EP1025991B1 - Procédé de fabrication de plaques d'impression travaillant en positif - Google Patents

Procédé de fabrication de plaques d'impression travaillant en positif Download PDF

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Publication number
EP1025991B1
EP1025991B1 EP19990200291 EP99200291A EP1025991B1 EP 1025991 B1 EP1025991 B1 EP 1025991B1 EP 19990200291 EP19990200291 EP 19990200291 EP 99200291 A EP99200291 A EP 99200291A EP 1025991 B1 EP1025991 B1 EP 1025991B1
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EP
European Patent Office
Prior art keywords
layer
imaging element
surfactant
lithographic
top layer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP19990200291
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German (de)
English (en)
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EP1025991A1 (fr
Inventor
Joan Vermeersch
Marc Van Damme
Dirk Kokkelenberg
Bart Braspenninckx
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Agfa Gevaert NV
Original Assignee
Agfa Gevaert NV
Agfa Gevaert AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Agfa Gevaert NV, Agfa Gevaert AG filed Critical Agfa Gevaert NV
Priority to DE1999609733 priority Critical patent/DE69909733T2/de
Priority to EP19990200291 priority patent/EP1025991B1/fr
Priority to US09/476,109 priority patent/US6458510B1/en
Priority to JP2000021300A priority patent/JP2000221670A/ja
Publication of EP1025991A1 publication Critical patent/EP1025991A1/fr
Application granted granted Critical
Publication of EP1025991B1 publication Critical patent/EP1025991B1/fr
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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
    • 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
    • B41N3/06—Preparing for use and conserving printing surfaces by use of detergents
    • 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
    • B41C2210/02—Positive working, i.e. the exposed (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
    • B41C2210/04—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
    • B41C2210/06—Developable by an alkaline 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
    • B41C2210/14—Multiple imaging layers
    • 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
    • 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
    • B41C2210/26—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 not involving carbon-to-carbon unsaturated bonds
    • B41C2210/262—Phenolic condensation polymers, e.g. novolacs, resols

Definitions

  • the present invention relates to a method for preparing a lithographic printing plate. More specifically the invention is related to a method for preparing a lithographic printing plate with improved printing properties.
  • Lithography is the process of printing from specially prepared surfaces, some areas of which are capable of accepting lithographic ink, whereas other areas, when moistened with water, will not accept the ink.
  • the areas which accept ink form the printing image areas and the ink-rejecting areas form the background areas.
  • a photographic material is made imagewise receptive to oily or greasy inks in the photo-exposed (negative-working) or in the non-exposed areas (positive-working) on a hydrophilic background.
  • lithographic printing plates also called surface litho plates or planographic printing plates
  • a support that has affinity to water or obtains such affinity by chemical treatment is coated with a thin layer of a photosensitive composition.
  • Coatings for that purpose include light-sensitive polymer layers containing diazo compounds, dichromate-sensitized hydrophilic colloids and a large variety of synthetic photopolymers. Particularly diazo-sensitized systems are widely used.
  • the exposed image areas become insoluble and the unexposed areas remain soluble.
  • the plate is then developed with a suitable liquid to remove the diazonium salt or diazo resin in the unexposed areas.
  • printing plates are known that include a photosensitive coating that upon image-wise exposure is rendered soluble at the exposed areas. Subsequent development then removes the exposed areas.
  • a typical example of such photosensitive coating is a quinone-diazide based coating.
  • the above described photographic materials from which the printing plates are made are camera-exposed through a photographic film that contains the image that is to be reproduced in a lithographic printing process.
  • Such method of working is cumbersome and labor intensive.
  • the printing plates thus obtained are of superior lithographic quality.
  • GB-1 492 070 discloses a method wherein a metal layer or a layer containing carbon black is provided on a photosensitive coating. This metal layer is then ablated by means of a laser so that an image mask on the photosensitive layer is obtained. The photosensitive layer is then overall exposed by UV-light through the image mask. After removal of the image mask, the photosensitive layer is developed to obtain a printing plate.
  • This method however still has the disadvantage that the image mask has to be removed prior to development of the photosensitive layer by a cumbersome processing.
  • thermoplastic polymer particles By image-wise exposure to an infrared laser, the thermoplastic polymer particles are image-wise coagulated thereby rendering the surface of the imaging element at these areas ink-acceptant without any further development.
  • a disadvantage of this method is that the printing plate obtained is easily damaged since the non-printing areas may become ink accepting when some pressure is applied thereto. Moreover, under critical conditions, the lithographic performance of such a printing plate may be poor and accordingly such printing plate has little lithographic printing latitude.
