Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
  • B41M5/36—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using a polymeric layer, which may be particulate and which is deformed or structurally changed with modification of its' properties, e.g. of its' optical hydrophobic-hydrophilic, solubility or permeability properties
  • B41M5/368—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using a polymeric layer, which may be particulate and which is deformed or structurally changed with modification of its' properties, e.g. of its' optical hydrophobic-hydrophilic, solubility or permeability properties involving the creation of a soluble/insoluble or hydrophilic/hydrophobic permeability pattern; Peel development
• • 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
  • 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
  • B41N1/00—Printing plates or foils; Materials therefor
  • B41N1/006—Printing plates or foils; Materials therefor made entirely of inorganic materials other than natural stone or metals, e.g. ceramics, carbide materials, ferroelectric materials

Definitions

• This invention relates to lithographic p ⁇ nting plates and their process of use More particularly, this invention relates to lithographic printing plates which can be digitally imaged by infrared laser light
• Conventional lithographic printing plates typically have a radiation sensitive, oleophilic image layer coated over a hydrophilic underlay er
• the plates are imaged by imagewise exposure to actinic radiation to produce imaged areas which are either soluble (positive working) or insoluble (negative working) in a developer liquid
• the soluble areas are removed by the developer liquid from underlying hydrophilic surface areas to produce a finished plate with mk receptive oleophilic image areas separated by complimentary, fountain solution receptive hydrophilic areas
• a fountain solution is applied to the imaged plate to wet the hydrophilic areas, so as to insure that only the oleophilic image areas will pick up ink for deposition on the paper stock as a p ⁇ nted image
• Conventional lithographic printing plates typically have been imaged using ultraviolet radiation transmitted imagewise through a suitable htho film in contact with the surface of the p ⁇ nting plate
• the radiation sensitive layer typically contains a dye or pigment which absorbs the incident infrared radiation and the absorbed energy initiates the thermal reaction to produce the image
• each of these thermal imaging systems requires either a pre- or post- baking step to complete image formation , or blanket pre exposure to ultraviolet radiation to activate the layer.
• Each of the disclosed radiation sensitive lithographic pnnting plates requires a development step typically with a highly alkaline developer which is prone to reaction with atmospheric carbon dioxide after non p ⁇ nting areas are removed the developed plate typically requires nnsing and drying pnor to mounting on the printing press
• nnsing and drying pnor to mounting on the printing press
• porous hydrophilic layer applied to the sheet substrate, wherein the porous hydrophilic layer consists of aluminosilicate, and
• an imaging laver applied to the riydrophihc layer, wherein the imaging layer is porous and comprises a thermally reactive composition
• a further embodiment of this invention is a lithographic p ⁇ nting plate comp ⁇ sing (a) a sheet substrate,
• porous hydrophilic layer applied to the sheet substrate, wherein the porous hvdrophilic layer consists essentially of aluminosilicate, and
• an imagmg layer applied to the hydrophilic layer wherein the imaging layer consists essentially of (1) an acid catalyzed, crosshnking resin system,
• a still further embodiment of this invention is a method for preparing a lithographic p ⁇ ntmg surface consistmg essentially of the steps
• porous hydrophilic layer applied to the sheet substrate, wherein the porous hydrophilic layer consists essentially of aluminosilicate, and
• Figure 1 is an electron micrograph of an aluminosilicate surface of the porous hydrophilic layer of this invention.
• Figure 2 is an electron micrograph of an imaging layer coated over the porous hydrophilic layer.
• Figure 3 is an electron micrograph of an imaged imaging layer coated over the porous hydrophilic layer.
• This invention relates to processless thermal lithographic printing plates which can be digitally imaged by infrared laser light having a wavelength between 700 and 1300 nm.
• the thermal lithographic printing plates described herein do not require a chemical development to remove areas of the imaged plate. Rather, upon exposure to infrared laser light, the imaged areas become ink receptive and the non-image areas repel ink after simple treatment with a conditioner such as a fountain solution.
