PROCESSLESS, LASER IMAGEABLE LITHOGRAPHIC PRINTING PLATE

Abstract: A lithographic printing surface is prepared using a thermal lithographic printing plate which requires no chemical development to remove areas of the imaged plate. The processless thermal lithographic printing plate has a sheet substrate; a porous, aluminosilicate hydrophilic layer on the sheet substrate; and a porous, thermally reactive imaging layer on the hydrophilic layer. The imaging layer is imaged using infrared laser radiation to produce an imaged layer. The imaged layer is treated with a conditioner liquid to produce a porous, planar, lithographic printing surface. By this method, the printing plate can be digitally imaged by infrared laser so that the imaged areas become ink receptive and the non-image area repel ink after simple treatment with a conditioner such as an aqueous surfactant solution such as a fountain solution containing an amphoteric surfactant.

Description: DESCRIPTION PROCESSLESS. LASER IMAGEABLE LITHOGRAPHIC PRINTING PLATE BACKGROUND OF THE INVENTION Field of the Invention This invention relates to lithographic pπnting plates and their process of use More particularly, this invention relates to lithographic printing plates which can be digitally imaged by infrared laser light Descnption of Related Art 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 Duπng development of the imaged plate, 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 During printing, 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 pπnted 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 pπnting plate With the advent of digitally controlled imaging systems using infrared lasers, printing plates which can be imaged thermally have been developed to address the emerging industry need In such thermally imaged systems 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 However, 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. Examples of radiation sensitive compositions and their use in making lithographic pπntmg plates are disclosed in U.S Patents 4,708,925, 5,085,972, 5,286,612, 5,372,915, 5,441,850, 5,491,046, 5,340,699, and 5,466,557, and European Patent Application 0 672 954 A2 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 pπnting areas are removed the developed plate typically requires nnsing and drying pnor to mounting on the printing press In order to take full advantage of current digitally controlled imaging systems there is a need to reduce or eliminate the time required for plate development so that an imaged plate could be directly used on a pπnting press SUMMARY OF THE INVENTION These needs are met by the processless lithographic printing plate of this invention which is a lithographic pπnting plate compπsmg (a) a sheet substrate, (b) a porous hydrophilic layer applied to the sheet substrate, wherein the porous hydrophilic layer consists of aluminosilicate, and (c) 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 pπnting plate compπsing (a) a sheet substrate, (b) a porous hydrophilic layer applied to the sheet substrate, wherein the porous hvdrophilic layer consists essentially of aluminosilicate, and (c) an imagmg layer applied to the hydrophilic layer, wherein the imaging layer consists essentially of (1) an acid catalyzed, crosshnking resin system, (2) a thermal-activated acid generator, (3) an infrared absorbing compound, and optionally, (4) an indicator dye A still further embodiment of this invention is a method for preparing a lithographic pπntmg surface consistmg essentially of the steps A providing a lithographic pπntmg plate compnsmg (a) a sheet substrate, (b) a porous hydrophilic layer applied to the sheet substrate, wherein the porous hydrophilic layer consists essentially of aluminosilicate, and (c) an imaging layer applied to the hydrophilic layer, wherein the imaging layer compπses a thermally reactive composition, B imagewise exposing the imaging layer to infrared radiation to produce an imaged layer, and C treatmg the imaged layer with a conditioner liquid to produce a planar lithographic pnntmg surface BRIEF DESCRIPTION OF THE DRAWINGS The invention can be more fully understood from the following description thereof in connection with the accompanying drawings described as