  • US-P- 4 708 925 discloses imaging elements including a photosensitive composition comprising an alkali-soluble novolac resin and an onium-salt. This composition may optionally contain an IR-sensitizer. After image-wise exposing said imaging element to UV - visible - or IR-radiation followed by a development step with an aqueous alkali liquid there is obtained a positive or negative working printing plate. The printing results of a lithographic plate obtained by irradiating and developing said imaging element are poor. No washing step is mentioned.
  • EP-A- 625 728 discloses an imaging element comprising a layer which is sensitive to UV- and IR-irradiation and which may be positive or negative working.
  • This layer comprises a resole resin, a novolac resin, a latent Bronsted acid and an IR-absorbing substance.
  • the printing results of a lithographic plate obtained by irradiating and developing said imaging element are poor. No washing step is mentioned.
  • US-P- 5 340 699 is almost identical with EP-A- 625 728 but discloses the method for obtaining a negative working IR-laser recording imaging element.
  • the IR-sensitive layer comprises a resole resin, a novolac resin, a latent Bronsted acid and an IR-absorbing substance.
  • the printing results of a lithographic plate obtained by irradiating and developing said imaging element are poor. No washing step is mentioned
  • EP-A- 678 380 discloses a method wherein a protective layer is provided on a grained metal support underlying a laser-ablatable surface layer. Upon image-wise exposure the surface layer is fully ablated as well as some parts of the protective layer. The printing plate is then treated with a cleaning solution to remove the residu of the protective layer and thereby exposing the hydrophilic surface layer. No washing step is mentioned.
  • EP-A- 0 908 306 and EP-A- 0 908 304 (both belonging to the prior art according to Art. 54(3) EPC) disclose a heat mode imaging element consisting of a lithographic base with a hydrophilic surface and a top layer which top layer is sensitive to IR-radiation, comprises a polymer, soluble in an aqueous alkaline solution and is unpenetratable for an alkaline developer containing SiO 2 as silicates.
  • EP-A- 0 950 518 and EP-A- 0 950 517 (both belonging to the prior art according to Art. 54(3) EPC) discloses that the difference in solubility with said plates is increased by use of siloxane surfactants.
  • the plate is rinsed with water and then treated with a gumming solution in order to protect the grained and anodized aluminum surface against chemical (oxidation) and mechanical (scratches) failures.
  • a brush or a surfactant in the washing solution is mentioned.
  • a plate is treated with a baking gum and a baking step (a static treatment during 5 minutes at 235°C or a dynamic treatment during 2 minutes at 270°C), thereby crosslinking the image areas and improving the adhesion of the image areas to the grained and anodized aluminum surface.
  • a baking gum and a baking step a static treatment during 5 minutes at 235°C or a dynamic treatment during 2 minutes at 270°C
  • the rinsing of the developed imaging element is carried out with a brush preferably during at least 2 s, more preferably during at least 5 s at a temperature of preferably at least 15°C, more preferably at least 20°C.
  • the rinsing is carried out with an aqueous solution containing a surfactant.
  • Said surfactant can be a cationic, an anionic, an amphoteric or a non-ionic surfactant.
  • the surfactant is a non-ionic surfactant or a perfluoroalkyl surfactant.
  • the surface tension of said aqueous solution is preferably less than 40mN/m, more preferably less than 30 mN/m.
  • the contact time between the aqueous solution containing a surfactant and the developed imaging element is preferably at least 10 s, more preferably at lease 20 s.
  • Baking gum solution or baking gumming solutions can be aqueous solutions of sodium dodecyl phenoxy benzene disulphonate, alkylated naphthalene sulphonic acid, sulphonated alkyl diphenyl oxide, methylene dinaphthalene sulphonic acid, etc.
  • Other gumming solutions contain a hydrophilic polymer component and an organic acid component.
  • Still other baking gumming solutions contains the potassium salt of the hydroxyethylidene diphosphonic acid.
  • Still other baking gumming solutions contain a sulphosuccinamate compound and phosphoric acid. Said acids or salts are preferably present in the aqueous gumming solution in a concentration of 1 to 20 weight %, more preferably 2 to 10 weight %.
  • the top layer of the imaging element is also called the second layer
  • the first layer and the top layer are different.
  • a heat mode imaging element for making lithographic printing plates having on a lithographic base with a hydrophilic surface a first layer including a polymer, soluble in an aqueous alkaline solution and a top layer on the same side of the lithographic base as the first layer which top layer is sensitive to IR-radiation and which is unpenetratable for an alkaline developer.
  • the top layer in accordance with the present invention comprises an IR-dye or pigment and a binder resin.
