THERMAL LITHOGRAPHIC PRINTING PLATES

Abstract: A method for directly imaging a lithographic printing surface using infrared radiation without the requirement of pre- or post-UV-light exposure, or heat treatment employs a printing plate which contains a support with a hydrophilic surface overcoated with an imaging layer. The imaging layer contains at least one polymer having bonded pendent groups which are hydroxy, carboxylic acid, tert-butyl-oxycarbonyl, sulfonamide, amide, nitrile, urea, or combinations thereof; as well as an infrared absorbing compound. The imaging layer may contain a second polymer which has bonded pendent groups which are 1,2-naphthoquinone diazide, hydroxy, carboxylic acid, sulfonamide, hydroxymethyl amide, alkoxymethyl amide, nitrile, maleimide, urea, or combinations thereof. The imaging layer may also contain a visible absorption dye, a solubility inhibiting agent, or both. In practice, the imaging layer is imagewise exposed to infrared radiation to produce exposed image areas in the imaged layer which have transient solubility in aqueous alkaline developing solution so that solubility is gradually lost over a period of time until the imaged areas become as insoluble as non-imaged areas. Within a short time period of the imaging exposure, the imaged layer is developed with an aqueous alkaline developing solution to form the lithographic printing surface. In this method, the infrared radiation preferably is laser radiation which is digitally controlled.

Description: DESCRIPTION THERMAL LITHOGRAPHIC PRINTING PLATES BACKGROUND OF THE INVENTION Field of the Invention This invention relates to lithographic printing 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 pπnting plates typically have a radiation sensitive, oleophilic image layer coated over a hydrophi c 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 During development of the imaged plate, the soluble areas are removed by the developer liquid from underlying hydrophihc surface areas to produce a finished plate with ink receptive oleophilic image areas separated by complimentary, fountain solution receptive hydrophihc areas Duπng pπnting, a fountain solution is applied to the imaged plate to wet the hydrophihc areas, so as to insure that only the oleophilic image areas will pick up ink for deposition on the paper stock as a printed image Conventional lithographic pnnting 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- bakmg 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 pπnting 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, European Patent Application 0 672 954 A2, and WO 96/20429 U S Patent 5,372,915 is an example of a pnnting plate containing a radiation sensitive composition which is compπsed of a resole resm, a novolac resin, a latent Broensted acid and an lnfrared absorber In the preparation of a lithographic printing plate, the radiation sensitive composition is imagewise exposed to activating infrared radiation and the exposed areas of the pπnting plate are removed with an aqueous alkaline developing solution Related U S Patent 5,340,699 discloses the preparation of a lithographic printing plate using the same radiation sensitive composition as in U S Patent 5,372,915 But m this related patent the radiation sensitive composition is imagewise exposed to activatmg radiation, and then the printing plate is heated to provide reduced solubility in exposed areas and increased solubility in unexposed areas The unexposed areas of the pπnting plate are then removed with an aqueous alkaline developing solution Although the composition is the same, a positive or a negative lithographic image is produced m each respective patent by varying the activating radiation and adding a blanket heatmg step WO 96/20429 is an example of forming a negative lithographic image from a positive working photosensitive composition comprising a naphthoqumone diazide ester and a phenolic resin In the disclosed method the photosensitive composition is first uniformly exposed to ultraviolet radiation to render the composition developable The plate is then imaged with an infrared laser to rnsolubihze the imaged areas Those areas not exposed by the laser are then removed with a developer While advances have been made to provide negative working pπnting plates \\ ith infrared laser radiation, there continues to be a need for a simplified process to manufacture long-run positive working lithographic pπnting plates S MMARY OF THE INVENTION These needs are met by the positive working plate forming process of this invention which is a method for forming a lithographic pπnting surface consisting essentially of the following steps carried out in the order given (a) providing a lithographic printing plate compnsing a support