Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C1/00—Forme preparation
  • B41C1/10—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme
  • B41C1/1008—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
  • B41C1/1016—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 characterised by structural details, e.g. protective layers, backcoat layers or several imaging layers
• • 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
  • B41C1/1033—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 by laser or spark ablation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C2201/00—Location, type or constituents of the non-imaging layers in lithographic printing formes
  • B41C2201/04—Intermediate layers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
  • B41C2201/00—Location, type or constituents of the non-imaging layers in lithographic printing formes
  • B41C2201/14—Location, type or constituents of the non-imaging layers in lithographic printing formes characterised by macromolecular organic compounds, e.g. binder, adhesives
• • 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
  • B41C2210/16—Waterless working, i.e. ink repelling exposed (imaged) or non-exposed (non-imaged) areas, not requiring fountain solution or water, e.g. dry lithography or driography
• • 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
  • B41C2210/20—Preparation or type or constituents of the imaging layers, in relation to lithographic printing forme preparation characterised by inorganic additives, e.g. pigments, salts
• • 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

Definitions

• the present invention relates to a heat-mode imaging material which is suitable for making a driographic printing master.
• Rotary printing presses use a so-called master such as a printing plate which is mounted on a cylinder of the printing press.
• the master carries an image which is defined by the ink accepting areas of the printing surface and a print is obtained by applying ink to said surface and then transferring the ink from the master onto a substrate, which is typically a paper substrate.
• ink as well as an aqueous fountain solution are fed to the printing surface of the master, which consists of oleophilic (i.e. ink accepting) and hydrophilic (water accepting) areas.
• driographic printing only ink is applied to the printing surface of the master, which consists of ink accepting and ink repelling areas. These ink repelling areas are often called oleophobic or ink-abhesive areas.
• Driographic plates are sometimes simply called 'dry' plates as distinct from the conventional 'wet' plates.
• Printing masters are generally obtained by the so-called computer-to-film method wherein various pre-press steps such as typeface selection, scanning, colour separation, screening, trapping, layout and imposition are accomplished digitally and each colour selection is transferred to graphic arts film using an image-setter.
• 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.
• the computer-to-press methods referred to above preferably use so-called thermal or heat-mode imaging materials, i.e. plate precursors or on-press coatable compositions which comprise a compound that converts absorbed light into heat, which then triggers the imaging mechanism of the plate precursor.
• Thermal plates offer the potential advantages of daylight handling and elimination of processing after exposure.
• the best known heat-mode driographic materials are based on ablation such as the plates disclosed in e.g. EP-A 580 393; EP-A 684 133; US 5,540,150; US 5,551,341; and US 5,379,698.
• ablative absorption of a recording layer provokes the removal of an ink-abhesive surface layer to reveal an underlying ink accepting surface.
• the recording layer is typically a thin metal layer, which is melted or vaporised upon exposure. Silicone coatings are generally used as an ink-abhesive top layer.
• this patent application claims a lithographic printing plate directly imageable by laser discharge, the plate comprising a topmost first layer and a second layer underlying the first layer, wherein the first layer is characterised by efficient absorption of infrared radiation and the first and second layer exhibit different affinities for at least one printing liquid selected from the group consisting of ink and an abhesive fluid for ink.
• this patent application only enables the making of a driographic plate wherein a silicon layer is removed by ablative absorption and cleaning. Accordingly, the driographic plates disclosed by EP-A 580 393 are characterised by the same disadvantages as described above.
• WO99/16621 describes a method for making a driographic plate wherein an ink-abhesive support is coated with an ink-accepting formulation which preferably comprises less than 25 wt.% of light absorbing compound.
• image is used in the context of driographic printing, i.e. a pattern consisting of ink accepting and ink-abhesive areas.
• the material of the present invention is negative working, meaning that the areas, which have been exposed to light, are ink accepting and that the non-exposed areas are ink-abhesive.
• the material is a "heat-mode” material, meaning that the imaging mechanism is triggered by heat, which is generated upon exposure to light by the presence of a light absorbing compound.
• the material of the present invention can be used as a driographic printing master directly after exposure without a processing step, because the material comprises a light absorbing layer, defined as the "first layer", which can be removed at the non-exposed areas by starting a pressrun.
• the removal of said first layer reveals an underlying layer having an ink-abhesive surface, said layer being defined as the "second layer”.