follows: 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. DETAILED DESCRIPTION OF THE INVENTION 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. Sheet Substrate Any dimensionally stable sheet material may be used to support the lithographic plate structure of this invention. Thus 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. Preferably, 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 pπnting 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 • 2Sι0 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 Thermally Reactive Imaging Layer 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 polymeπc 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 compπses an acid catalyzed crosslinkable polymer capable of undergoing an acid-catalyzed polymeπzation and/or crosshnking reaction, at a temperature in the range of about 60-200°C, to form a crosshnked polymer In one embodiment of this invention, 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 In another embodiment, the crosshnking resm system contains both the acid catalyzed crosslinkable polymer and a binder resin compπsmg a polymer containing reactive pendent groups selected from the group consisting of hydroxy, carboxyhc acid, sulfonamide, hydroxymethyl amide, and alkoxymethyl amide, wherein the binder resm is capable of undergoing an acid-catalyzed polymeπzation and/or crosshnking reaction with the acid catalyzed crosslinkable polymer, at a temperature in the range of about 60-200°C, to form the crosslinked polymer Condensation polymerization compositions of this type are disclosed in Assignee's U S Patent Application Serial No 08/745,534 The crosslinking resins used m the imagmg layer of this mvention preferably are resole resms, C1.-C5 alkoxymethyl melamme and glycoluπl resms; polymers of (hydroxymethyl styrene), of (4-methoxymethyl styrene), of |(N-methoxymethyl)-acrylamιde|. and of f(N-n-butoxymethyl)- acrylamide ' , and combinations thereof Crosshnking resms which are particularly preferred are copolymers of N-methoxymethyl methacrylamide, of N-methoxymethyl acrylamide, or of hydroxy-((l-oxo-2-propenyl)-amιno) acetic acid methyl ester, with d -Cn alkylacrylate, with Cj - Cι 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). poly(2- hydroxyethylmethacrylate/methylmethacrylate), poly(styrene/butylmethacrylate/methyl- methacrylate/methacrylic acid), poly(butylmethacrylate/methacryhc acid), poly(vιnylphenol/2- hydroxyethylmethacrylate), poly(styrene/n-butylmethacrylate/(2-hydroxyethyl methacrylate/ methacryhc acid), poly( J-memoxymemylmethylacιylamιde/2-phenylethylmethacrylate/ methacryhc acid), and poly(styrene/ethylmethacrylate/2-hydroxyethylmethacrylate/methacryhc acid) 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) The 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 mclude 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 ammonium, or a diazomum cation and where the non-nucleophihc anion is selected from the group consisting of tetrafluoroborate, hexafluorophosphate, hexafluoroarsenate, hexafluoroantimonate, tπflate, tetrakιs(pentafluorophenyl)borate, pentafluoroethylsulfonate, p-methylbenzene sulfonate, ethyl sulfonate, tπfluoromethyl acetate, and pentafluoroethyl acetate Preferred thermal-activated acid generators are diaryhodonium salts A particularly preferred thermal-activated acid generator is a C 3 - C 2 o alkoxyphenyl-phenyhodonium salt, or a C 3 - C 2 o alkoxyphenyl-phenyhodonium salt wherem the alkoxv group is substituted at the 2 position with a hydroxy group such as 2-hydroxy- tetradecyloxyphenyl-phenyhodonium hexafluoroantimonate, or an ester linkage is present m the alkoxy group chain The thermal-activated acid generator is incorporated m the imaging layer in an amount from about 1 to about 25 weight percent and preferably from about 5 to about 20 weight percent, based on the weight of the composition The imaging layer of this invention also requires, as a component, an mfrared absorber to render the layer sensitive to infrared radiation and cause the printing plate to be imageable by exposure to a laser source emitting in the infrared region The infrared absorbing compound may be a dye and/or pigment, typically having a strong absorption band in the region between 700 nm and 