having a hydrophihc surface and an imaging layer applied to the hydrophihc surface, the imaging layer compπsmg, (1) a polymer havmg a plurality of pendent groups bonded thereto wherein the pendent groups are selected from the group consisting of hydroxy, carboxylic acid, sulfonamide, amide, nitπle, urea, and combinations thereof, and (2) an infrared absorbing compound, (b) imagwise exposmg the imaging layer to infrared radiation to produce exposed image areas which have transient solubility in an aqueous alkaline developing solution, and, (c) contacting the imaging layer with the aqueous alkaline developing solution to remove the exposed image areas from the hydrophihc surface to form the lithographic printing surface comprised of unexposed image areas Preferably, the imaging layer is contacted with the aqueous alkaline developing solution within a time period of 20 hours from the imagewise exposing of the imaging layer An added embodiment of this invention is a lithographic printing plate compnsmg a support and an imaging layer consisting essentially of (1) a polymer having a plurality of pendent groups bonded thereto wherein the pendent groups are selected from the group consisting of hydroxy, carboxylic acid, sulfonamide, amide, nitnle, urea, and combinations thereof, (2) an infrared absorbing compound, and optionally, (3) a visible absoφtion dye, a solubility inhibiting agent, or a combination thereof A further embodiment of this invention is a lithographic pπnting plate comprising a support and an imaging layer consisting essentially of ( 1 ) a second polymer selected from the group consisting of a novolac resin, a butylated thermosettmg phenolic resm, poly(vιnyl phenol-co-2-hydroxyethyl methacrylate), and a co-polymer based on methacrylamide, acrylomtπle, methylmethacrylate, and the reaction product of methacryloxyethyhsocyanate with aminophenol, (2) a napthoqumone diazide polymer which is a condensation polymer of pyrogallol and acetone having a plurality of pendent 1,2-napthoquιnone diazide groups bonded to the condensation polymer through a sulfonyl ester linkage, (3) an infrared absorbing compound, and optionally, (4) a visible absoφtion dye, an lodomum salt, or a combination thereof DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method for directly imagmg a lithographic pπnting surface usmg infrared radiation without the requirement of pre- or post- UV- ght exposure, or heat treatment This method employs a pπntmg plate which compπses a support with a hydrophihc surface and an imaging layer coated over that hydrophihc surface The imaging layer contains at least one polymer having a plurality of pendent groups bonded thereto which are selected from the group consisting of hydroxy, carboxylic acid, tert-butyl-oxycarbonyl, sulfonamide, amide, nitnle, urea, and combinations thereof, and an infrared absorbing compound The imagmg layer may contain a second polymer which has a plurality of pendent groups bonded thereto which are selected from the group consisting of 1,2-napthoquιnone diazide, hydroxy, carboxylic acid, sulfonamide, hydroxymethyl amide, alkoxymethyl amide, nitnle, maleimide, urea, and combinations thereof The lmaging layer also contain a visible absoφtion dye, a solubility inhibiting agent, or a combination thereof In the method of this invention, the imaging layer is imagewise exposed to infrared radiation to produce exposed image areas m the imaged layer These exposed image areas have the unusual charactenstic of transient solubility m an aqueous alkaline developing solution so that solubility is gradually lost over a period of time until the imaged areas become as insoluble as non-imaged areas Consequently, the imaged layer is contacted with an aqueous alkaline developing solution within a time period of 20 hours or less of the imaging exposure, and preferably within about 120 minutes of exposure Development with the developing solution removes the exposed image areas from the hydrophihc surface to form the lithographic pπnting surface compπsed of unexposed image areas and complimentary uncovered areas of the hydrophihc surface In this method, the infrared radiation preferably is laser radiation and is digitally controlled Lithographic Printing Plate The lithographic pπnting plate used in the method of this invention, comprises a support which has a hydrophihc surface, and an imagmg layer which is coated over the hydrophihc surface The imaging layer contains at least one polymer having a plurality of pendent groups bonded thereto which are selected from the group consisting of 1,2-napthoquιnone diazide, hydroxy, carboxylic acid, tert-butyl-oxycarbonyl, sulfonamide, hydroxymethyl amide, alkoxymethyl amide, urea, and combinations thereof, and an infrared absorbing compound