoholic printing ink solvents are understood to be those flexographic or gravure printing ink solvents which predominantly consist of lower Alcohols, preferably consisting of ethanol, may optionally contain 5 to 20% by weight of an alkyl acetate, preferably an ethyl, n-propyl or i-propyl acetate, or water.
• sealing or sealing compounds to be used according to the invention also prevents the penetration of even low-viscosity printing ink into the openings, cavities or interspaces mentioned, while avoiding the disadvantages resulting therefrom.
• adhesion of the sealing and sealing compounds used according to the invention in the hardened state in the gap of the plate ensures trouble-free printing. After printing, the sealing and sealing compound can also be removed from the plate without leaving any residue and without damaging it.
• the openings, voids or gaps closed and / or sealed by the process according to the invention are outstandingly chemically and mechanically stable and durable under the requirements and stresses during printing, show no weaknesses and that those produced by the process according to the invention
• Rotogravure printing forms allow the squeegee to slide smoothly, smoothly and smoothly on the printing form surface without damaging it.
• the method according to the invention is particularly advantageous since it can be used universally.
• the sealing or sealing compound to be used according to the invention is simple and easy to process in the method according to the invention. On the one hand, it can be distributed uniformly in the gap cavity, on the other hand, the sealing of the gap cavity on the end faces of the cylinder is possible without additional expensive measures having to be taken.
• the method according to the invention is suitable for closing and / or sealing any kind of openings, cavities or gaps in the case of printing plates mounted on forme cylinders, it is particularly suitable and can be used without problems and advantageously when closing and / or sealing small or narrow gaps, joints, other openings, spaces and the like.
• the usual photopolymerizable, ethylenically unsaturated, low molecular weight compounds include vinyl aromatics, such as styrene, esters of acrylic acid and / or methacrylic acid, preferably those with monoalcohols with 1 to 12, in particular 1 to 8 Carbon atoms as component (a), as they are known as such.
• Preferred monomers are those whose photopolymerizable ethylenic double bonds are activated by conjugation or proximity to O, N or 5 atoms.
• the photopolymerizable ethylenically unsaturated low-molecular compounds (a) to be used according to the invention can be both monofunctional and multifunctional, ie they can contain one or more photopolymerizable, ethylenic double bonds in the molecule.
• the photopolymerizable, ethylenically unsaturated low molecular weight compounds to be used according to the invention as component (a) of the sealing compositions include, inter alia, the N-vinyl compounds and the derivatives of ⁇ , ⁇ -olefinically unsaturated mono- or dicarboxylic acids.
• acrylic acid and methacrylic acid are particularly important.
• Particularly advantageous as photopolymerizable monomers are derivatives of ⁇ , ⁇ -olefinically unsaturated carboxylic acids, in particular derivatives of acrylic or methacrylic acid, such as their hydroxyl-free esters with polyhydric alcohols, e.g. Hexanediol diacrylate, butanediol dimethacrylate, trimethylolpropane triacrylate and / or tripropylene glycol diacrylate.
• the selection of the photopolymerizable low molecular weight compounds used as component (a) depends, inter alia, on the type of polymeric binder used as component (b) with which the photopolymerizable low molecular weight compounds are to be compatible, and also on the desired properties of the cured sealing compound.
• the photopolymerizable low molecular weight compounds can be used alone or in a mixture with one another. For example, it is possible to vary the mechanical properties of the hardened sealing compound and thus sealed gaps and to adjust them to the desired extent via the type and amount of the monomers used or, if monomer mixtures are used, also via the mixing ratio of the monomers with one another.
• the sealing compounds to be used for the process according to the invention generally contain 10 to 60, preferably 20 to 50% by weight, based on the total amount of components (a) + (b), of the photopolymerizable low molecular weight compounds (a).
• the viscosity of the sealing compound can also be adjusted and varied via the amount of photopolymerizable low molecular weight compounds (a).
• the sealing compositions to be used for the process according to the invention contain, as component (b), at least one copolymerizable oligomeric or polymeric binder which is compatible with the photopolymerizable low molecular weight compounds of component (a).
• the polymeric binder is selected so that it is resistant to the alcoholic printing ink solvents commonly used and customary in gravure printing.
• Unsaturated polyesters have proven useful as copolymerizable polymeric binders (b) which are particularly advantageous for the process according to the invention.
