Classifications

• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
  • C11D7/50—Solvents
  • C11D7/5004—Organic solvents
  • C11D7/5013—Organic solvents containing nitrogen
• • 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
  • B41C1/1041—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme by modification of the lithographic properties without removal or addition of material, e.g. by the mere generation of a lithographic pattern
• • 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
  • B41N3/00—Preparing for use and conserving printing surfaces
  • B41N3/006—Cleaning, washing, rinsing or reclaiming of printing formes other than intaglio formes
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
  • C11D3/16—Organic compounds
  • C11D3/20—Organic compounds containing oxygen
  • C11D3/2003—Alcohols; Phenols
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D3/00—Other compounding ingredients of detergent compositions covered in group C11D1/00
  • C11D3/16—Organic compounds
  • C11D3/20—Organic compounds containing oxygen
  • C11D3/2068—Ethers
• • 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
  • B41C1/1008—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme by removal or destruction of lithographic material on the lithographic support, e.g. by laser or spark ablation; by the use of materials rendered soluble or insoluble by heat exposure, e.g. by heat produced from a light to heat transforming system; by on-the-press exposure or on-the-press development, e.g. by the fountain of photolithographic materials
  • B41C1/1025—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme by removal or destruction of lithographic material on the lithographic support, e.g. by laser or spark ablation; by the use of materials rendered soluble or insoluble by heat exposure, e.g. by heat produced from a light to heat transforming system; by on-the-press exposure or on-the-press development, e.g. by the fountain of photolithographic materials using materials comprising a polymeric matrix containing a polymeric particulate material, e.g. hydrophobic heat coalescing particles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C2210/00—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation
  • B41C2210/04—Negative working, i.e. the non-exposed (non-imaged) areas are removed
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C2210/00—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation
  • B41C2210/08—Developable by water or the fountain solution
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C2210/00—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation
  • B41C2210/22—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation characterised by organic non-macromolecular additives, e.g. dyes, UV-absorbers, plasticisers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C2210/00—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation
  • B41C2210/24—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation characterised by a macromolecular compound or binder obtained by reactions involving carbon-to-carbon unsaturated bonds, e.g. acrylics, vinyl polymers
• • 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
  • B41N3/00—Preparing for use and conserving printing surfaces
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D2111/00—Cleaning compositions characterised by the objects to be cleaned; Cleaning compositions characterised by non-standard cleaning or washing processes
  • C11D2111/10—Objects to be cleaned
  • C11D2111/14—Hard surfaces
  • C11D2111/20—Industrial or commercial equipment, e.g. reactors, tubes or engines
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
  • C11D7/22—Organic compounds
  • C11D7/32—Organic compounds containing nitrogen
  • C11D7/3218—Alkanolamines or alkanolimines
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
  • C11D7/22—Organic compounds
  • C11D7/32—Organic compounds containing nitrogen
  • C11D7/3263—Amides or imides
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
  • C11D7/22—Organic compounds
  • C11D7/32—Organic compounds containing nitrogen
  • C11D7/3281—Heterocyclic compounds

Definitions

• the present invention relates to a cleaning method for recycling the lithographic substrate of a printing master.
• ink and an aqueous fountain solution are supplied to the surface of a printing master which contains ink-accepting (oleophilic) and water-accepting (hydrophilic) areas.
• the inked image pattern is then transferred from the surface of the master to a blanket cylinder having a compressible surface. From the blanket cylinder the image is impressed onto paper.
• the master is typically a printing plate which carries an image on a dimensionally stable substrate such as an aluminium sheet.
• the imaged aluminium plate is secured to the plate cylinder of a printing press by a mechanical lock-up mechanism which defines positional registration between the plate and the surface of the cylinder. After the end of the press-run, the mechanical lock-up system is released so that the printing plate carrying the printed image can be removed and discarded and another printing plate can be positioned and locked into place. A new print job can then be started.
• Printing masters are generally obtained by the so-called computer-to-film method wherein each colour selection is transferred to graphic arts film using an image-setter. After processing, the film can be used as a mask for the exposure of an imaging material called plate precursor and after plate processing, a printing plate is obtained which can be used as a master. These steps are usually performed in dedicated exposure and processing equipment and the printing plates are then transported to the printing press and attached to the printing cylinder by press operators using a lock-up mechanism built into the cylinder itself. Although the attachment of the printing cylinder is generally a manual operation, robotic means have been developed for positioning and securing the printing plates.