1400 nm. and preferably m the region between 780 nm and 1300 nm A wide range of such compounds is well known in the art and include dyes and/or pigments selected from the group consisting of tπarylamme dyes, thiazohum 5'es, indolium dyes, oxazohum dyes, cyanine dyes, polyanilme dyes, polypyrrole dyes, polythiophene dyes, thiolene metal complex dyes, carbon black, and polymeric phthalocyanine blue pigments Examples of the 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 Colors Corp ) The infrared absorber is used in the imaging layer in an amount from about 2 to about 30 weight percent, percent and preferably from about 5 to about 20 weight percent, based on the weight of the composition 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 pπor 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, Victoπa Blue R, Victoπa 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 squaπc acid derivative, or an oxalic acid denvative Particularly useful secondary acid generators include tert-butyl-2-methyl-2-(tosyloxymethyl)-acetoacetate, 2-phenyl-2-(2- tosyloxyethyl)-l,3-dιoxolane and 3,4-dιalkoxycyclobut-3-ene-l,2-dιone To form printing plates of this invention , the compositions typically may be dissolved m an appropπate solvent or solvent mixture, to the extent of about 5 to 15 weight percent based on the weight of the composition Appropriate solvents or solvent mixtures include methyl ethvl ketone, methanol, methyl lactate, etc Desirably, the coating solution will also contain a typical sihcone- type flow control agent The porous hydrophilic layer on the sheet substrate may be coated by conventional methods, e g , roll, gravure, spin, or hopper coating processes, at a rate of about 5 to 15 meters per minute 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 Preparation of the Lithographic Pnnting Surface In the method of this invention, a lithographic pπntmg surface is prepared using a lithographic pπnting plate as descπbed 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 pπntmg surface The lithographic pπnting plates of this invention are imagewise exposed by a radiation source that emits in the infrared region, I e . between about 700 nm and about 1.400 nm Preferably, the mfrared radiation is laser radiation Such laser radiation may be digitally controlled to imagewise expose the imagmg layer In this context, the lithographic pπnting 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 pπnted The bits of information in a digitized record correspond to the image elements or pixels of the image to be pπnted 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 Durmg the writing operation, the plate to be exposed is placed in the retaining mechanism of the wnting device and the wπte laser beam is scanned across the plate and digitally modulated to generate an image on the surface of the lithographic plate When an mdicator dye is present m the imagmg layer a visible image is likewise produced on the surface of the plate Referπng to Figure 3, 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 After imaging exposure the imaged layer of the lithographic pπnting plate of this invention is treated with a conditioner liquid The conditioner liquid may be a conventional fountain solution which is applied to the lithographic plate the conventional way on a lithographic printing press Alternatively, 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 pπnting operation begun In either instance, the treated lithographic pπntmg 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 pπnting plate of this invention is that it can be used directly on a lithographic pπnting 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 amphoteπc surfactant such as those disclosed m U S Patent 3,8 1,439 the contents of which are incorporated herem by reference Column 4, l es 21 et seq of this patent descπbe amphoteπc surfactants which are substituted imidazolines prepared by reacting long cham imidazolines with halogenated or organic intermediates contammg carboxyl, phosphoπc, or sulfonic acid groups Amphoteπc surfactants of this type are Monateπcs available from Mona Industries, Inc , Patterson, NJ. particularly CYNA-50 surfactant 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) The lithographic pπnting