The imaging la er may contain a second polymer having reactive pendent groups selected from the group consistmg of hydroxy, carboxylic acid, tert -butyloxycarbonyl, sulfonamide, hydroxymethyl amide, and alkoxymethyl amide The imaging layer may also contain a visible absorbing dye to provide a contrast image to the undeveloped layer, as well as a solubility inhibiting agent to reduce the solubility of unexposed areas of the layer The imaging layer contains at least one polymer having a plurality of pendent groups bonded thereto which are selected from the group consisting of hydroxy, carboxylic acid, sulfonamide, amide, nitnle, urea, and combinations thereof, and an infrared absorbing compound and may contain a second different polymer of the same class to provide supplementary properties to the imaging layer The polymer may be a condensation polymer such as phenolic resins, or it may be a free radical addition polymer such as acrylics, vinyl polymers and the like The term " " hydroxy" as used herein is intended to include both aryl hydroxy and alkyl hydroxy groups Preferred polymers for use in the imaging layer either individually or m combination include phenolic polymers such as butylated thermoseting phenolic resin, novolac resins such as novolac PD-140A (a product of Borden Chemical, MA), and the like, acrylic polymers such as poly(vιnyl phenol-co-2- hydroxyethyl methacrylate) Preferred condensation polymers, are condensation polymers of phenolic compounds with carbonyl compounds Suitable phenolic compounds mclude phenol, chatechol, pyrogallol, alkylated phenols such as cresols, alkoxylated phenols and the like Suitable carbonyl compounds mclude formaldehyde, acetone, and the like Such condensation polymers mclude novolac resins and resole resins which are condensation products of the phenolic compounds with formaldehyde Useful free radical addition polymers include poly(4-hydroxystyrenc), poly(4- hydroxystyrene/methyl-methacrylate), poly(styrene/ butylmethacrylate/methylmethacrylate/ methacry c acid), poly(butyl-methacrylate/methacryhc acid), poly(vιnylphenol/2-hydroxyethyl- methacrylate), poh (styrene/n-butyl-methacrylate/2-hydroxyeth}'l-methacrylate/methacryhc acid), poly(N-methoxymethyl-methylacrylamιde/2-phenylethylmethacrylate/ methacryhc acid), pol> late/methacr ~ > e acid), aciy e and vinyl polymers containing a plurality of pendent 1 ,2-napthoquιnone diazide groups, and the like The imagmg layer may contain a second polymer to supplement properties imparted by the first polymer The second polymer has a plurality of pendent groups bonded thereto which are selected from the group consistmg of 1,2-napthoquιnone diazide, hydroxy. carboxylic acid, sulfonamide, hydroxymethyl amide, alkoxymethyl amide, mtnle, maleimide, urea, and combinations thereof Many embodiments of the second polymer are the same embodiments as descπbed supra in reference to the first polymer However, several distinct embodiments are possible m the second polymer, most notably with the presence of pendent 1 ,2-napthoquιnone diazide groups 1,2- napthoquinone diazide polymers preferably are condensation phenolic polymers having a plurality of pendent 1,2-napthoqumone diazide groups bonded to the condensation polymer through a sulfonyl ester linkage Prefened condensation polymers, are condensation polymers of phenolic compounds with carbonyl compounds Suitable phenolic compounds include phenol, chatechol, pyrogallol, alkylated phenols such as cresols, alkoxylated phenols and the like Suitable carbonyl compounds mclude formaldehyde, acetone, and the like Such condensation polymers mclude novolac resins and resole resins which are condensation products of the phenolic compounds with formaldehyde Suitable 1,2-napthoquιnone diazide polymers are polymers, particularly phenolic condensation polymers, which have a plurality of pendent 1,2-napthoquιnone diazide groups bonded to the polymer along with a plurality of hydroxy groups Particularly useful polymers in formulating the napthoqumone diazide polymer, are condensation polymers of a phenolic compound with a carbonyl compound as described supra The pendent 1,2-napthoqumone diazide groups typically are bonded to the phenolic polymer through an ester linkage particularly through a sulfonyl ester linkage Suitable 1,2-napthoqumone diazide polymers of this type include those disclosed in U S Patent 3,635,709 A particularly prefened 1 ,2-napthoquιnone diazide polymer disclosed in example 1 of this patent, is the condensation polymer of pyrogallol and acetone having a plurality of pendent 1,2- napthoqumone diazide groups bonded to the condensation polymer through a sulfonyl ester linkage The imaging layer of this invention also requires, as a component, an infrared absorber to render the