• a printing plate precursor is mounted on a printing press, image-wise exposed, optionally developed, and then used as a printing master and finally removed from the press and disposed of, thus requiring a new plate material for each image.
• An example of this technology is the well-known Heidelberg Model GTO-DI, manufactured by Heidelberg Druckmaschinen AG (Germany) which is described in detail in US 5,339,737.
• a drawback of this method is the need to use a new plate for each press-run, thus increasing the cost of the printing process.
• a second type of on-press imaging systems the same lithographic substrate is used in a plurality of press-runs (hereinafter called printing cycles).
• a heat-sensitive or photosensitive layer is coated on the lithographic substrate to make a printing plate precursor and after image-wise exposure and optional development a printing master is obtained.
• the ink-accepting areas of the printing master are removed from the lithographic substrate in a cleaning step so that the substrate is recycled and can be used in a next cycle of coating, exposing and printing without the need to mount a new plate on the cylinder. Examples of such on-press coating and on-press imaging systems are described in e.g.
• the coating comprises hydrophobic thermoplastic polymer particles in a hydrophilic binder.
• a typical lithographic surface is mechanically as well as chemically quite vulnerable.
• a lithographic surface consists generally of a micro-pore structure in order to differentiate the spreading properties of the ink and the fountain.
• Anodised aluminium plates comprise a lithographic surface containing one or more metal oxides on which absorption phenomena can take place. These metal oxides are very susceptible to chemical conversion into forms which are no longer lithographically active.
• micro-porosity of a lithographic surface is also highly susceptible to mechanical damage.
• ink and the coated imaging layer penetrate in the micro-pore structure, it is necessary to carry out a vigorous cleaning so as to avoid phantom images in the subsequent printing cycle, which are due to an insufficient removal of the previous image.
• the known cleaning liquids typically contain solvents which are harmful to hoses, pumps and sealings and/or require a very thorough rinsing with water because these liquids are not compatible with the coating step in the next printing cycle.
• the above objects are obtained by the method of claim 1.
• the cleaning liquid defined in claim 1 effectively removes the ink-accepting areas of the printing master defined in claim 1. No ghost images are observed after several (>10) print cycles of coating, exposure, printing and cleaning. Rubber hoses and seals are not affected by the cleaning liquid and low amounts of water suffice in the optional rinsing step.
• the cleaning liquid used in the method of the present invention contains an amide.
• Suitable examples of the amide are : N,N-dimethylacetamide, N-methylacetamide, N,N-diethylacetamide, N,N-dipropylacetamide, N,N-dimethylpropionamide, N,N-diethylbutyramide, N-methyl-N-ethyl-propionamide, N-methylformamide, N,N-dimethylformamide, 1,3-dimethyl-2-imidazolidinone, and acetohydroxamic acid.
• Dimethylformamide and especially 2-N-methyl-pyrrolidone are highly preferred.
• the amide can be a liquid amide which can be supplied to the printing master as an essentially pure liquid. More preferably, the cleaning liquid is an aqueous solution comprising an amide in an amount between 1% and 50% by weight, more preferably between 2% to 30 % by weight and most preferably between 5% and 15 % by weight.
• the cleaning liquid also contains an alkanolamine in a concentration of at most 20% by weight.
• alkanolamine are : diethanolamine, diethylethanolamine, diisopropanolamine, monoethanolamine, monoisopropanolamine, triethanolamine, triisopropanolamine, aminoethoxyethanol, aminoethylaminoethanol, monopropanolamine, methylaminoethanol, hydroxylamine, N-butyl-ethanolamine, N-ethyldiethanolamine, diglycolamine, and dimethylglyoxime.
• Monoethanolamine is highly preferred.
• the cleaning liquid preferably also comprises a surfactant in an amount between 0.001% and 5% by weight.
• the above cleaning liquids are very suitable for removing the ink-accepting areas from a printing master which is obtained by coating a hydrophilic substrate with a coating solution containing hydrophobic thermoplastic polymer particles and a hydrophilic binder.