• No material of the second layer needs to be removed during the heat-mode exposure or during the start of the pressrun, so that the second layer can be made highly wear-resistant, enabling long press runs.
• the imaging mechanism of the materials according to the present invention is not known, but seems to result in a conversion of the surface of the material into an ink accepting phase which cannot be removed by printing, i.e. which is resistant to mechanical cleaning and is insoluble in ink.
• partial ablation of the first layer may occur during heat-mode exposure, a significant amount of the light absorbing compound is not removed by the exposure but seems to be converted into an ink accepting substance which defines a printing area on the plate.
• This conversion can be a chemical reaction of the light absorbing compound itself but also other compounds present in the material can be involved.
• the light absorbing compound may only act as a light-to-heat convertor which triggers the conversion of another compound into an ink accepting phase. Said other compound may be present in the first or the second layer.
• a preferred material according to the present invention comprises a support and provided thereon a silicone coating as a second layer and a carbon-based top layer as a first layer.
• the ink-abhesive second layer can be a self-supporting layer which acts as a support of the first layer. More preferably, the first and second layer are carried by a support. Since said support is not utilised as a printing surface, its affinity for ink is not relevant.
• the support can be opaque or transparent, the latter enabling back-side exposure.
• a preferred support is a plastic foil or a metal support.
• Suitable examples of such a plastic foil are cellulose esters such as cellulose acetate, cellulose propionate and cellulose butyrate, polyesters such as poly(ethylene terephthalate) and poly(ethylene naphtalenecarboxylate), poly(vinyl acetals), polystyrene, polycarbonate, poly(vinyl chloride) or poly-alpha-olefins such as polyethylene or polypropylene.
• Preferred examples of a metal support are steel, particularly polished stainless steel, and especially aluminium. In a highly preferred embodiment, the support can also be the surface of a press cylinder, an endless belt or a metal sleeve which may be mounted on a press cylinder before or after being applied with the first and second layer.
• the second layer contains an ink-abhesive compound, e.g. a fluoropolymer or, more preferably, a silicone.
• the second layer is a silicone coating which contains one or more components one of which is generally a linear silicone polymer terminated with a chemically reactive group at both ends and a multifunctional component as a hardening agent.
• the silicone coating is preferably crosslinked, e.g. by condensation curing, addition curing or radiation curing.
• Condensation curing can be performed by using a hydroxy-terminated polysiloxane that can be cured with a multifunctional silane.
• Suitable silanes are e.g. acetoxy silanes, alkoxy silanes and silanes containing oxime functional groups.
• the condensation curing is carried out in the presence of one or more catalyst such as e.g. tin salts or titanates.
• hydroxy terminated polysiloxanes can be cured with a polyhydrosiloxane polymer in the presence of a catalyst e.g. dibutyltindiacetate.
• Addition curing is based on the addition of Si-H to a double bond in the presence of a platinum catalyst.
• Silicone coatings that can be cured according to the addition curing thus comprise a vinyl group containing polymer, a platinum catalyst e.g. chloroplatinic acid complexes and a polyhydrosiloxane e.g. polymethylhydrosiloxane.
• Suitable vinyl group containing polymers are e.g. vinyldimethyl terminated polydimethylsiloxanes and dimethylsiloxane/vinylmethyl siloxane copolymers.
• Radiation curable coatings that can be used in accordance with the present invention are e.g. U.V. curable or electron beam curable polysiloxane polymers.
• the latter coatings preferably contain multifunctional (meth)acrylate monomers.
• the second layer may also comprise other ingredients, e.g. plasticisers, pigments, dyes, etc.
• One or more intermediate layers may be present between the first and the second layer, provided that these layers can be removed during the pressrun or optional processing steps.
• One or more intermediate layers may also be present between the second layer and the support, e.g. a layer which promotes the adhesion of the second layer to the support or which reflects incident light back to the first layer.
• On top of the first layer there may be provided a surface layer for protecting said first layer against moisture, chemicals, oxygen, mechanical impact, etc.
• the first layer which comprises the light absorbing compound is preferably very thin, i.e. having a dry layer thickness below 1 ⁇ m, preferably below 0.5 ⁇ m and even more preferably below 0.1 ⁇ m. A layer thickness of 0.01 ⁇ m may still give satisfactory results.
• the light absorbing compound used in the present invention is a compound which is capable of converting light into heat and is preferably carbon-based or organic.