layer sensitive to infrared radiation and cause the printing plate to be imageable by exposure to a laser source emitting m the infrared region The infrared absorbing compound may be a dye and/or pigment, typically having a strong absoφtion band in the region between 700 nm and 1400 nm, and preferably in the region between 780 nm and 1300 nm A wide range of such compounds is well known m the art and mclude dyes and/or pigments selected from the group consisting of tnarylamine dyes, thiazohum dyes, indolium dyes, oxazohum dyes, cyamne dyes, polyanihne dyes, polypyrrole dyes, polythiophene dyes, thiolene metal complex dyes, carbon black, and polymeπc phthalocyanme blue pigments Examples of the infrared dyes employed in the imaging layer are Cyasorb IR99 (available from Glendale Protective Technology). Cyasorb IR165 (available from Glendale Protective Technology). Epo te III- 178 (available from Epohne), Epohte IV-62B (available from Epolme), PINA-780 (available from Allied Signal) and SpectraIR830A (available from Spectra Colors Coφ ), SpectraIR840A (available from Spectra Colors Coφ ) The infrared absorber is used in the imaging layer in an amount from about 0 2 to about 30 weight percent, percent and preferably from about 0 5 to about 20 weight percent, based on the weight of the composition An optional indicator dye is typically added to the imaging layer to provide a visual image on the exposed plate pnor to inking or mounting on the press Suitable indicator dyes for this puφose mclude Basic Blue 1, 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, Ethyl Violet, and Solvent Blue 36 Preferably the imaging layer contams an mώcator 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 A solubility inhibiting agent may be added to the imaging layer to reduce the solubility of unexposed areas of the layer m a developer solution for the imaged plate Useful solubility inhibiting agents include cationic onium salts such as lodomum salts, ammonium salts, sulfonmm salts and the like Prefened agents of this class mclude diaryhodonium salts such as 2-hydroxy- tetradecyloxyphenyl-pheny odonium hexafluoroantimonate (available as CD1012 from Sartomer Company, Exton, PA), qumolmium and isoqumolimum salts such as N-benzyl qumohnium bromide, tπarylsulfonium salts, and the like The compositions for use in this invention may be readily coated on a smooth or grained- surface aluminum substrate to provide pnntmg plates especially useful for lithographic pπnting process However, polymeric or paper sheet substrates may likewise be used provided the sheet substrate has a hydrophihc surface Such polymenc substrates mclude dimensionally stable sheets of polyethylene terephthalate, polycarbonate and the like To form pnnt g plates of this invention , the compositions typically may be dissolved in an appropπate solvent or solvent mixture, to the extent of about 5 to 15 weight percent based on the weight of the composition Appropnate solvents or solvent mixtures include methyl ethyl ketone, methyl isobutyl ketone, 2-ethoxyethanol, 2 butoxyethanol, methanol, isobutyl acetate, methyl lactate, etc Desirably , the coating solution will also contain a typical silicone-tjpe flow control agent The sheet substrate, typically aluminum, 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 dned with the aid of an airstream having a temperature from about 60 to about 100°C for about 0 5 to 10 minutes The resulting plate will have an imaging layer having a thickness preferably between about 0 5 and about 3 micrometers A preferred lithographic pnntmg plate of this invention compnses a support and an imagmg layer consisting essentially of a phenolic polymer having a plurality of pendent groups bonded thereto wherein the pendent groups are selected from the group consisting of hydroxy, carboxylic acid, sulfonamide, amide, nitnle, urea, and combinations thereof, an infrared absorbing compound, and optionall} , a visible absoφtion dye, a solubility inhibiting agent, or a combination thereof An equally prefened lithographic pnnting plate of this invention compnses a support and an imaging layer consisting essentially of a napthoqumone diazide polymer which is a condensation polymer of pyrogallol and acetone having a plurality of pendent 1,2-napthoquιnone diazide groups bonded to the condensation polymer through a sulfonyl ester linkage, a polymer selected from the group consisting of a novolac resm, a butylated thermosettrng phenolic resm, poly(vιnyl phenol-co-2- hydroxyethyl methacrylate), and a co-polymer based on methacrylamide, acrylomtnle, methylmethacrylate, and the reaction product of methacryloxyethylisocyanate with aminophenol, an infrared absorbing compound, and optionally, a visible absoφtion dye, a solubility inhibiting agent, or