• the imaging material thus obtained is negative-working, i.e. hydrophobic areas are formed upon exposure. These areas define the printing areas of the master. It is believed that the applied heat induces a coagulation of the hydrophobic polymer particles, thereby forming a hydrophobic phase, whereas the hydrophobic polymer particles remain unchanged in the non-heated areas. Coagulation may result from heat-induced softening or melting of the thermoplastic polymer particles.
• the cleaning liquids of the present invention are capable of removing the ink remaining on the printing areas as well as the hydrophobic phase itself which gives rise to the ink-accepting properties of the printing areas.
• the method of the present invention comprises two cleaning steps : first, an amide is supplied to the master so as to remove the ink and subsequently, an alkanolamine is used to remove the hydrophobic areas.
• other solvents such as an alcohol, e.g. benzylalcohol or 2-butoxyethanol, can be supplied to the master, either as a mixture with the amide or alkanolamine, or in a separate cleaning step.
• the imaging material used in the present invention preferably contains hydrophobic thermoplastic polymer particles having an average particle size between 40 nm and 2000 nm, and more preferably between 40 nm to 200 nm, so as to improve sensitivity and throughput and to avoid scumming.
• the polymer particles preferably have a coagulation temperature above 50°C and more preferably above 70°C. There is no specific upper limit to the coagulation temperature of the polymer particles, however the temperature should be sufficiently below the decomposition temperature of the polymer particles. Preferably the coagulation temperature is at least 10°C below the temperature at which the decomposition of the polymer particles occurs.
• thermoplastic hydrophobic polymer particles for use the present invention have a Tg above 80°C.
• the weight average molecular weight of the polymers may range from 5,000 to 5,000,000 g/mol.
• the polymer particles are selected from the group consisting of polyvinyl chloride, polyvinylidene chloride, polyesters, polyurethanes, polyacrylonitrile, polyvinyl carbazole etc., and copolymers or mixtures thereof.
• the most preferred examples are polystyrene and polymethylmethacrylate or copolymers thereof.
• the polymer particles are present as a dispersion in the coating solution and may be prepared by the methods disclosed in US 3,476,937. Another method especially suitable for preparing an aqueous dispersion of the thermoplastic polymer particles comprises:
• Suitable hydrophilic binders for use in the present invention are preferably water-soluble (co)polymers for example synthetic homo- or copolymers such as polyvinylalcohol, a poly(meth)acrylic acid, a poly(meth)acrylamide, a polyhydroxyethyl(meth)acrylate, a polyvinylmethylether or natural binders such as gelatin, a polysaccharide such as e.g. dextran, pullulan, cellulose, arabic gum, alginic acid, inuline or chemically modified inuline.
• water-soluble (co)polymers for example synthetic homo- or copolymers such as polyvinylalcohol, a poly(meth)acrylic acid, a poly(meth)acrylamide, a polyhydroxyethyl(meth)acrylate, a polyvinylmethylether or natural binders such as gelatin, a polysaccharide such as e.g. dextran, pullulan,
• the coating solution preferably contains surfactants which can be anionic, cationic, non-ionic or amphoteric.
• Perfluoro surfactants are preferred. Particularly preferred are non-ionic perfluoro surfactants. Said surfactants can be used alone or preferably in combination.
• the coverage of the coated layer ranges preferably from 0.3 to 20 g/m 2 , more preferably from 0.5 to 5 g/m 2 .
• the amount of hydrophobic thermoplastic polymer particles contained in the coated layer is preferably between 50 and 90 % by weight and more preferably between 60 and 80 % by weight of the total weight of said layer.
• the substrate used in the present invention can be a plastic support or a ceramic but is preferably a metal such as aluminium.
• the substrate has a hydrophilic surface and is preferably characterised by a roughness value of at least 0.2 ⁇ m, more preferably of at least 0.3 ⁇ m, e.g. electrochemically and/or mechanically grained and anodised aluminium.
• the substrate can be a sheet-like material such as a plate but, alternatively, the coating solution may be applied directly to the plate cylinder of a rotary printing press, said cylinder thereby acting as the substrate.
• the lithographic substrate can also be a seamless sleeve printing plate, obtained by e.g. soldering a plate into a cylindrical form by means of a laser. The sleeve then can be slid around the plate cylinder instead of mounting a conventional printing plate. More details on sleeves are given in "Grafisch Nieuws" , 15, 1995, page 4 to 6.