  • a mixture of IR-dyes or pigments may be used, but it is preferred to use only one IR-dye or pigment.
  • Preferably said IR-dyes are IR-cyanines dyes.
  • Particularly useful IR-cyanine dyes are cyanines dyes with two indolenine groups.
  • IR-absorbing pigments are 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. WO2.9. It is also possible to use conductive polymer dispersion such as polypyrrole or polyaniline-based conductive polymer dispersions. The lithographic performance and in particular the print endurance obtained depends on the heat-sensitivity of the imaging element. In this respect it has been found that carbon black yields very good and favorable results.
  • the IR-absorbing dyes or pigments are present preferably in an amount between 1 and 99 parts, more preferably between 50 and 95 parts by weight of the total amount of said IR-sensitive top layer.
  • the top layer may preferably comprise as binder a water insoluble polymer such as a cellulose ester, a copolymer of vinylidene chloride and acrylonitrile, poly(meth)acrylates, polyvinyl chloride, silicone resins, etc.
  • binder is nitrocellulose resin.
  • the total amount of the top layer preferably ranges from 0.03 to 10 g/m 2 , more preferably from 0.05 to 2 g/m 2 .
  • top layer a difference in the capacity of being penetrated and/or solubilised by the aqueous alkaline solution is generated upon image-wise exposure for an alkaline developer according to the invention.
  • the said capacity is increased upon image-wise IR exposure to such degree that the imaged parts will be cleaned out during development without solubilising and/or damaging the non-imaged parts.
  • the development with the aqueous alkaline solution is preferably done within an interval of 5 to 120 seconds.
  • the present invention comprises a first layer soluble in an aqueous alkaline developing solution with preferentially a pH between 7.5 and 14.
  • Said layer is preferably contiguous to the top layer but other layers may be present between the top layer and the first layer.
  • the alkali soluble binders used in this layer are preferably hydrophobic binders as used in conventional positive or negative working PS-plates e.g. novolac polymers, polymers containing hydroxystyrene units, carboxy substituted polymers etc. Typical examples of these polymers are descibed in DE-A- 4 007 428, DE-A- 4 027 301 and DE-A- 4 445 820.
  • the hydrophobic binder used in connection with the present invention is further characterised by insolubility in water and partial solubility/swellability in an alkaline solution and/or partial solubility in water when combined with a cosolvent.
  • this aqueous alkali soluble layer is preferably a visible light- and UV-light desensitised layer. Said layer is preferably thermally hardenable.
  • This preferably visible light- and UV-desensitised layer does not comprise photosensitive ingredients such as diazo compounds, photoacids, photoinitiators, quinone diazides, sensitisers etc. which absorb in the wavelength range of 250nm to 650nm. In this way a daylight stable printing plate may be obtained.
  • Said first layer preferably also includes a low molecular acid, preferably a carboxylic acid, still more preferably a benzoic acid, most preferably 3,4,5-trimethoxybenzoic acid or a benzophenone.
  • a low molecular acid preferably a carboxylic acid, still more preferably a benzoic acid, most preferably 3,4,5-trimethoxybenzoic acid or a benzophenone.
  • the ratio between the total amount of low molecular acid or benzophenone and polymer in the first layer preferably ranges from 2:98 to 40:60, more preferably from 5:95 to 20:80.
  • the total amount of said first layer preferably ranges from 0.1 to 10 g/m 2 , more preferably from 0.3 to 2 g/m 2 .
  • the first layer and/or the top (also called the second) layer comprises a siloxane surfactant.
  • Other surfactants can be present.
  • Said surfactants can be cationic, anionic or amphoteric surfactants, but are more preferably non-ionic surfactants.
  • the surfactant is most preferably selected from the group consisting of perfluoroalkyl surfactants and alkylphenyl surfactants.
  • the surfactant is preferably present in the top layer.
  • the amount of surfactant lies preferably in the range from 0.001 to 0.3g/m 2 , more preferably in the range from 0.003 to 0.050g/m 2 .
  • the lithographic base may be an anodised aluminum for all embodiments.
  • a particularly preferred lithographic base is an electrochemically grained and anodised aluminum support.
  • the anodised aluminum support may be treated to improve the hydrophilic properties of its surface.
  • the aluminum support may be silicated by treating its surface with sodium silicate solution at elevated temperature, e.g. 95°C.
  • a phosphate treatment may be applied which involves treating the aluminum oxide surface with a phosphate solution that may further contain an inorganic fluoride.
  • the aluminum oxide surface may be rinsed with a citric acid or citrate solution.
  • This treatment may be carried out at room temperature or may be carried out at a slightly elevated temperature of about 30 to 50°C.