• the processless thermal lithographic printing plates of this invention is comprised of a sheet substrate; a porous, aluminosilicate hydrophilic layer applied to the sheet substrate; and a thermally reactive imaging layer applied to the hydrophilic layer.
• the substrate may be polymeric films such as polyester films; metal sheets such as aluminum; paper product sheets; and the like. Each of these substrate types may be coated with ancillary layers to improve interlayer adhesion; thermal insulation, particularly for metal substrates; and the like.
• the substrate is a sheet of polyester film such as polyethylene terephthalate, although other polymeric films and composites may also be used such as polycarbonate sheets; and the like.
• a particularly preferred sheet substrate is Myriad polyester offset substrate which is available from Xante Corporation, Mobile, AL. Myriad polyester offset substrate consists of a polyester substrate which has been treated to provide a hydrophilic surface. Porous Hydrophilic Layer
• the lithographic plate of this invention contains an aluminosilicate hydrophilic layer which is porous and which strongly adheres to both the underlying substrate as well as the overlying imaging layer
• a particular hydrophilic layer which possesses these unique features is the hydrophilic surface of the Myriad polyester offset p ⁇ nting plate identified above
• the hydrophilic surface of the product was analyzed using an FT-1R spectrophotometer and identified as alumino silicate corresponding to A1 2 0 • 2S ⁇ 0 2 • 2H 2 0
• An electron micrograph of that hydrophilic surface at 5 KV electrons and 2000 magnification as illustrated in Figure 1 revealed that the surface is micro-porous having pores which are a fraction of a micrometer
• the Mynad product was determined to have an average surface roughness of about 1 0 to about 1 1 micrometers, using conventional roughness measurement methods
• the imaging layer of this invention is thermally reactive and contains a composition which strongly absorbs infrared radiation which induces a thermal reaction in the composition to change its physical properties
• the imaging layer is porous although visually the coating appears uniform and continuous Referring to Figure 2, this figure is an electron micrograph at 5 KV electrons and 2000 magnification which illustrates that the surface of a uniform polyme ⁇ c coating is micro-porous
• the composition of the imagmg layer contains as its essential ingredients an acid catalyzed, crosshnking resin system, a thermal-activated acid generator, an infrared absorbing compound, and optionally, an indicator dye
• the acid catalyzed, crosslinking resin system comp ⁇ ses an acid catalyzed crosslinkable polymer capable of undergoing an acid-catalyzed polyme ⁇ zation and/or crosshnking reaction, at a temperature in the range of about 60-200°C, to form a crosshnked polymer
• the crosshnking resm system contains as its sole component an acid catalyzed crosslinkable polymer which contains functional groups which allows crosslinking between polymer chains of the resin system
• the crosshnking resm system contains both the acid catalyzed crosslinkable polymer and a binder resin comp ⁇ smg a polymer containing reactive pendent groups selected from the group consisting of hydroxy, carboxyhc acid, sulf
• the crosslinking resins used m the imagmg layer of this mvention preferably are resole resms, C1.-C5 alkoxymethyl melamme and glycolu ⁇ l resms; polymers of (hydroxymethyl styrene), of (4-methoxymethyl styrene), of
• Crosshnking resms which are particularly preferred are copolymers of N-methoxymethyl methacrylamide, of N-methoxymethyl acrylamide, or of hydroxy-((l-oxo-2-propenyl)-am ⁇ no) acetic acid methyl ester, with d -Cn alkylacrylate, with Cj - C ⁇ 2 alkylmethacrylate, with glycidylmethacrylate, with 3,4-epoxy cyclohexylmethyl methacrylate, with 3,4-epoxy cyclohexylmethyl aery late, with acrylic acid, and with methacryhc acid
• the cross nking resin is incorporated into the composition in an amount from about 25 to about 90, and preferably about 40 to about 75, weight percent (based on the weight of the composition)
• the binder resin used in the imagmg layer of this invention preferably is one or more polymers capable of undergoing an acid-catalyzed condensation reaction with the crosshnking resm at a temperature in the range of about 60 to 200°C to form a crosshnked polymer
• Suitable examples of such polymers include poly(4-hydroxystyrene), poly(4-hydroxystvrene/methyl- methacrylate), novolac resin, poly(2-hydroxyethylmethacrylate/cyclohexylmethacrylate).