• Unsaturated polyesters can usually be obtained by polycondensation of ⁇ -unsaturated polybasic carboxylic acids, especially dicarbon produce acids or their anhydrides with polyhydric, preferably dihydric alcohols. Some of the ⁇ -unsaturated dicarboxylic acids can be replaced by aromatic and / or saturated dicarboxylic acids. Examples of suitable unsaturated dicarboxylic acids are: maleic acid, fumaric acid, itaconic acid, citraconic acid or mesaconic acid. Examples of aromatic dicarboxylic acids are phthalic acid, isophthalic acid and terephthalic acid. For example, succinic acid, glutaric acid, ⁇ -methylglutaric acid, adipic acid or sebacic acid can also be used as saturated dicarboxylic acids.
• dihydric alcohols such as e.g. Ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol or 2,2-dimethylpropanediol-1,3 and, in certain amounts, also higher-functional alcohols, such as e.g. Gycerin, pentaerythritol or trimethylolpropane.
• dihydric alcohols such as e.g. Ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol or 2,2-dimethylpropanediol-1,3 and, in certain amounts, also higher-functional alcohols, such as e.g. Gycerin, pentaery
• Particularly preferred unsaturated polyesters are those based on phthalic acid / maleic acid / ethylene glycol / propylene glycol, which are commercially available, for example, in a styrenic solution (with about 35% by weight of styrene).
• Such standard polyester resins generally have viscosities between 300 and 2000 mPa ⁇ s (at 23 ° C.) as 30 to 50% styrene solutions and can be mixed with other polyester resins, for example those based on adipic acid / phthalic acid / maleic acid / Di -propylene glycol / propylene glycol, which are also commercially available in styrenic solution (e.g. with approx. 25% by weight styrene content) and after the polymerization alone have significantly lower tensile strengths and glass transition temperatures which are below room temperature, elasticize or make them more flexible what is known to the expert. Mixtures of these two types of polyester are preferred.
• Suitable copolymerizable oligomeric binders (b) are in particular esterification products of di- or polyepoxides with acrylic acid and or methacrylic acid.
• the di- and polyepoxides on which these esterification products are based are, in particular, those based on bisphenol A, such as are obtained, for example, by condensation of at least 2 moles of epichlorohydrin per mole of bisphenol A, which are obtained using dicarboxylic acids, such as, for example, Phthalic acid can be chain extended.
• those based on other diols or polyols are also suitable as di- or polyepoxides.
• the di- or polyepoxides can with acrylic acid and / or methacrylic acid to the preferably epoxy-free esterification products of the above mentioned type are implemented, which then contain an average of about two (meth) acrylic ester groups per molecule.
• component (b) preference is given to using those copolymerizable oligomeric and polymeric binders which are soluble in the photopolymerizable, ethylenically unsaturated low-molecular weight compounds used as component (a).
• component (b) such copolymerizable oligomeric and / or polymeric binders which are only dispersible in the photopolymerizable low molecular weight compounds of component (a), as long as the photopolymerizable low molecular weight compounds and the oligomeric and / or polymeric binders are combined are compatible and can be processed into a homogeneously flowable mixture.
• the proportion of copolymerizable oligomeric and / or polymeric binders (component (b)) in the total amount of components (a) + (b) is generally in the range from 90 to 40% by weight, in particular in the range from 80 to 50% .-% based on the total amount of components (a) + (b).
• the sealing compounds to be used for the process according to the invention contain as component (c) one or more photopolymerization initiators, in particular in an amount of 0.01 to 10, preferably 0.1 to 2 wt .-%, based on the total amount of components (a) + (b).
• the compounds which are customary and known per se as photoinitiators for light-curable compositions are suitable for this purpose.
• benzoin and benzoin derivatives such as benzoin alkyl ethers, in particular with 1 to 8 carbon atoms in the alkyl radical, for example benzoin monomethyl ether or benzoin isopropyl ether, ⁇ -hydroxymethylbenzoin and its alkyl ethers, such as ⁇ -hydroxymethylbenzoin methyl ether or ⁇ -methylbenzoin and its ether;
• Benzil and benzil derivatives in particular benzil monoketals, such as benzil dimethyl ketal, benzil methyl ethyl ketal or benzil methyl benzyl ketal;
• the acylphosphine compounds effective as photoinitiators as described, for example, in DE-OSes 28 30 927, 29 09 994, 30 20 092, 30 34 697, 31 14 314 and 31 33 419, and examples of which are 2,4, 6-trimethylbenzoyldiphenylphosphine oxide, the 2,4,6-trimethyl
• auxiliaries and additives can be used as component (d) in amounts such that, when mixed with components (a) to (c), they give transparent mixtures for long-wave UV light.