plate of this mvention will now be illustrated by the following examples but is not mtended to be limited thereby Example 1 The substrate used for making the lithographic pπntmg 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^ • 2Sι0 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 polymeπc coatmg solution was prepared by dissolving 4 0 g poly(N-methoxy methyl methacrylamιde-co-3,4-epoxycyclohexylmethyl methacrylate) hereinafter ACR1290 (available from Polychrome Corp ), 2 0 g butylated, thermosetting phenolic resm (GPRJ-7550, 75% solid, available from Georgia Pacific), 0 8 g 2-hydroxy-tetradecyloxyphenyl-phenyhodonιum hexafluoroantimonate hereinafter CD 1012 (available from Sartomer), 0 8 g SpectraIR830A infrared dye (available from Spectra Colors Corp ) and 0 2 g of the mdicator dye Solvent Blue 35 (available from Spectra Colors Corp ) into 120 g solvent mixture containing 60% methyl ethyl ketone, 20% methanol, 20% ethyl cellosolve and a trace amount of FC430 surfactant The solution was spin coated on the hydrophilic surface of the Myπad polyester offset substrate at 85 rpm and dried at 60 ° C for 3 mmutes to produce a uniform polymenc coatmg having a coating weight between 0 4 and 1 0 g/m 2 An electron micrograph at 5 KV electrons and 2000 magnification (Figure 2) revealed that the uniform polymeπc coatmg surface is micro-porous 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 An electron micrograph at 5 KV electrons and 2000 magnification (Figure 3) revealed that the surface of the imaged uniform polymeric coatmg is micro-porous at least in the non-imaged areas The imaged plate was mounted on press and wetted with Surfactant Solution I (descπbed supra) as a conditioner solution The plate produced more than 50.000 copies without any deteπoration Example 2 The polymeπc 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 Myπad polyester offset substrate and 85 rpm and dned at 60° C for 3 mmutes to produce a uniform polymeπc 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 deteπoration Example 3 The polymeπc coating solution was prepared similar to Example 1, except that poly(vιnylphenol-co-2-hydroxyethylmethacrylate) was used to replace the GPRJ-7550 phenolic resin The solution was spin coated on the hydrophilic surface of the Myπad polyester offset substrate and 85 φm and dπed at 60° C for 3 minutes to produce a uniform polymeπc 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 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 deterioration Example 4 The polymeπc coating solution was prepared similar to Example 1. except that 0 6 g poly(hydroxy((l-oxo-2-propenyl)amιno)acetιc acιd-co-3,4-epoxy cylohexylmethyl methacrylate) was used to replace poly(N-methoxy methyl methacrylamιde-co-3,4-epoxy cyclohexyl methyl methacrylate) copolymer The solution was spin coated on the hydrophilic surface of the Myπad polyester offset substrate and 85 φm and dπed at 60° C for 3 mmutes to produce a umform polymeπc 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 deteπoration Example 5 The polymeπc coatmg solution was prepared by dissolving 4.0 g ACR1290, 0.8g CD1012, 0 8g mfrared dye SpectraIR830A and 0.2 g mdicator dye Solvent Blue 35, into 120 g solvent mixture contammg 60% methyl ethyl ketone, 20% methanol, 20% ethyl cellosolve and a trace amount of FC430 surfactant The solution was spm coated on the Myπad substrate of Example 1 at 85 φm and dπed at 60° C for 3 minutes to produce a uniform polymeπc 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 Example 1 The plate produced more than 50,000 copies without any deteπoration Example 6 A lithographic pπnting plate was prepared and imaged as descπbed 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 amphoteπc surfactant available from Mona Industπes, Patterson, N J ) had been added After the initial start-up impressions were made, the plate produced more than 50,000 copies without any deterioration Those skilled in the art having the benefit of the teachings of the present invention as hereinabove set forth, can effect numerous modifications thereto These modifications are to be construed as bemg encompassed within the scope of the present invention as set forth m the appended claims