• the exposure of the imaging material obtained by coating the above coating solution on the lithographic substrate can be carried out by means of direct thermal recording using e.g. a thermal head, or by irradiation with high intensity light.
• the heat-sensitive material preferably comprises a compound capable of converting light into heat, preferably a compound having sufficient absorption in the wavelength range of the light source used for image-wise exposure.
• Particularly useful compounds are for example dyes and in particular infrared dyes as disclosed in EP-A 908 307 and pigments and in particular infrared pigments such as carbon black, metal carbides, borides, nitrides, carbonitrides, bronze-structured oxides and oxides structurally related to the bronze family but lacking the A component e.g.
• WO 2.9 It is also possible to use conductive polymer dispersions such as polypyrrole or polyaniline-based conductive polymer dispersions.
• conductive polymer dispersions such as polypyrrole or polyaniline-based conductive polymer dispersions.
• the lithographic performance and in particular the print endurance obtained depends i.a. on the heat-sensitivity of the imaging material. In this respect it has been found that carbon black yields very good and favourable results.
• Image-wise exposure in the method of the present invention is preferably an image-wise scanning exposure involving the use of a laser or L.E.D.
• a laser or L.E.D Preferably used are lasers that operate in the infrared or near-infrared, i.e. wavelength range of 700-1500 nm. Most preferred are laser diodes emitting in the near-infrared.
• a grained and anodised aluminium plate is mounted on the plate cylinder of a rotary printing press.
• the coating solution described above is sprayed on the hydrophilic lithographic surface of the plate, so as to form a continuous imaging layer.
• Preferred values of the spraying parameters have been defined in EP-A no. 99203064 and EP-A no. 99203065, both filed on 15th September 1999.
• the imaging layer is then image-wise exposed whereby the exposed areas are converted to hydrophobic ink-accepting areas while the unexposed areas remain hydrophilic.
• the hydrophobic areas define the printing areas of the master.
• printing is started by applying ink and a fountain solution to the printing master.
• ink and a fountain solution In order to dissolve and remove the non-exposed areas of the coated layer effectively, only fountain solution is preferably supplied during a few revolutions of the press (about 10), and then also ink is fed to the plate.
• the lithographic substrate is recycled by treatment with a cleaning liquid as described above. Finally, the substrate can be rinsed and dried and then, a new printing cycle can be started by spraying the coating solution to the recycled substrate.
• the cleaning step can be executed in a cleaning unit similar to the known blanket cleaning system.
• a cloth is moistened with the cleaning liquid, contacted with the printed plate during 1 to 50, more preferably during 2 to 10 revolutions with a contacting pressure between 10 4 and 6x10 5 Pa at a rotation speed in the range of 2 to 50 m/min. Afterwards the contact between the printing surface and the cleaning cloth is disrupted and the cloth is transported until a dry and clean part of the cloth is available.
• the cleaner can also be applied by spraying, coating or jetting the cleaning liquid on the lithographic substrate or on the cloth.
• the removal of the ink-accepting areas can also be effected with another absorbing medium than a cloth.
• Cleaning can also be effected by combining the treatment with the cleaning liquid of the present invention with other means of mechanical rubbing such as a rotating brush or by jetting water or a volatile medium such as air, a solvent or dry ice pellets. Also vacuum extraction can be used during the cleaning treatment.
• the cleaning step is preferably followed by a rinsing step, wherein water is sprayed onto the substrate.
• the plate can then be dried with a cloth, e.g. using the same blanket cleaning system described above.
• the rinsing step involves only a slight moistening of the lithographic surface, i.e. not more than 50 ml/m 2 of water is supplied to the plate.
• the rinsing step may be repeated several times, preferably between 2 to 5 times.
• the steps of the method of the present invention are preferably performed on-press.
• the lithographic substrate can also be mounted on a drum in a dedicated coating apparatus (off-press coating) and subsequently be mounted on a plate setter for image-wise exposure (off-press exposure).
• the printing master thus obtained can be mounted on a press cylinder and printing is started by supplying ink and a fountain solution.
• the plate can be cleaned as described above, either on-press or in a dedicated cleaning apparatus, and the recycled substrate can then be used again in a next printing cycle.