a combination thereof In each of these embodiments the solubility inhibiting agent when present, preferably is an lodonium salt or an ammonium salt Preparation of a Lithographic Printing Surface In the method of this invention, a lithographic printing surface is prepared using a lithographic printing plate as descnbed supra The lithographic pnntmg plates of this mvention are imagewise exposed by a radiation source that emits m the infrared region, I e , between about 700 nm and about 1,400 nm Preferably, the infrared radiation is laser radiation Such laser radiation may be digitally controlled to imagewise expose the imaging layer In this context, the lithographic pnnting plates of this invention are uniquely adapted for direct-to-plate" imaging Direct-to-plate systems utilize digitized information, as stored on a computer disk or computer tape, which is intended to be printed The bits of information in a digitized record corcespond to the image elements or pixels of the image to be pnnted 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, in turn, may be controlled by a rotating drum, a leadscrew, or a turning mirror The exposure beam is then turned off in correspondence with the pixels to be pnnted The exposing beam is focused onto the imaging layer of the unexposed plate During 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 indicator d>e is present in the imaging layer a visible image is likewise produced on the surface of the plate During imaging exposure, exposed areas of the imaging layer are solubihzed and can be removed with an alkaline developing solution Suφπsingly, this solubility of exposed image areas solubility is gradually lost over a penod of time until the exposed areas become difficult to develop resulting in ink pick up or tonmg duπng pnntmg Smce developability of the exposed image areas is transient, the imaged layer should be contacted with an aqueous alkaline developmg solution within the transient time penod, typically 20 hours or less of the imagmg exposure, and preferably within about 120 minutes of exposure Most preferably, the imaged lithographic plate is developed immediately after the imaging exposure The imaged lithographic pnnting plate of this invention is either hand developed or machine developed within the transient time period using conventional aqueous, alkaline developing solutions Useful aqueous alkaline developers containing an amphoteπc surfactant are disclosed in U S Patent 3,891,439 Prefened aqueous developing solutions are commercially available and include Polychrome® PC-952, Polychrome® PC-9000, Polychrome® PC3955, Polychrome® 4005, Polychrome® 3000, and the like (Polychrome is a registered trademark of the Polychrome Coφoration, Fort Lee, NJ ) After development with the aqueous alkaline developing solution the printing plate typically is treated with a conventional finisher such as gum arable The positive lithographic plates of this invention and their method of use will now be illustrated by the following examples but is not intended to be limited thereby Example 1 The polymenc coating solution was prepared by dissolving 1 0 g 1 ,2-napthoquιnone diazide polymer which is a condensation polymer of pyrogallol and acetone, and the 1,2-napthoquιnone diazide groups are bonded to the phenolic polymer through a sulfonyl ester linkage (hereinafter P3000, available from Polychrome), 0 6 g butylated, thermosetmg phenolic resin (GPRI-7550, available from Georgia Pacific), 0 3 g Epohte III- 178 infrared absorbing dye (available from Epohn, Inc , Newark, NJ) and 0 02 g Victoπa Blue BO into 30 g solvent mixture containing 22% methyl ethyl ketone, 33% methyl isobutyl ketone, 22% ethyl cellosolve, 33% isobutyl acetate and a trace amount of FC430 surfactant The solution was spin coated on the EG-alummum substrate at 85 φm and dned at 60° C for 3 minutes to produce a uniform polymenc coating having a coating weight between 1 0 and 1 5 g/m 2 The plate was imaged on the Gerber Crescent 42T thermal plate setter, which is equipped with a YAG laser having a wavelength at around 1064 nm, at an energy density between 200 and 400 mJ/cm 2 The plate was then developed immediately after exposure with Polychrome aqueous developer PC-9000 to produce a high resolution pnntmg image EXAMPLE 2 The polymenc coating solution was prepared similar to example 1, except that Epohte 62B infrared absorbmg dye (available from Epolm, Inc , Newark, NJ) was used to replace Epohte III- 178 The solution was spin coated on the EG-aluminum substrate at 85 φm and dned at 60° C for 3 minutes to produce a uniform polymenc coating having a coating weight between 1 0 and 1 5 g/m 2 The plate was imaged on the Creo-Trendsetter thermal plate setter, which is equipped with diode lasers having a wavelength