• a near infrared light absorbing compound is preferred.
• Useful compounds are for example organic dyes, carbon black, graphite or soot.
• the first layer comprises the light absorbing compound as main compound, i.e. in an amount not less than 50% by weight. In even more preferred embodiments, said amount of light absorbing compound in the first layer is not less than 70% or even not less than 90% by weight. In a most preferred embodiment, the first layer consists essentially of light absorbing compound.
• the first layer of the present invention may contain a binder e.g. gelatine, cellulose, cellulose esters e.g. cellulose acetate, nitro-cellulose, poly(vinyl alcohol), poly(vinyl pyrrolidone), a copolymer of vinylidene chloride and acrylonitrile, poly(meth)acrylates, or poly(vinyl chloride).
• the first layer may further comprise additional inert compounds such as a pigment, a matting agent, a filler, wetting agents or anti-oxidising agents.
• inert shall not be understood in the meaning of "non-functional", since such inert compounds may be added to the layer to adjust certain physical properties, such as e.g. the surface roughness or the friction coefficient of the applied layer.
• the word “inert” shall rather be understood as meaning “not essential for the imaging process", though some inert compounds may have a (minor) influence on the speed and image quality of the material.
• the first layer may comprise other compounds in addition to the light absorbing compound, the amount of other reactive compounds besides the light absorbing compound is preferably less than 20% by weight.
• the feature "reactive compound” shall be understood as a compound which undergoes a (physico-)chemical reaction due to the heat generated during image-wise exposure. Examples of such reactive compounds are thermoplastic polymer latex, diazo resins, naphtoquinone diazide, photopolymers, resole and novolac resins, or modified poly(vinyl butyral) binders. More examples can be found in J. Prakt. Chem. Vol. 336 (1994), p. 377-389.
• the amount of said other reactive compounds in the first layer is less than 10% by weight and most preferably, the first layer is substantially free from reactive compounds other than the light absorbing compound.
• the words "substantially free” shall be understood as meaning that a small ineffective amount of such reactive compounds may be present in addition to the light absorbing compound. Said small ineffective amount is not essential for or does not significantly contribute to the imaging process of the material made according to the present invention. This can be tested easily by preparing a material without said small amount of reactive compounds and establishing whether the material thus obtained can still be used to make a printing master.
• the treshold value below which the amount of the other reactive compounds, besides the light absorbing compound, may be regarded as "ineffective” depends on the nature of the reactive compounds.
• the first layer can be applied by coating a solution or dispersion of the light absorbing compound using the known coating techniques. Coating of a dispersion of carbon or a solution of an organic dye, or mixtures thereof, are highly preferred embodiments of the method according to the present invention. Jet methods can be used as an alternative coating technique, whereby either a uniform layer of light absorbing compound is jet-coated on the second layer and then image-wise exposed or whereby the light absorbing compound is image-wise applied on the second layer and then rendered ink accepting by intense heating, e.g. by infrared laser exposure.
• the first layer can also be applied as a dry powder of which the light absorbing compound is the main compound, i.e. present in an amount not less than 50% by weight.
• the dry powder consists of or comprises soot as a light absorbing compound, i.e. the black carbon obtained from the incomplete combustion of organic materials such as oils, wood, natural gas, butane, acetylene, coal, wax or cork.
• soot may even be applied by contacting the support which carries the second layer with a flame obtained by burning said organic material, preferably with the colder part of the flame where combustion is incomplete, e.g. the yellow end of a candle flame. Electron microscopic images of materials made in this way show a coating of submicron soot particles.
• a preferred method for applying the first layer is rubbing in the support, which carries the second layer, with a dry powder comprising the light absorbing compound, e.g. carbon or an organic dye in powder form, or even with incompletely burned organic materials such as charcoal, a semi-burned cork, etc.
• Alternative dry coating methods can also be used, e.g. sputter-coating of carbon or direct electrostatic printing (toner jet).
• the latter technique can also be used to apply the dry powder image-wise and after intense heating, e.g. by infrared laser exposure, a printing master is obtained.
• Said infrared laser can be mounted on the saute carriage as the direct electrostatic printing head.
• said first layer may be a contiguous or a non-contiguous layer.
• a thin layer of soot is deposited by incomplete combustion, electron microscopic images reveal that on a submicron scale some areas are not covered by the soot particles.