  • a further interesting treatment involves rinsing the aluminum oxide surface with a bicarbonate solution. Still further, the aluminum oxide surface may be treated with polyvinylphosphonic acid, polyvinylmethylphosphonic acid, phosphoric acid esters of polyvinyl alcohol, polyvinylsulphonic acid, polyvinylbenzenesulphonic acid, sulphuric acid esters of polyvinyl alcohol, and acetals of polyvinyl alcohols formed by reaction with a sulphonated aliphatic aldehyde It is further evident that one or more of these post treatments may be carried out alone or in combination.
  • the lithographic base having a hydrophilic surface comprises a flexible support, such as e.g. paper or plastic film, provided with a cross-linked hydrophilic layer for all embodiments.
  • a particularly suitable cross-linked hydrophilic layer may be obtained from a hydrophilic binder cross-linked with a cross-linking agent such as formaldehyde, glyoxal, polyisocyanate or a hydrolysed tetra-alkylorthosilicate. The latter is particularly preferred.
  • hydrophilic binder there may be used hydrophilic (co)polymers or mixtures thereof such as for example, gelatin, polyvinyl pyrrolidone, starch or modified starch, xanthane gum, carboxymethyl cellulose or modified carboxymethyl cellulose, homopolymers and copolymers of vinyl alcohol, acrylamide, methylol acrylamide, methylol methacrylamide, acrylate acid, methacrylate acid, hydroxyethyl acrylate, hydroxyethyl methacrylate or maleic anhydride/vinylmethylether copolymers.
  • hydrophilic (co)polymers or mixtures thereof such as for example, gelatin, polyvinyl pyrrolidone, starch or modified starch, xanthane gum, carboxymethyl cellulose or modified carboxymethyl cellulose, homopolymers and copolymers of vinyl alcohol, acrylamide, methylol acrylamide, methylol methacrylamide, acrylate acid, methacrylate
  • the hydrophilicity of the (co)polymer or (co)polymer mixture used is preferably the same as or higher than the hydrophilicity of polyvinyl acetate hydrolyzed to at least an extent of 60 percent by weight, preferably 80 percent by weight.
  • the amount of crosslinking agent, in particular of tetraalkyl orthosilicate, is preferably at least 0.2 parts by weight per part by weight of hydrophilic binder, more preferably between 0.5 and 5 parts by weight, most preferably between 1.0 parts by weight and 3 parts by weight.
  • a cross-linked hydrophilic layer in a lithographic base used in accordance with the present embodiment preferably also contains substances that increase the mechanical strength and the porosity of the layer.
  • colloidal silica may be used.
  • the colloidal silica employed may be in the form of any commercially available water-dispersion of colloidal silica for example having an average particle size up to 40 nm, e.g. 20 nm.
  • inert particles of larger size than the colloidal silica may be added e.g. silica prepared according to Stöber as described in J. Colloid and Interface Sci., Vol.
  • alumina particles or particles having an average diameter of at least 100 nm which are particles of titanium dioxide or other heavy metal oxides.
  • the thickness of a cross-linked hydrophilic layer in a lithographic base in accordance with this embodiment may vary in the range of 0.2 to 25 ⁇ m and is preferably 1 to 10 ⁇ m.
  • plastic film e.g. substrated polyethylene terephthalate film, substrated polyethylene naphthalate film, cellulose acetate film, polystyrene film, polycarbonate film etc.
  • the plastic film support may be opaque or transparent.
  • the amount of silica in the adhesion improving layer is between 200 mg per m 2 and 750 mg per m 2 .
  • the ratio of silica to hydrophilic binder is preferably more than 1 and the surface area of the colloidal silica is preferably at least 300 m 2 per gram, more preferably at least 500 m 2 per gram.
  • a heat mode imaging element for making lithographic printing plates having on a lithographic base with a hydrophilic surface a top layer which top layer is sensitive to IR-radiation comprises a polymer, soluble in an aqueous alkaline solution and is unpenetratable for or insoluble in an alkaline developer.
  • the IR-sensitive layer in accordance with the present invention comprises an IR-dye or pigment and a polymer, soluble in an aqueous alkaline solution.
  • a mixture of IR-dyes or pigments may be used, but it is preferred to use only one IR-dye or pigment. Suitable IR-dyes and pigments are those mentioned above in the first embodiment of the present invention.
  • the IR-dyes or pigments are present preferably in an amount between 1 and 60 parts, more preferably between 3 and 50 parts by weight of the total amount of said IR-sensitive top layer.