at around 830 nm, at an energy density between 200 and 400 mJ/cm 2 The plate was then developed immediately with Polychrome aqueous developer PC-9000 to produce a high resolution pnnting image EXAMPLE 3 The polymenc coating solution was prepared similar to Example 1 , except that 0 6 g Resyn 28-2930 carboxylated vinyl acetate teφolymer ( a product of National Starch and Chemical Coφ ) was used to replace the GPRI-7550 phenolic resin The solution was spin coated on the EG- aluminum substrate at 85 φm and dned at 60 ° C for 3 minutes to produce a uniform polymenc coating having a coating weight between 1 0 and 1 5 g/m 2 The plate was imaged on the Gerber Crescent 42T thermal plate setter, which is equipped with a YAG laser having a wavelength at around 1064 nm, at an energy' density between 200 and 400 mJ/cm 2 The plate was then developed immediately with Polychrome aqueous developer PC- 9000 to produce a high resolution pnntmg image EXAMPLE 4 The polymenc coating solution was prepared similar to Example 1. except that 0 6 g poly(vmylphenol-co-2-hydroxyethylmethacrylate) was used to replace GPR1-7550 resin The solution was spin coated on the EG-alummum substrate at 85 φm and dried at 60 ° C for 3 minutes to produce a uniform polymenc coatmg having a coating weight between 1 0 and 1 5 g/m 2 The plate was imaged on the Gerber Crescent 42T thermal plate setter, which is equipped with a YAG laser having a wavelength at around 1064 nm, at an energy density between 200 and 400 mJ/cm 2 The plate was then developed immediately with Polychrome aqueous developer PC- 9000 to produce a high resolution pnnting image EXAMPLE 5 The polymenc coating solution was prepared by dissolving 3 0 g P3000 polymer of Example 1, 1 0 g GPRI-7550 phenolic resm, 3 0 g Resyn 28-2930, 0 9 g Epohte III-178 infrared dye and 0 05 g Victoπa Blue BO into 30 g solvent mixture containmg 22% methyl ethyl ketone, 33% methyl isobutyl ketone, 22% ethyl cellosolve, 33% isobutyl acetate and a trace amount of FC430 surfactant The solution was spin coated on the EG-alummum substrate at 85 φm and dned at 60 ° C for 3 minutes to produce a uniform polymenc coating having a coatmg weight between 1 0 and 1 5 g/m 2 The plate was imaged on the Gerber Crescent 42T thermal plate setter, which is equipped with a YAG laser having a wavelength at around 1064 nm, at an energy density between 200 and 400 mJ/cm 2 The plate was then developed immediately with Polychrome aqueous developer PC- 9000 to produce a high resolution pnnting image EXAMPLE 6 The polymenc coating solution was prepared by dissolving 0 4 g P3000 polymer, 5 6 g SD140A novolac phenolic resin (available from Borden Chemicals, MA). 0 8 g 2-hydroxy- tetradecyloxyphenyl-pheny odonium hexafluoroantimonate (hereinafter CD1012 available from Sartomer). 0 6 g SpectraIR830A infrared dye (available from Spectra Colors Coφ ) and 0 2 g Solvent Blue 35 mto 80 g solvent mixture containing 22% methyl ethyl ketone, 33% methyl isobutyl ketone, 22% ethyl cellosolve, 33% isobutyl acetate and a trace amount of FC430 surfactant The solution was spin coated on the EG-alummum substrate at 85 φm and dned at 60 ° C for 4 minutes to produce a uniform polymenc coating having a coating weight between 1 0 and 1 5 g/m 2 The plate was imaged on the Creo-Trendsetter thermal plate setter, which is equipped with multiple diode laser beam having a wavelength at around 830 nm, at an energy density between 160 and 400 mJ/cm 2 The plate was then developed immediately with Polychrome aqueous developer PC3955 to produce a high resolution pnnting image Example 7 A polymenc coating solution was prepared by dissolving 6 0 g SD140A novolac resin, 0 8 g 2-hydroxytetradecyloxyphenylphenyhodonιum hexafluoroantimonate (CD 1012), 0 6 g SpectralR830A infrared dye (available from Spectra Colors Coφ ) and 0 2 g Solvent Blue 35 into 80 g solvent mixture containing 22% methyl ethyl ketone, 33% methyl isobutyl ketone. 22% ethyl cellosolve, 33% isobutyl acetate and a trace amount of FC430 surfactant The solution was spin coated on the EG-alummum substrate at 85 φm and dried at 60 ° C for 4 minutes to produce a uniform polymenc coatmg having a coatmg weight between 1 0 and 1 5 g/m 2 The plate was imaged on the Creo-Trendsetter thermal plate setter, which is equipped with multiple diode laser beam having a wavelength at around 830 nm, at an energy density between 160 and 400 mJ/cm 2 The plate was then developed immediately with Polychrome aqueous developer CI 10 to produce a high resolution pnnting image Example 8 A polymenc coatmg was prepared by dissolving 0 4 g ADS 1060A IR near infrared absorbing dye (available from ADS Canada), 0 05 g ethyl violet, 0 6 g Uravar FN6 resole phenolic resin (available from DSM, Netherlands), 1 5 g PMP-92 co-polymer (PMP-92 co-polymer is based on methacrylamide, N-phenyl-maleimide. and APK which is methacryloxyethyhsocyanate reacted with aminophenol (available from Polychrome Coφoration), and 7 45 g PD140A novolac resm (available from Borden Chemicals, MA) into 100 g solvent mixture containing 15% Dowanol PM, 40% 1,3-dιoxolane and 45% methanol The solution was coated with a wire wound bar onto an EG-alummum substrate and dned at 100°C for 5 mmutes to produce a uniform polymeric coatmg having a coatmg weight of 1 8 to 2 2 g/m 2 The plate was imaged on a Gerber Crescent 42T thermal plate setter, which is equipped with a YAG laser producing radiation with a wavelength at about 1064 nm, and an energy density between 200 and 400 mJ/cm 2 usmg a UGRA/FOGRA Postscπpt Control Stnp version 1 1EPS The plate was then immediately developed using Polychrome® 3000 aqueous developer to produce a high resolution pπnting image The plate was then gummed with Polychrome® 850S standard gum and put on a Roland Favont press to produce 70,000 good pπnts Example 9 A polymeric coatmg was prepared by dissolvmg 0 2 g SpectraIR830 dye (available from Spectra Colors Coφ . Kearny, NJ). 0 05 g ethyl violet, 0 6 g Uravar FN6 resole resm, 1 5 g PMP- 65 co-polymer (PMP-65 co-polymer is based on methacrylamide, acrylonitπle. methylmethacrylate, and APK which is methacryloxyethyhsocyanate reacted with aminophenol (available from Polychrome Coφoration), and 7 65 g PD140A novolac resin, into 100 g solvent mixture containing 15% Dowanol PM, 40% 1,3-dιoxolane and 45% methanol The solution was coated with a wire wound bar onto an EG-alummum substrate and dned at 100°C for 5 minutes to produce a uniform polymenc coating having a coating weight of 1 8 to 2 2 g/m 2 The plate was imaged on a Creo-Trendsetter thermal plate setter, which is equipped with multiple diode laser beams producing radiation with a wavelength at about 830 nm, and an energy density between 160 and 400 mJ/cm 2 usmg a UGRA FOGRA Postscnpt Control Stnp version 1 1 EPS The plate is then immediately developed using Polychrome® 3000 aqueous developer to produce a high resolution printing image Example 10 A polymenc coatmg was prepared by dissolving 8 7 g PD140A novolac resm, 0 8 g ST 798 infrared dye (available from Syntec, Germany), 0 5 g N-benzyl quinohmum bromide into 100 ml solvent mixture containing 30 ml methyl glycol, 25 ml methyl ethyl ketone, and 45 ml methanol The solution was coated with a wire wound bar onto an EG, anodized and PVPA rnterlayered aluminum substrate and dned at 90°C for 5 mmutes to produce a uniform polymenc coatmg hav g a coatmg weight of 2 0 g/m 2 The plate was imaged on a Creo-Trendsetter thermal plate setter, which is equipped with multiple diode laser beams producing radiation with a wavelength at about 830 nm, and an energy density between 160 and 400 mJ/cm 2 usmg a UGRA/FOGRA Postscnpt Control Stnp version 1 1EPS The plate is then immediately developed using Polychrome® 4005 aqueous developer to produce a high resolution pnntmg image Example 1 1 A polymeric coating was prepared by dissolving 7 5 g PD140A novolac resin, 1 3 g PMP- 92 co-polymer, 0 6 g P3000 1 ,2-napthoquιnone diazide polymer. 0 3 g Ethyl Violet, 0 4 g SpectraIR830 dye and 0 2 g CAP 482-05 cellulose acetate phthalate (available from Eastman Chemical Co , Kingsport, TN) , into 100 g solvent mixture containing 15% Dowanol PM, 40% 1,3- dioxolane and 45% methanol The solution was coated with a wire wound bar onto an EG, anodized and PVPA mterlayered aluminum substrate and dried at 90°C for 5 minutes to produce a uniform polymenc coatmg havmg a coatmg weight of 2 0 g/m 2 The plate was imaged on a Creo-Trendsetter thermal plate setter, which is equipped with multiple diode laser beams producing radiation with a wavelength at about 830 nm, and an energy density between 160 and 400 mJ/cm 2 usmg a UGRA FOGRA Postscnpt Control Strip version 1 1EPS The plate is then immediately developed using Polychrome® 2000M aqueous developer to produce a high resolution pnnting image Example 12 A polymeric coating was prepared by dissolving 8 9 g PD140A novolac resin, 1 5 g PMP- 92 co-polymer, 0 3 g Ethyl Violet, and 5 7 g ADS 1 60A IR dye, into 100 g solvent mixture containing 15% Dowanol PM, 40% 1,3-dιoxolane and 45% methanol The solution was coated with a wire wound bar onto an EG, anodized and PVPA mterlayered aluminum substrate and dried at 90°C for 5 mmutes to produce a uniform polymenc coatmg having a coat g weight of 2 0 g/m 2 The plate was imaged on a Gerber Crescent 42T thermal plate setter, which is equipped with a YAG laser producmg radiation with a wavelength at about 1064 nm, and an energy density between 200 and 400 mJ/cm 2 using a UGRA FOGRA Postscnpt Control Stnp version 1 1EPS The plate is then