Claims: What is claimed is 1 A lithographic pπnting plate compπsmg (a) a sheet substrate. (b) a porous hydrophilic layer applied to the sheet substrate, wherem the porous hydrophilic layer consists essentially of aluminosilicate, and (c) an imagmg la\ er applied to the hydrophilic layer, wherein the imagmg layer is porous and compπses a thermally reactive composition 2 The lithographic pπntmg plate of claim 1 wherem the sheet substrate is a dimensionally stable, polymeπc sheet 3 The lithographic pπnting plate of claim 2 wherein the sheet substrate is a polyethylene terephthalate film 4 The lithographic pπnting plate of claim 1 wherein the aluminosilicate is Al 2 O • 2 Sι0 • 2H 2 0 5 The lithographic pπnting plate of claim 1 wherem the imaging la>er has a coating weight between about 1 5 and about 2 5 grams per square meter 6 The lithographic printing plate of claim 1 wherein the thermally reactive composition consists essentially of (1) an acid catalyzed, crosslinking resin system, (2) a thermal-activated acid generator, (3) an mfrared absorbmg compound, and optionally, (4) an indicator dye 7 The lithographic pπntmg plate of claim 1 wherem the acid catalyzed, crosshnking resin system compπses an acid catalyzed crosslinkable polymer capable of imdergomg an acid-catalyzed condensation reaction, at a temperature in the range of about 60-200°C, to form a crosshnked polymer 8 The lithographic printing plate of claim 7 wherem the acid catalyzed, crosslinking resm system contains the acid catalyzed crosslinkable polymer and a binder resm compnsmg a polymer contammg reactive pendent groups selected from the group consistmg of hydroxy, carboxyhc acid, sulfonamide, hydroxymethyl amide, and alkoxymethyl amide, and wherem the bmder resin is capable of undergomg an acid-catalyzed condensation reaction with the acid catalyzed crosslinkable polymer, at a temperature m the range of about 60-200°C, to form the crosslinked polymer 9 The lithographic pπnting plate of claim 7 wherein the acid catalyzed, crosslinkable polymer is selected from the group consistmg of resole resms, Cj-C 5 alkoxymethyl melam e and glycoluπl resms, polymers of (hydroxymethyl styrene), of (4-methoxymethyl styrene), of [(N- methoxymethyl)-acrylamιde], and of [(N-n-butoxymethyl)-acrylamιde], and combinations thereof 10 The lithographic pπntmg plate of claim 7 wherem the acid catalyzed, crosslinkable polymer is a copolymer of N-methoxymeϋryl methacrylamide, of N-methoxymetltyl acrylamide, or of hydroxy-((l-oxo-2-propenyl)-amιno) acetic acid, with d -C 12 alkylacrylate. with d -Cι 2 alkylmethacrylate. with glycidylmethacrylate. with 3,4-epoxy cyclohexylmethyl methacrylate, with 3.4-epoxy cyclohexylmethyl acrylate. with acrylic acid, and with methacryhc acid methyl ester 1 1 The lithographic pnntmg plate of claim 8 wherem the bmder resin is selected from the group consisting of poly(4-hydroxystyrene), poly(4-hydroxystyrene/methylmethacrylate), novolac resin, poly(2-hydroxyethylmethacrylate/cyclohexylmethacrylate), poly(2-hydroxyethylmethacrylate/ methyhnethacrylate), poly(styrene/butylmethacrylate/methylmethacrylate/methacrylιc acιd), poly(butylmethacrylate/methacrylιc acid), poly(vιnylphenol/2-hydroxyethylmethacrylate), poly(styrene/n-butylmethacrylate/(2-hydroxyethyl methacrylate/methacrylic acid), poly(N- methoxymethyl-methylacrylamιde/2-phenylethylmethacrylate/ methacryhc acid), and poly(styrene/e ylme acιylate/2-hydroxyemylmeΛacrylate/methacryhc acιd) 12 The lithographic pnntmg plate of claim 6 wherem the thermal-activated acid generator is selected from the group consisting of straight or branched-chain Ci -C<; alkyl sulfonates, aryl sulfonates, straight or branched cham N- Ci -C 5 alkyl sulfonyl sulfonamides, salts contammg an onium cation and nonnucleophihc anion, and combinations thereof 13 The lithographic pnntmg plate of claim 12 wherem the salt contams a non-nucleophihc anion selected from the group consisting of tetrafluoroborate, hexafluorophosphate, hexafluoroarsenate, hexafluoroantimonate, triflate, tetrakιs(pentafluorophenyl)borate, pentafluoroethylsulfonate, p-methylbenzene sulfonate, ethyl sulfonate, tnfluoromethyl acetate, and pentafluoroethyl acetate 14 The lithographic prmtmg plate of claim 6 wherem the thermal-activated acid generator is a salt containing an lodomum, a