• the bmder resin is present m the composition in an amount of 0 to about 65, and preferably up to about 50, weight percent (based on the weight of the composition)
• thermal-activated acid generator used in the imaging layer of this invention promotes the matrix-forming reaction between the crosslinking resin and the bmder resin when the layer is exposed to a suitable radiation source
• Thermal-activated acid generators suitable for use in this invention mclude, for example, straight or branched-cham Ci -C 5 alkyl sulfonates, aryl sulfonates, straight or branched cham N- Ci -C 5 alkyl sulfonyl sulfonamides, salts contammg an onium cation and nonnucleophihc anion, and combmations thereof
• Particularly useful salts m include those in which the onium cation is selected from the group consisting of an lodomum, a sulphomum, a phosphonium, a oxysulphoxomum, a oxysulphomum, a sulphoxomum, an N-alkoxy ammonium, an am
• mfrared dyes employed in the imagmg layer are Cyasorb IR99 (available from Glendale Protective Technology), Cyasorb IR165 (available from Glendale Protective Technology), Epolite III- 178 (available from Epoline), Epolite IV-62B (available from Epoline), PINA-780 (available from Allied Signal), SpectraIR830A (available from Spectra Colors Corp ), and SpectraIR840A (available from Spectra Color
• imaging layer Other components which can optionally be incorporated into the imaging layer include an indicator dye and a secondary acid generator
• an indicator dye is typically added to the imaging layer to provide a visual image on the exposed plate p ⁇ or to mkmg or mounting on the press
• Suitable indicator dyes for this purpose include Basic Blue 7, CI Basic Blue 11, CI Basic Blue 26, CI Disperse Red 1, CI Disperse Red 4, CI Disperse Red 13, Victo ⁇ a Blue R, Victo ⁇ a Blue BO, Solvent Blue 35, and Solvent Blue 36 preferably the imagmg layer contains an indicator dye which is present in an amount of about 0 05 to about 10 weight percent and preferably from about 0 1 to about 5 weight percent, based on the weight of the composition
• Suitable secondary acid generators are those capable of undergoing an acid-catalyzed thermal decomposition to form additional acid Secondary acid generators of this type include acetoacetate, a squa ⁇ c acid derivative, or an oxalic acid denvative Particularly useful secondary acid generators include tert-butyl-2-methyl-2-(tosyloxymethyl)-acetoacetate,
• the coated plate is dried with the aid of an airstream having a temperature from about 60 to about 100°C for about 0 5 to 10 minutes
• the resultmg plate will have an imaging layer having a coating weight below about 3 grams per square meter and preferably between about 1 5 and about 2 5 grams per square meter
• a lithographic p ⁇ ntmg surface is prepared using a lithographic p ⁇ nting plate as desc ⁇ bed supra which compnses a sheet substrate, a porous hydrophilic layer applied to the sheet substrate, wherein the porous hydrophilic layer consists essentially of aluminosilicate, and an imagmg layer applied to the hydrophilic layer, wherem the imaging layer comprises a thermally reactive composition
• the imaging layer is imagewise exposed to frared radiation to produce an imaged layer, and the imaged layer is treated with a conditioner liquid to produce a planar lithographic p ⁇ ntmg surface
• the lithographic p ⁇ nting plates of this invention are imagewise exposed by a radiation source that emits in the infrared region, I e .