  • the alkali soluble polymers used in this layer are preferably hydrophobic and ink accepting polymers as used in conventional positive or negative working PS-plates e.g. carboxy substituted polymers etc. More preferably is a phenolic resin such as a hydroxystyrene units containing polymer or a novolac polymer. Most preferred is a novolac polymer. Typical examples of these polymers are descibed in DE-A- 4 007 428 , DE-A- 4 027 301 and DE-A- 4 445 820 .
  • the hydrophobic polymer used in connection with the present invention is further characterised by insolubility in water and at least partial solubility/swellability in an alkaline solution and/or at least partial solubility in water when combined with a cosolvent.
  • this IR-sensitive layer is preferably a visible light- and UV-light desensitised layer. Still further said layer is preferably thermally hardenable.
  • This preferably visible light- and UV-light desensitised layer does not comprise photosensitive ingredients such as diazo compounds, photoacids, photoinitiators, quinone diazides, sensitisers etc. which absorb in the wavelength range of 250nm to 650nm. In this way a daylight stable printing plate may be obtained.
  • Said IR-sensitive layer preferably also includes a low molecular acid, more preferably a carboxylic acid, still more preferably a benzoic acid, most preferably 3,4,5-trimethoxybenzoic acid or a benzophenone, more preferably trihydroxybenzophenone.
  • a low molecular acid more preferably a carboxylic acid, still more preferably a benzoic acid, most preferably 3,4,5-trimethoxybenzoic acid or a benzophenone, more preferably trihydroxybenzophenone.
  • the ratio between the total amount of low molecular acid or benzophenone and polymer in the IR-sensitive layer preferably ranges from 2:98 to 40:60, more preferably from 5:95 to 30:70.
  • the total amount of said IR-sensitive layer preferably ranges from 0.01 to 10 g/m 2 , more preferably from 0.03 to 2 g/m 2 .
  • the top layer comprises a siloxane surfactant.
  • Another surfactant can also be present.
  • Said surfactant can be a cationic, an anionic or an amphoteric surfactant, but is more preferably a non-ionic surfactant.
  • the surfactant is most preferably selected from the group consisting of perfluoroalkyl surfactants and alkylphenyl surfactants.
  • the amount of surfactant lies preferably in the range from 0.001 to 0.3g/m 2, more preferably in the range from 0.003 to 0.050g/m 2 .
  • a difference in the capacity of being penetrated and/or solubilised by the alkaline developer is generated upon image-wise exposure for an alkaline developer according to the invention.
  • the heat-mode imaging element is image-wise exposed and developed.
  • Image-wise exposure in connection with the present invention is an image-wise scanning exposure involving the use of a laser that operates in the infrared or near-infrared, i.e. wavelength range of 700-1500 nm. Most preferred are laser diodes emitting in the near-infrared. Exposure of the imaging element may be performed with lasers with a short as well as with lasers with a long pixel dwell time. Preferred are lasers with a pixel dwell time between 0.005 ⁇ s and 20 ⁇ s.
  • the heat mode imaging element is developed by rinsing it with an aqueous alkaline solution.
  • aqueous alkaline solutions used in the present invention are those that are used for developing conventional positive working presensitised printing plates, preferably containing SiO 2 as silicates and having preferably a pH between 11.5 and 14.
  • the imaged parts of the top layer that were rendered more penetrable for the aqueous alkaline solution upon exposure are cleaned-out whereby a positive working printing plate is obtained.
  • the composition of the developer used is also very important.
  • the developers and replenishers for developer used in the invention are preferably aqueous solutions mainly composed of alkali metal silicates and alkali metal hydroxides represented by MOH or their oxyde, represented by M 2 O, wherein said developer comprises SiO 2 and M 2 O in a molar ratio of 0.5 to 1.5 and a concentration of SiO 2 of 0.5 to 5% by weight.
  • alkali metal silicates preferably used are, for instance, sodium silicate, potassium silicate, lithium silicate and sodium metasilicate.
  • alkali metal hydroxides preferred are sodium hydroxide, potassium hydroxide and lithium hydroxide.
  • the developers used in the invention may simultaneously contain other alkaline agents.
  • other alkaline agents include such inorganic alkaline agents as ammonium hydroxide, sodium tertiary phosphate, sodium secondary phosphate, potassium tertiary phosphate, potassium secondary phosphate, ammonium tertiary phosphate, ammonium secondary phosphate, sodium bicarbonate, sodium carbonate, potassium carbonate and ammonium carbonate; and such organic alkaline agents as mono-, di- or triethanolamine, mono-, dior trimethylamine, mono-, di- or triethylamine, mono- or diisopropylamine, n-butylamine, mono-, di- or triisopropanolamine, ethyleneimine, ethylenediimine and tetramethylammonium hydroxide.