sulphonium, a phosphonium, a oxysulphoxomum, a oxysulphonium, a sulphoxonium, an N-alkoxyammonium, an ammonium, or a diazonium cation 15 The lithographic prmtmg plate of claim 6 wherem the thermal-activated acid generator is an N-alkoxy isoquinolinium salt, a tπarylsulfonium salt or a diaryhodonium salt 16 The lithographic pnntmg plate of claim 6 wherein the thermal-activated acid generator is a C 3 - C 2 o alkoxyphenyl-phenyhodonium salt, or a C 3 - C 2u alkoxyphenyl-phenyhodonium salt wherein the alkoxy group is substituted at the 2 position with a hydroxy group, or an ester linkage is present in an alkoxy group chain of the alkoxy group 17 The lithographic prmtmg plate of claim 6 wherem the thermal-activated acid generator is 2-hydroxy-tetradecyloxyphenyl-phenvlιodonιum hexafluoroantιmonate 18 The lithographic pnntmg plate of claim 6 wherem the infrared absorbmg compound is a dye and/or pigment having a strong absoφtion band m the region between 700 nm and 1400 nm 19 The lithographic printing plate of claim 6 wherein the mfrared absorbmg compound is selected from the group consisting of tnarylamine dyes, thiazohum dyes, mdolium dyes, oxazohum dyes, cyanine dyes, polyanilme dyes, polypyrrole dyes, polythiophene dyes, thiolene metal complex dyes, carbon black, and polymeπc phthalocyamne blue pigments 20 The lithographic pnntmg plate of claim 6 wherem the indicator dye is present in the imaging layer, and wherem the mdicator dye is selected from the group consistmg of Victoria Blue R, Victoπa Blue BO, Solvent Blue 35, and Solvent Blue 36 21 A lithographic pπnting plate compnsing (a) a sheet substrate, (b) a porous hydrophilic layer applied to the sheet substrate, wherem the porous hydrophilic layer consists essentially of aluminosilicate, and (c) an imagmg layer applied to the hydrophilic layer, wherein the imagmg layer consists essentially of (1) an acid catalyzed, crosshnking resm system, (2) a thermal-activated acid generator, (3) an mfrared absorbmg compound; and optionally, (4) an mdicator dye 22 A method for prepaπng a lithographic pnntmg surface consisting essentially of the steps: A. providing a lithographic prmting plate compnsmg. (a) a sheet substrate; (b) a porous hydrophilic layer applied to the sheet substrate, wherein the porous hydrophilic layer consists essentially of aluminosilicate; and (c) an imaging layer applied to the hydrophilic layer, wherein the imaging layer compπses a thermally reactive composition; B imagewise exposmg the imaging layer to infrared radiation to produce an imaged layer, and C. treating the imaged layer with a conditioner liquid to produce a planar lithographic pπntmg surface. 23. The method of claim 22 wherein the mfrared radiation is laser radiation 24 The method of claim 23 wherein the laser radiation is digitally controlled to imagewise expose the imaging layer. 25 The method of claim 22 wherem the conditioner liquid is an aqueous surfactant solution 26 The method of claim 25 wherem the conditioner liquid contains an amphoteπc surfactant. 27. The method of claim 25 wherem the amphoteπc surfactant is an lmidazohne based surfactant. 28 The method of claim 25 wherem the conditioner liquid has a pH between about 3 and about 13. 29 The method of claim 25 wherem the conditioner liquid contains about 0.2 to about 15 weight percent of a surfactant based on the weight of the conditioner liquid. 30 The method of claim 25 wherem the conditioner liquid is a fountain solution 31 The method of claim 25 wherem the conditioner liquid is an alkalme solution 32 The method of claim 22 wherem the conditioner liquid is a fountain solution 33 The method of claim 22 wherem the thermally reactive composition consists essentially of (1) an acid catalyzed, crosslinking resin system, (2) a thermal-activated acid generator. (3) an mfrared absorbing compound, and optionally, (4) an indicator dye 34 The method of claim 22 wherem the imaging layer is porous

Inventors: HALLMANN ROBERT, NATU OMKAR J, NGUYEN MY T, PAPPAS S PETER, SARAIYA SHASHIKANT, SHIMAZU KEN-ICHI, HALLMANN, ROBERT, NATU, OMKAR, J., NGUYEN, MY, T., PAPPAS, S., PETER, SARAIYA, SHASHIKANT, SHIMAZU, KEN-ICHI
Applicants: KODAK POLYCHROME GRAPHICS
Application year: 1998
Main classification: B41C1
IPC codes: B41C1, B41M5, B41N1