• finely divided oxidic fillers the particle size of these fillers generally being between 0.01 and 10, preferably 0.01 to 5 ⁇ m.
• examples of such fillers are colloidal or hydrophobized silicon dioxide, microtalkum, micro-mica, kaolin, aluminum oxides and aluminum hydroxides. Silicon dioxide (e.g. Aerosil® from Degussa) and aluminum hydroxide (e.g. Martinal® from Martinswerk) and mixtures thereof are particularly preferred.
• aluminum hydroxide of the hydrargillite type for example if it has grain sizes (80%) between 0.2 and 3.0 ⁇ m or a plate structure, can be particularly advantageous. In addition to reducing the polymerisation loss and increasing the strength, smooth surfaces and a significantly reduced tendency to crack during curing are obtained. In addition, there are only slight differences between the refractive index of the aluminum hydroxide and that of the resin component (b) or its mixture with component (a).
• highly disperse silicon dioxide can contribute to the thickening and thixotropy of the mixture of components (a) + (b), serve as sedimentation inhibitors for other fillers and increase the strength when hardened.
• Hydrophilic and hydrophobic highly disperse types of silicon dioxide which have particle sizes of about 12 or 14 nm, for example, can be particularly advantageous.
• the hydrophobic highly disperse types of silica are generally preferred for unsaturated polyester resins.
• Fillers can generally be added in amounts of up to 70% by weight, based on the total amount of the sealing compound.
• auxiliaries and additives can be added to the compositions to be used according to the invention, such as paraffin (for example a paraffin with a solidification point between 56 to 58 ° C.), generally in amounts of 0.1 to 2% by weight, based on the Total amount of components (a) + (b), or polymerization inhibitors, for example so-called inhibitors against thermal polymerization, such as hydroquinone, hydroquinone deri vate, 2,6-di-tert-butyl-p-cresol, nitrophenols, N-nitrosoamines, such as N-nitrosodiphenylamine, or the salts, in particular the alkali and aluminum salts, of N-nitrosocyclohexylhydroxylamine.
• paraffin for example a paraffin with a solidification point between 56 to 58 ° C.
• polymerization inhibitors for example so-called inhibitors against thermal polymerization, such as hydroquinone, hydroquinone deri vate, 2,6-d
• Plasticizers can be helpful for visual observation during gap filling and the assessment of the gap closure.
• plasticizers are low molecular weight compounds, such as the known phthalic acid esters, or compounds containing hydroxyl groups, such as glycerol, ethylene glycol and the like, which are compatible with components (a) and (b) of the sealing compounds according to the invention.
• the light-curable sealing compounds to be used for the process according to the invention are suitable for the gap closure in all gravure printing plates which can be clamped on the forme cylinder of a sheet-fed or roll rotogravure printing machine, such as, for example, the conventional gravure printing plates made of metal.
• the closure compositions according to the invention are particularly advantageous for the gap closure in gravure printing plates mounted on forme cylinders with plastic printing layers which are resistant to alcoholic printing ink solvents.
• a plastic layer is applied to a suitable printing layer support, into which the ink-absorbing depressions (cells) are made.
• These cells may have been formed in the plastic printing layer by mechanical engraving or laser engraving (see, for example, DE-A-27 52 500 or DE-A-30 28 098) or, in the case of photopolymer gravure printing plates, by imagewise exposure and development have been introduced into the photosensitive plastic printing layer (cf. DE-A-20 61 287, DE-A-31 28 949 and DE-A-31 28 951).
• the light-curable sealing compound to be used according to the invention is very advantageous in gravure winding plates for closing the gap, as is formed when these winding plates are clamped onto a form cylinder between the ends of the gravure plate.
• rotogravure plates are understood to mean the finished rotogravure plates in which the ink-guiding depressions have already been introduced, as well as the rotogravure plate blanks in which the cells have not yet been formed.
• the sealing compound for closing the gaps which result when the intaglio printing plates are clamped onto the forme cylinders can be introduced into the gap by any suitable methods or processes, provided that a uniform and complete filling of the gap cavity is ensured.