• the mfrared radiation is laser radiation
• the lithographic p ⁇ nting plates of this invention are uniquely adapted for ' " direct-to-plate" imagmg
• Direct-to-plate systems utilize digitized information, as stored on a computer disk or computer tape, which is intended to be p ⁇ nted
• the bits of information in a digitized record correspond to the image elements or pixels of the image to be p ⁇ nted
• the pixel record is used to control an exposure device which may, for example, take the form of a modulated laser beam
• the position of the exposure beam, m turn may be controlled by a rotating drum, a leadscrew, or a turning mirror
• the exposure beam is then turned off m correspondence with the pixels to be pnnted
• the exposing beam is focused onto the imaging layer of the unexposed plate
• the plate to be exposed is placed in the retaining mechanism of the wnting device and the w ⁇ te laser beam is scanned across the plate and digitally modulated to generate an image on the surface of the lithographic plate
• an mdicator dye is present m the imagmg layer a visible image is likewise produced on the surface of the plate
• this figure is an electron micrograph at 5 KV electrons and 2000 magnification which illustrates that the surface of an imaged uniform polymenc coating is micro-porous at least in the non-imaged areas
• the conditioner liquid may be a conventional fountain solution which is applied to the lithographic plate the conventional way on a lithographic printing press
• the conditioner liquid may be an aqueous surfactant solution which is applied to the imaged surface, for example by wiping with a solution saturated applicator, and wherem the treated plate is then directly placed on the printing press and the p ⁇ nting operation begun
• the treated lithographic p ⁇ ntmg surface is truly a planar surface in contrast to the shallow relief image of conventional plates resulting from washout development
• a unique feature of the lithographic p ⁇ nting plate of this invention is that it can be used directly on a lithographic p ⁇ nting press without such a washout development step required by conventional tho plates Such a feature further enhances the efficiency of direct-to-plate imaging systems in that it eliminates plate development processing
• the aqueous surfactant solution typically has a pH between about 3 and about 13, and contains about 0 2 to about 15 weight percent of a surfactant based on the weight of the conditioner liquid, and preferably between about 2 to about 12 weight percent
• the surfactant used m the conditioner liquid preferably is an amphot
• the aqueous surfactant solution may be a conventional fountain solution to which the surfactant has been added or it may be an alkaline solution such as the developer solutions disclosed in U S Patent 3,891,439 cited supra
• a suitable alkaline solution of this type is a conventional developer, such as the developer disclosed m example 1 of U S Patent 3,891,439, which contains about 11 % of the lmidazoline based amphotenc CYNA-50 surfactant (hereinafter identified as Surfactant Solution I)
• Example 1 The substrate used for making the lithographic p ⁇ ntmg plate was Mynad film base, a product of Xante Corporation, Mobile, Alabama Myriad® film base is a hydrophilic surface treated polyester film
• the hydrophilic surface was analyzed using a FT-IR spectrophotometer and identified as alumino silicate corresponding to A O ⁇ • 2S ⁇ 0 2 • 2H 2 0 and an electron micrograph at 5 KV electrons and 2000 magnification ( Figure l)revealed that the hydrophilic surface is micro-porous
• the polyme ⁇ c coatmg solution was prepared by dissolving 4 0 g poly(N-methoxy methyl methacrylam ⁇ de-co-3,4-epoxycyclohexylmethyl methacrylate) hereinafter ACR1290 (available from
• the plate was imaged on a Creo Trendsetter thermal plate setter, which was equipped with solid state diode lasers having a wavelength at around 830 nm, at an energy density between 200 and 500 mJ/cm 2
• the imaged plate was mounted on press and wetted with Surfactant Solution I (desc ⁇ bed supra) as a conditioner solution
• Surfactant Solution I (desc ⁇ bed supra) as a conditioner solution
• the plate produced more than 50.000 copies without any dete ⁇ oration
• the polyme ⁇ c coatmg solution was prepared similar to Example 1, except that SpectraIR1060A infrared dye was used to replace SpectraIR830A dye
• the solution was spin coated on the hydrophilic surface of the My ⁇ ad polyester offset substrate and 85 rpm and dned at 60° C for 3 mmutes to produce a uniform polyme ⁇ c coatmg having a coatmg weight between 0 4 and 1 0 g/m 2
• the plate was imaged on the Creo Trendsetter thermal plate setter, which was equipped with solid state diode lasers having a wavelength at around 830 nm, at an energy density between 200 and 500 mJ/cm 2
• the imaged plate was mounted on press and wetted the conditioner solution of Example 1
• the plate produced more than 50,000 copies without any dete ⁇ oration Example 3
• the polyme ⁇ c coating solution was prepared similar to Example 1, except that poly(v ⁇ nylphenol-co-2-hydroxyethylmethacrylate) was used to replace the GPRJ-7550 phenolic resin
• the solution was spin coated on the hydrophilic surface of the My ⁇ ad polyester offset substrate and 85 ⁇ m and d ⁇ ed at 60° C for 3 minutes to produce a uniform polyme ⁇ c coating having a coatmg weight between 0 4 and 1 0 g/m 2 .