• the feature "first layer” also embraces a non-contiguous layer, irrespective of the scale of the non-covered areas, which may be even macroscopic, e.g. in the case of image-wise application of a first layer as discussed above.
• the method of the present invention can be used in computer-to-plate (off-press exposure) or computer-to-press (on-press exposure) procedures.
• the method may also involve on-press coating, e.g. applying a first layer according to the present invention on a second layer which is carried by a support mounted on a cylinder of the printing press. Said on-press coating may also be carried out directly on the cylinder of a printing press, said cylinder acting as a support.
• the first layer can also be applied by using a transfer material, which comprises a support and a transfer layer containing a light absorbing compound.
• a preferred method comprises the step of contacting the second layer with the transfer layer, preferably while applying heat and/or pressure, thereby carrying over at least part of the transfer layer to form a first layer according to the present invention.
• the method of the latter embodiment can be automated easily, e.g. by incorporating a supply roll of such a transfer material, such as a ribbon impregnated with light absorbing compound, in a print station of a digital press similar to the configuration which is described in EP-A 698 488.
• the transfer material can be unwound from said supply roll and the layer containing the light absorbing compound can then be brought in direct contact with the surface of a plate cylinder or a support mounted on said plate cylinder by one or more contact rollers.
• the used transfer material may be wound up again on a take-up roll.
• the transfer can be carried out so as to obtain a uniform layer which then can be image-wise exposed.
• pressure and/or heat can be applied image-wise during the transfer step, so that the first layer is applied in a patterned form.
• This step then may be followed by intense heating, e.g. by infrared laser exposure.
• intense heating e.g. by infrared laser exposure.
• a suitable printing master may be obtained directly without intense heating.
• the materials of the present invention can be exposed to light by a light emitting diode or a laser such as a He/Ne or Ar laser.
• a laser emitting near infrared light having a wavelength in the range from about 700 to about 1500 nm is used, e.g. a semiconductor laser diode, a Nd:YAG or a Nd:YLF laser.
• the required laser power depends on the pixel dwell time of the laser beam, which is determined by the spot diameter (typical value of modern plate-setters at 1/e 2 of maximum intensity : 10-25 ⁇ m), the scan speed and the resolution of the exposure device (i.e.
• ITD image-setters are typically characterised by a very high scan speed up to 500 m/sec and may require a laser power of several Watts. Satisfactory results have also been obtained by using XTD image-setters having a typical laser power from about 200 mW to about 1 W at a lower scan speed, e.g. from 0.1 to 10 m/sec.
• the non-exposed areas of the first layer can be removed by starting a pressrun, e.g. due to the mechanical friction between the plate and a contacting cylinder or due to dissolution of the first layer in the ink applied onto the plate.
• the non-exposed layer is removed during the first few runs of the printing job.
• the first layer comprises a pigment or dye which absorbs visible light
• its removal may be observed as a fog present in the non-printing areas of the first printed copies.
• the material can also be rubbed before printing, e.g. with a dry cloth, a cotton pad or a rotating brush.
• a non-solvent i.e. a liquid which is not capable of excessively solubilising the second layer
• alcohols such as ethanol, n-propanol, isopropanol or butanol.
• Alkanes such as heptane or iso-octane can also be used with the proviso that their use may not result in an excessive solubilisation of the second layer, which can be prevented by using a highly crosslinked layer, e.g. a cured silicone coating.
• Said optional processing step may be performed on-press, i.e. after mounting the exposed plate on the plate cylinder of a printing press.
• a PET support was coated with a layer comprising poly(vinyl alcohol), hardened with tetramethoxysilane, and titanium dioxide.
• a layer comprising poly(vinyl alcohol), hardened with tetramethoxysilane, and titanium dioxide.
• silicone Dehesive 520 On top of this layer was coated a mixture of 12.5 g of silicone Dehesive 520, 1 g of Vernetzer V03 and 0.5 g of Katalysator C09, all trade names of Wacker-Chemie GmbH (Münich, Germany), to obtain a second layer having a dry thickness of 10 ⁇ m (Example 1).
• Silicone Dehesive 520 has an average molecular weight of about 5000.
• Example 2 the latter coating composition was diluted 4-fold with iso-octane and coated on a similar support as in Example 1, to obtain a second layer having a dry thickness of 2.5 ⁇ m. Both samples were cured at 90 °C during 40 seconds and then rubbed in with a semi-burned cork. The layer thus obtained was tamped with a cotton pad so as to obtain relatively homogenous first layer of soot.