• a 0.30 mm thick aluminium foil was degreased by immersing the foil in an aqueous solution containing 5 g/l of sodium hydroxide at 50°C and rinsed with demineralised water.
• the foil was then electrochemically grained using an alternating current in an aqueous solution containing 4 g/l of hydrochloric acid, 4 g/l of hydroboric acid and 5 g/l of aluminium ions at a temperature of 35°C and a current density of 1200 A/m 2 to form a surface topography with an average center-line roughness Ra of 0.5 m ⁇ .
• the aluminium foil was etched with an aqueous solution containing 300 g/l of sulphuric acid at 60°C for 180 seconds and rinsed with demineralised water at 25°C for 30 seconds.
• the foil was subsequently subjected to anodic oxidation in an aqueous solution containing 200 g/l of sulphuric acid at a temperature of 45°C, a voltage of about 10 V and a current density of 150 A/m 2 during about 300 seconds to form an anodic oxidation film of 3.0 g/m 2 of Al 2 O 3 , then washed with demineralised water and post-treated with a solution containing polyvinylphosphonic acid and subsequently with a solution containing aluminium trichloride, rinsed with demineralised water at 20°C during 120 seconds and dried.
• a 2.61% solution in water was prepared by mixing polystyrene latex, dye I and a hydrophilic binder. After spraying and drying, the resulting layer contained 75% of the polystyrene latex, 10% of the dye I and 15% of Glascol E 15TM. Glascol E 15 is a polyacrylic acid, commercially available at N.V. Allied Colloids Belgium.
• the above aluminium substrate was mounted on a drum, rotating at a line speed of 164 m/min.
• the above solution was coated on the substrate by means of an air-assisted spray nozzle, type SUJ1, available from Spraying Systems Belgium (Brussels).
• the spray nozzle was mounted at a distance of 80 mm from the substrate and the flow rate of the spray solution was set at 7 ml/min.
• the nozzle was moved at a speed of 1.5 m/min and an air pressure of 7.58x10 5 Pa was used on the spray head.
• the coated layer was dried by applying hot air (70°C).
• the imaging material was exposed in a Creo 3244TM external drum plate setter at 2400 dpi and 150 rpm with a power setting of 15.5 Watt.
• the imaged plates was printed on a GTO 46 printing press with K + E 800 Skinnex ink and as fountain solution Rotamatic to a run length of 5000. The printing quality was excellent.
• the plate was mounted on a drum of a cleaning unit comparable to a typical blanket cleaning system.
• a cloth was moistened with a cleaning liquid consisting of a mixture of 80% 2-N-methylpyrrolidone and 20% ethanolamine.
• the cleaning was carried out by contacting the cloth with the printing plate at a pressure of 9x10 4 Pa during 5 revolutions of the drum.
• the cloth was rotating relative to the plate at a speed of 20 m/min.
• 30 ml/m 2 of water was sprayed on the printing plate as a rinsing liquid, followed by contacting the moistened plate with a dry and clean part of the cloth (same settings as in the cleaning step, 1 revolution).
• the cleaning liquid contained 50 % of 2-N-methylpyrrolidone and 20 % of ethanolamine. Water was added up to 100 %.
• the above cleaning liquids were tested on chemical reactivity towards rubber of the type EPDM (a terpolymer of ethylene, propylene and a non-conjugated diene), which is frequently used in blanket cleaning systems. After immersing the rubber in the cleaning liquid during 24 hours, the weight increase of the rubber (due to swelling) was measured.
• the cleaning liquids used in Examples 1, 2 and 3 caused a weight increase of 87%, 0.12% and 0.10% respectively. An increase of at most 0.12 % is regarded acceptable.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Wood Science & Technology (AREA)
• Emergency Medicine (AREA)
• Health & Medical Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Printing Plates And Materials Therefor (AREA)
• Manufacture Or Reproduction Of Printing Formes (AREA)
• Photosensitive Polymer And Photoresist Processing (AREA)
• Materials For Photolithography (AREA)

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Citations (2)

• 2000
  • 2000-01-18 EP EP00200178A patent/EP1118472B1/de not_active Expired - Lifetime
  • 2000-01-18 DE DE60015708T patent/DE60015708T2/de not_active Expired - Lifetime
• 2001
  • 2001-01-15 JP JP2001006223A patent/JP2001246725A/ja active Pending

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