• the plate was imaged on the Creo Trendsetter thermal plate setter, which was equipped with solid state diode lasers having a wavelength at around 830 nm. at an energy density between
• Example 1 The imaged plate was mounted on press and wetted a conditioner solution of Example 1 The plate produced more than 50,000 copies without any deterioration
• Example 4 The polyme ⁇ c coating solution was prepared similar to Example 1. except that 0 6 g poly(hydroxy((l-oxo-2-propenyl)am ⁇ no)acet ⁇ c ac ⁇ d-co-3,4-epoxy cylohexylmethyl methacrylate) was used to replace poly(N-methoxy methyl methacrylam ⁇ de-co-3,4-epoxy cyclohexyl methyl methacrylate) copolymer The solution was spin coated on the hydrophilic surface of the My ⁇ ad polyester offset substrate and 85 ⁇ m and d ⁇ ed at 60° C for 3 mmutes to produce a umform polyme ⁇ c coatmg having a coatmg weight between 0 5 and 1 0 g/m 2
• the plate was imaged on the Creo Trendsetter thermal plate setter, which was equipped with solid state diode lasers having a wavelength at around 830 nm, at an energy density between 200 and 500 mJ/cm 2
• the imaged plate was mounted on press and wetted a conditioner solution of Example 1
• the plate produced more than 50,000 copies without any dete ⁇ oration
• Example 5 The polyme ⁇ c coatmg solution was prepared by dissolving 4.0 g ACR1290, 0.8g CD1012,
• the plate was imaged on the Creo Trendsetter thermal plate setter, which was equipped with solid state diode lasers having a wavelength at around 830 nm, at an energy density between 200 and 500 mJ/cm 2
• the imaged plate was mounted on press and wetted a conditioner solution
• Example 1 The plate produced more than 50,000 copies without any dete ⁇ oration
• Example 6 The plate produced more than 50,000 copies without any dete ⁇ oration
• a lithographic p ⁇ nting plate was prepared and imaged as desc ⁇ bed in Example 1
• the imaged plate was mounted on a press supplied with a conventional fountain solution to which 4 weight % of CYNA-50 (an amphote ⁇ c surfactant available from Mona Indust ⁇ es, Patterson, N J ) had been added After the initial start-up impressions were made, the plate produced more than

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• Physics & Mathematics (AREA)
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• Ceramic Engineering (AREA)
• Inorganic Chemistry (AREA)
• Thermal Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Printing Plates And Materials Therefor (AREA)
• Photosensitive Polymer And Photoresist Processing (AREA)
• Materials For Photolithography (AREA)

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• 1998
  • 1998-08-14 DE DE69804230T patent/DE69804230T2/de not_active Expired - Fee Related
  • 1998-08-14 EP EP98939400A patent/EP1015244B1/de not_active Expired - Lifetime
  • 1998-08-14 JP JP2000508533A patent/JP2001514103A/ja active Pending
  • 1998-08-14 WO PCT/US1998/016885 patent/WO1999011457A1/en active IP Right Grant

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