• a test pattern was exposed in heat-mode using an XTD Nd:YAG image-setter (spot-size at 1/e 2 : 23 ⁇ m) at a scan speed of 1 and 2 m/sec and a power of 350, 400 and 450 mW (six different exposures at distinct areas of each sample).
• the image pattern was visible immediately after exposure.
• the samples were then processed by rubbing with a cotton pad that was moistened with water.
• the samples were mounted on an AB Dick 9860 printing press and a pressrun of 100 copies was started using Reflecta Dry Magenta ink, trade name of Hostmann-Steinberg (Celle, Germany), without using a fountain.
• the exposed areas of the samples were ink accepting, indicating that the soot layer was not completely ablated but converted into an ink accepting substance.
• Example 2 50 g of silicone Dehesive 520, 2 g of Vernetzer V03 and 1 g of Katalysator C09, as defined in Example 1, were mixed, coated on a similar support as used in Example 1 to obtain a second layer having a dry thickness of 2 g/m 2 and then cured during 40 seconds at 90°C.
• a first layer of graphite was applied on the above second layer by rubbing in graphite powder consisting of "Graphite Naturel" (particle size ⁇ 20 ⁇ m), trade name of Carbone Lorraine, with a cotton pad.
• “Graphite Artificiel” having a particle size ⁇ 56 ⁇ m was used.
• the samples were exposed with an ITD image-setter, type Crescent 42T of Gerber, USA, at a scan speed of 367 m/sec, a spot size of 24 ⁇ m and a power of 4.25, 5.25 and 6.25 W (three different exposures at distinct areas of each sample). An image was clearly visible immediately after exposure.
• One part of each sample was processed by rubbing with a cotton pad moistened with water (parts 3A and 4A), a second part with a cotton pad moistened with iso-octane (parts 3B and 4B) and a third part was not processed at all (parts 3C and 4C).
• the soot layer was completely removed in parts 3A, 3B, 4A and 4B.
• a pressrun was started on a GTO 52 press, available from Heidelberg, Germany, using Reflecta Dry Magenta ink, defined above, and no fountain. A clear image was printed with parts 3C and 4C.
• Example 5 the same silicone composition as used in Examples 3 and 4 was coated on an aluminium support and the second layer thus obtained was then covered with a soot layer by moving said second layer in the yellow end of a flame fed with butane. This sample was exposed using the same ITD image-setter as in Examples 3 and 4 at a power of 6.25 W.
• a first part of the sample was processed by rubbing with a cotton pad moistened with iso-octane (part 5A), a second part was rubbed with a dry cotton pad (part 5B), a third part was not processed at all (part 5C) and a fourth part was rubbed with a cotton pad moistened with "Rein Trentskonzentrat 1124", trade name of Heidelberg (Germany), and then with a cotton pad moistened with iso-octane (part 5D).
• Parts 5A and 5C provided a suitable printed image.
• Example 5 The same sample as in Example 5 was exposed using an XTD 830 nm laser diode with a scan speed of 3.2 m/sec, a spot size of 11 ⁇ m and a power of 220 and 292 mW (two different exposures at distinct areas of sample 8) or an XTD Nd:YAG image-setter with a scan speed of 3.2 m/sec, a pixel size of 23 ⁇ m and a power of 751 and 1040 mW (also two different exposures at distinct areas of sample 9).
• Each sample was processed in four different ways at distinct parts as given below (all liquids were applied by rubbing with a cotton pad) :
• the same support provided with silicone coating as in Examples 3-4 was rubbed in with a fine powder of the infrared dye having the following formula :
• the dye layer thus obtained was then tamped with a cotton pad.
• the material could be image-wise exposed with an XTD 830 nm laser diode with a scan speed of 3.2 m/sec, a spot size of 11 ⁇ m and a power from 150 to 300 mW as well as with an XTD Nd:YAG image-setter with a scan speed of 3.2 m/sec, a pixel size of 23 ⁇ m and a power of 550 to 975 mW mW.

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• Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Thermal Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Printing Plates And Materials Therefor (AREA)

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• 1999
  • 1999-08-31 EP EP99202797A patent/EP0993945B1/fr not_active Expired - Lifetime

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