  • the concentration of SiO 2 in the developer and replenisher preferably ranges from 1 to 4 % by weight. Such limitation of the concentration of SiO 2 makes it possible to stably provide lithographic printing plates having good finishing qualities even when a large amount of plates according to the invention are processed for a long time period.
  • an aqueous solution of an alkali metal silicate having a molar ratio [SiO 2 ] / [M 2 O], which ranges from 1.0 to 1.5 and a concentration of SiO 2 of 1 to 4 % by weight is used as a developer.
  • a replenisher having alkali strength equal to or more than that of the developer is employed.
  • a molar ratio, [SiO 2 ] / [M 2 O] of the replenisher is equal to or smaller than that of the developer, or that a concentration of SiO 2 is high if the molar ratio of the developer is equal to that of the replenisher.
  • organic solvents having solubility in water at 20 °C of not more than 10 % by weight according to need.
  • organic solvents are such carboxylic acid esters as ethyl acetate, propyl acetate, butyl acetate, amyl acetate, benzyl acetate, ethylene glycol monobutyl acetate, butyl lactate and butyl levulinate; such ketones as ethyl butyl ketone, methyl isobutyl ketone and cyclohexanone; such alcohols as ethylene glycol monobutyl ether, ethylene glycol benzyl ether, ethylene glycol monophenyl ether, benzyl alcohol, methylphenylcarbinol, n-amyl alcohol and methylamyl alcohol; such alkyl-substituted aromatic hydrocarbons as xylene; and such halogenated hydrocarbons
  • organic solvents may be used alone or in combination. Particularly preferred is benzyl alcohol in the invention. These organic solvents are added to the developer or replenisher therefor generally in an amount of not more than 5 % by weight and preferably not more than 4 % by weight.
  • the developers and replenishers used in the present invention may simultaneously contain a surfactant for the purpose of improving developing properties thereof.
  • surfactants include salts of higher alcohol (C 8 ⁇ C 22 ) sulfuric acid esters such as sodium salt of lauryl alcohol sulfate, sodium salt of octyl alcohol sulfate, ammonium salt of lauryl alcohol sulfate, Teepol B-81 (trade mark, available from Shell Chemicals Co., Ltd.) and disodium alkyl sulfates; salts of aliphatic alcohol phosphoric acid esters such as sodium salt of cetyl alcohol phosphate; alkyl aryl sulfonic acid salts such as sodium salt of dodecylbenzene sulfonate, sodium salt of isopropylnaphthalene sulfonate,sodium salt of dinaphthalene disulfonate and sodium salt of metanitrobenzene sulfonate; sulfonic acid salts of alky
  • Examples of such compounds are neutral salts such as NaCl, KCl and KBr as disclosed in JN-A- 58- 75 152 ; chelating agents such as EDTA and NTA as disclosed in JN-A- 58- 190 952 (U.S-A- 4 469 776), complexes such as [Co(NH 3 ) 6 ]Cl 3 as disclosed in JN-A- 59- 121 336 (US-A- 4 606 995); ionizable compounds of elements of the group IIa, IIIa or IIIb of the Periodic Table such as those disclosed in JN-A- 55- 25 100; anionic or amphoteric surfactants such as sodium alkyl naphthalene sulfonate and N-tetradecyl-N,N-dihydroxythyl betaine as disclosed in JN-A- 50- 51 324; tetramethyldecyne, diol as disclosed in US-A- 4 374 920; non-i
  • any known means of supplementing a replenisher for developer may be employed.
  • Examples of such methods preferably used are a method for intermittently or continuously supplementing a replenisher as a function of the amount of PS plates processed and time as disclosed in JN-A- 55- 115 039 (GB-A- 2 046 931) , a method comprising disposing a sensor for detecting the degree of light-sensitive layer dissolved out in the middle portion of a developing zone and supplementing the replenisher in proportion to the detected degree of the light-sensitive layer dissolved out as disclosed in JN-A- 58- 95 349 (US-A- 4 537 496) ; a method comprising determining the impedance value of a developer and processing the detected impedance value by a computer to perform supplementation of a replenisher as disclosed in GB-A- 2 208 249 .
  • the plate is then preferably rinsed with water and treated with a baking gum solution.
  • said plate is baked at a temperature above 50°C, preferably above 100°C, more preferably between 200°C and 300°C for a period of at least 30 seconds, more preferably for a period between 1 and 10 minutes.
  • a 0.30 mm thick aluminum foil was degreased by immersing the foil in an aqueous solution containing 5 g/l of sodium hydroxide at 50°C and rinsed with demineralized 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 aluminum 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 aluminum foil was then etched with an aqueous solution containing 300 g/l of sulfuric acid at 60°C for 180 seconds and rinsed with demineralized water at 25°C for 30 seconds.