• sealing or sealing compositions can, for example, in a very simple manner by simply applying the compositions, for example from a tube, cartridge or similar metering device, to the areas of the printing plates and / or forme cylinders to be sealed and simple mechanical pressing and pressing or pressing into the openings or cavities to be closed, for example using a spatula, scraper or the like. Excess sealing material can then be easily removed by simply wiping off the printing form surface or the end faces of the printing form cylinder thus obtained.
• Post-processing can often be omitted; As a rule, however, it is expedient to smooth the surface of the hardened mass by mechanical finishing, for example by grinding, milling and / or polishing, and to adapt it to the contour of the cylinder. No special devices or expenditure are required to remove the printing plates from the forme cylinder.
• the extent of the adhesion can be controlled by changing the quantitative ratios of components (a) + (b), preferably the different polymer proportions of components (b). This is also a particular advantage of the method according to the invention. Inserted printing plates can be reused without restriction.
• the light-curable sealing compound is irradiated with actinic light for curing.
• actinic light sources which can emit light in the actinic wavelength range effective for the sealing compounds, in particular in a wavelength range of approximately 250 to 450 nm, can be used, e.g. Carbon arc lamps, actinic or superactinic fluorescent tubes, low, medium or high pressure mercury lamps, which can optionally be doped, xenon lamps or lasers with a high UV component.
• compositions to be used according to the invention for closing and / or sealing openings, cavities or gaps in printing plates applied to forme cylinders have both high stability with respect to the solvents and solvent mixtures usually used in printing inks, in particular those of a polar nature, such as alcohols, esters, ketones, as also pronounced variability with regard to the application (flow behavior, spreadability, adhesion, surface smoothness, mechanical workability) by adding different amounts of one or more oxidic fillers.
• compositions to be used according to the invention before and after curing can be adapted to the application requirements within particularly wide limits.
• the mass is cured by exposure to ultraviolet light.
• Example 21.7 g of a highly disperse silicon dioxide and 229 g of a finely divided aluminum hydroxide were incorporated into the liquid photosensitive mixture described in Example 1 with stirring.
• the paste-like mass obtained after complete homogenization and degassing could easily be introduced into the cavities and joints to be sealed by filling or with the help of a tube.
• the gap sealing compound was cured as described in Example 1.
• the syrupy mass obtained in this way could be used to seal joints and cavities. It could easily be applied by injection.
• the curing was carried out by irradiation with ultraviolet light.
• the mass was degassed as usual. It was particularly easy to inject into the joints to be sealed and, after curing with UV light, showed very good resistance to ethanol.
• the slightly syrupy mixture is homogenized and degassed under reduced pressure.
• the photopolymerizable composition thus obtained is used to close the opening between the two ends of a printing plate clamped on a cylinder. Because of its good flow behavior, the mass is particularly suitable for injection by means of a hose or tube system into narrow and / or difficult to access cavities or openings.
• the mass is produced essentially as described in Example 5.
• 40 g of a highly disperse silicon dioxide are added before the homogenization and degassing step.
• the viscous mass obtained in this way can be introduced into the cavities to be sealed in addition to by means of wide-lumen application systems. When cured, it shows excellent adhesion to polymer layers and very good machinability.
• the basic batch from Example 5 is thickened by adding 80 g of a highly disperse silicon dioxide and 2000 g of a finely divided aluminum hydroxide.
• the photocurable sealing compound thus obtained can be conveniently applied from a tube.
• the basic batch from Example 5 is modified by adding 80 g of a highly disperse silicon dioxide and 3000 g of a finely divided aluminum hydroxide.
• the pasty sealing compound obtained in this way can be applied particularly easily by filling. When cured, it shows excellent mechanical properties.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Sealing Material Composition (AREA)
• Macromonomer-Based Addition Polymer (AREA)
• Supply, Installation And Extraction Of Printed Sheets Or Plates (AREA)
• Inks, Pencil-Leads, Or Crayons (AREA)

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Citations (4)

• 1989
  • 1989-06-20 DE DE19893920093 patent/DE3920093A1/de not_active Withdrawn
• 1990
  • 1990-05-24 CA CA 2017497 patent/CA2017497A1/fr not_active Abandoned
  • 1990-06-11 EP EP19900110994 patent/EP0406585A3/de not_active Withdrawn
  • 1990-06-13 JP JP15290590A patent/JPH0334855A/ja active Pending

Patent Citations (4)

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