  • the foil was subsequently subjected to anodic oxidation in an aqueous solution containing 200 g/l of sulfuric acid at a temperature of 45°C, a voltage of about 10 V and a current density of 150 A/m 2 for about 300 seconds to form an anodic oxidation film of 3.00 g/m 2 of Al 2 O 3 then washed with demineralized water, posttreated with a solution containing polyvinylphosphonic acid and subsequently with a solution containing aluminum trichloride, rinsed with demineralized water at 20°C during 120 seconds and dried.
  • lithographic base On the above described lithographic base was first coated a layer from a 8.6% wt solution in tetrahydrofuran/methoxypropanol 55/45 ratio, with a wet coating thickness of 14 ⁇ m.
  • the resulting layer contained 80% of ALNOVOL SPN452 TM (sold by Clariant, Germany) and 20% of 3,4,5-trimethoxybenzoic acid.
  • ALNOVOL SPN452 TM sold by Clariant, Germany
  • 34,5-trimethoxybenzoic acid Upon this layer was coated with a wet coating thickness of 20 ⁇ m, the IR-sensitive layer from a 0.31% wt solution in methylethylketone/methoxypropanol 50/50 ratio. This layer was dried at a temperature of at least 120°C for at least 80 seconds.
  • the resulting IR-sensitive layer contained 30 mg/m 2 of IR-absorber I, 17.5 mg/m 2 of FLEXO-BLAU 630 TM, 2.0 mg/m 2 of TEGO WET 265 TM and 5.0 mg/m 2 of TEGO GLIDE 410 TM (both siloxanes surfactants from Goldschmitt, Germany).
  • FLEXO-BLAU 630 is commercially available by BASF, Ludwigshafen, Germany.
  • the material was imaged with a Creo 3244 Trendsetter TM external drum platesetter at 130 mJ/cm 2 and 2400 dpi.
  • the exposed material was developed in a Autolith PN 85CE TM processor filled with an aqueous alkaline positive developer EP 26 TM (commercially available from Agfa) in the developer section, filled with water in the rinsing section and processing with a molton brush in the rinsing section, and treated with Ozasol RC 515 TM(commercially available from Agfa)baking gum solution in the gumming section. Processing speed was 0.96 m/min and developer temperature was 25°C. After processing the obtained plate was post-baked for 2 min at 270°C to guarantee high run length.
  • EP 26 TM commercially available from Agfa
  • the exposed material was developed in a Technigraph NPX32TM processor (having no brush i.e. no mechanical treatment in the rinsing section) filled with an aqueous alkaline EP 26TM positive developer in the developer section , filled with water in the rinsing section and equipped with Ozasol RC 515TM baking gum in the gumming section. Processing speed was 1 m/min and developer temperature was 25°C. After processing the exposed imaging element was baked for 5 min at 230°C to guarantee high run length. Printing this material was carried out on a GTO 52 press TM equipped with a Dahlgren dampening system TM , with Rotamatic fountain solution TM and K+E Skinnex Magenta Ink TM.
  • both plates showed an even spreading and covering of baking gum on the image parts, and no problems of uneven ink-uptake, i.e. uncontrolled ink splitting from the plate surface, were found.

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Thermal Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Photosensitive Polymer And Photoresist Processing (AREA)
  • Materials For Photolithography (AREA)
  • Manufacture Or Reproduction Of Printing Formes (AREA)

Claims (10)

  1. Procédé pour la préparation d'un cliché d'impression lithographique, comprenant les étapes consistant à :
    exposer à de la lumière infrarouge, un élément de formation d'image comprenant, sur une base lithographique munie d'une surface hydrophile, une première couche englobant un polymère soluble dans une solution alcaline aqueuse et une couche de protection du même côté de la base lithographique que celui concerné par la première couche, ladite couche de protection étant sensible au rayonnement infrarouge et impénétrable pour un révélateur alcalin ou étant insoluble dans ce dernier, dans lequel ladite première couche et ladite couche de protection peuvent représenter une seule et même couche, ledit élément de formation d'image comprenant un agent tensioactif à base de siloxane ;
    développer ledit élément de formation d'image exposé avec une solution alcaline ;
    rincer ledit élément de formation d'image développé avec de l'eau ou avec une solution aqueuse ;
    gommer ledit élément de formation d'image développé avec une solution de gomme de cuisson ;
    soumettre ledit élément de formation d'image sousmis à un gommage à un traitement thermique à une température supérieure à 50 °C ;
    caractérisé en ce qu'on effectue ledit rinçage à la brosse et/ou avec de l'eau contenant un agent tensioactif.
  2. Procédé selon la revendication 1, dans lequel ladite eau contenant un agent tensioactif possède une tension superficielle inférieure à 40 mN/m.
  3. Procédé selon la revendication 1 ou 2, dans lequel ladite eau contenant un agent tensioactif possède une tension superficielle inférieure à 30 mN/m.
  4. Procédé selon l'une quelconque des revendications 1 à 3, dans lequel ledit agent tensioactif est un agent tensioactif non ionique.
  5. Procédé selon l'une quelconque des revendications 1 à 3, dans lequel ledit agent tensioactif est un composé de perfluoroalkyle.
  6. Procédé selon la revendication 1, dans lequel ladite brosse est une brosse rotative.
  7. Procédé selon l'une quelconque des revendications 1 à 6, dans lequel ledit élément de formation d'image comprend au moins une couche soluble dans les alcalis contenant de la novolaque.
  8. Procédé selon l'une quelconque des revendications 1 à 7, dans lequel la base lithographique est un support en aluminium soumis à un grainage électrochimique et à une anodisation.
  9. Procédé selon l'une quelconque des revendications 1 à 8, dans lequel le développement avec une solution alcaline dissout les zones exposées et n'affecte pas les zones non exposées.
  10. Procédé selon l'une quelconque des revendications 1 à 9, dans lequel ladite solution alcaline contient un silicate de métal alcalin.
EP19990200291 1999-02-02 1999-02-02 Procédé de fabrication de plaques d'impression travaillant en positif Expired - Lifetime EP1025991B1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
DE1999609733 DE69909733T2 (de) 1999-02-02 1999-02-02 Verfahren zur Herstellung positiv arbeitender Druckplatten
EP19990200291 EP1025991B1 (fr) 1999-02-02 1999-02-02 Procédé de fabrication de plaques d'impression travaillant en positif
US09/476,109 US6458510B1 (en) 1999-02-02 2000-01-03 Method for making positive working printing plates
JP2000021300A JP2000221670A (ja) 1999-02-02 2000-01-31 ポジティブ作用性印刷版の作製法

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EP1025991B1 true EP1025991B1 (fr) 2003-07-23

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US6613494B2 (en) * 2001-03-13 2003-09-02 Kodak Polychrome Graphics Llc Imageable element having a protective overlayer
US7316891B2 (en) 2002-03-06 2008-01-08 Agfa Graphics Nv Method of developing a heat-sensitive lithographic printing plate precursor with a gum solution
EP1586448B1 (fr) * 2002-03-06 2007-12-12 Agfa Graphics N.V. Procédé de développement d'un précurseur thermosensible pour une plaque lithographique avec une solution de gomme
ITVA20020029A1 (it) 2002-03-22 2003-09-22 Lamberti Spa Composizioni per lastre litografiche positive termiche
US7767382B2 (en) 2004-05-19 2010-08-03 Agfa Graphics Nv Method of making a photopolymer printing plate
JP2009507680A (ja) 2005-09-09 2009-02-26 プレステク，インコーポレイテッド 浸透性変化層を有する印刷部材及び関連する方法
JP5319097B2 (ja) 2007-10-16 2013-10-16 イーストマン コダック カンパニー ポジ型平版印刷版原版及びその製版方法
WO2016060137A1 (fr) * 2014-10-14 2016-04-21 太陽インキ製造株式会社 Structure stratifiée

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JPS55115045A (en) * 1979-02-27 1980-09-04 Fuji Photo Film Co Ltd Printing plate preparation
JPS6223045A (ja) * 1985-07-22 1987-01-31 Konishiroku Photo Ind Co Ltd 感光性平版印刷版の処理方法
JPS6323160A (ja) * 1986-07-16 1988-01-30 Konica Corp 安定性、均一性等が改良される感光性平版印刷版の現像処理方法
JPH02209294A (ja) * 1989-02-10 1990-08-20 Dainippon Ink & Chem Inc 平版印刷用湿し水濃厚液
JPH06206391A (ja) * 1990-12-11 1994-07-26 Nikken Kagaku Kenkyusho:Kk 平版印刷版の湿し水用添加剤及び湿し水原液
JPH09146268A (ja) * 1995-11-21 1997-06-06 Konica Corp 感光性組成物及び感光性平版印刷版
DE69833046T2 (de) * 1997-03-11 2006-08-03 Agfa-Gevaert Verfahren zur Herstellung einer lithographischen Druckplatte

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DE69909733D1 (de) 2003-08-28
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JP2000221670A (ja) 2000-08-11

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