immediately developed using Polychrome® 2000M aqueous developer to produce a high resolution pnnting image Comparative Example A A polymenc coating solution was prepared and coated on the EG-aluminum substrate as descπbed m Example 7 to produce a uniform polymenc coatmg having a coating weight between 1 0 and 1 5 g/m 2 The plate was imaged on the Creo-Trendsetter thermal plate setter, which is equipped with multiple diode laser beam havmg a wavelength at around 830 nm, at an energy density between 160 and 400 mJ/cm 2 The imaged plate was then passed through an oven at 125°C and at a rate of 2 5 ft /nun (a residence time of about 1 5 minutes) and then cooled to room temperature The heat- cycled plate was then immediately developed with Polychrome aqueous developer C 110 Both the exposed and the unexposed areas of the imaged, heat-cycled plate were washed from the aluminum substrate Comparative Example B A polymenc coating solution was prepared and coated on the EG-aluminum substrate as descnbed in Example 7 to produce a uniform polymeric coating having a coating weight between 1 0 and 1 5 g/m 2 The plate was imaged on the Creo-Trendsetter thermal plate setter, which is equipped with multiple diode laser beam having a wavelength at around 830 nm, at an energy density between 160 and 400 mJ/cm The plate was allowed to stand at room temperature for 24 hours before development The plate was then developed with Pol chrome aqueous developer CI 10 to produce a high resolution pnntmg image However, the developed, exposed areas are slightly stammg and pick up ink when run on press indicating incomplete development of exposed areas Comparative Example C A polymenc coating solution was prepared and coated on the EG-alummum substrate as descnbed in Example 7 to produce a uniform polymenc coatmg having a coating weight between 1 0 and 1 5 g/m 2 The plate was imaged on the Creo-Trendsetter thermal plate setter, which is equipped with multiple diode laser beam havmg a wavelength at around 830 nm, at an energy density between 160 and 400 mJ/cm 2 The plate was then heated in an oven at 60°C for 5 mmutes and then was allowed to stand at room temperature for 5 hours before development The plate was then developed with Polychrome aqueous developer C 11 to produce a high resolution pnnting image However, the developed, exposed areas are slightly stammg and pick up ink when run on press indicating mcomplete development of exposed areas 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 mvention as set forth in the appended claims

Claims: What is claimed is 1 A method for forming a lithographic pnnting surface consisting essentially of the following steps earned out in the order given (a) providing a lithographic pnnting plate compnsing a support having a hydrophihc surface and an imaging layer applied to the hydrophihc surface, the imaging layer comprising, (1) a polymer havmg a plurality of pendent groups bonded thereto wherein the pendent groups are selected from the group consisting of hydroxy, carboxylic acid, sulfonamide, amide, nitnle, urea, and combinations thereof, and (2) an infrared absorbing compound, (b) imagwise exposing the imaging layer to infrared radiation to produce exposed image areas which have transient solubility m an aqueous alkaline developing solution, and, (c) contacting the imaging layer with the aqueous alkaline developing solution to remove the exposed image areas from the hydrophihc surface to form the lithographic printing surface compπsed of unexposed image areas 2 The method of claim 1 wherein the imaging layer is contacted with the aqueous alkaline developing solution within a time penod of 20 hours from the imagewise exposing of the imaging layer 3 The method of claim 1 wherein the the imaging layer is contacted with the aqueous alkaline developmg solution within a time penod of 120 minutes from the imagewise exposing of the imaging layer 4 The method of claim 1 wherein the imaging layer is contacted with the aqueous alkaline developmg solution immediately after imagewise exposing of the imaging layer 5 The method of claim 1 wherem the infrared radiation is laser radiation 6 The method of claim 5 wherein the laser radiation is digitally controlled to imagewise expose the imaging layer 7 The method of claim 1 wherem the polymer is a phenolic polymer 8 The method of claim 1 wherein the polymer is an acrylic or vinyl polymer selected from the group consisting of poly( vinyl phenol-co-2-hydroxyethyl methacrylate), poly(4-hydroxystyrene), poly(4-hy droxy -sty rene/methylmethacrylate), poly(styrene/ buty lmethacrylate/methylmethacrylate/ methacryhc acid). poly(butylmethacrylate/methacrylιc acid), poly(vιnylphenol/2-hydroxyethyl- methacrylate), poly(styrene/n-butyl-methacrylate/2-hydroxyethyl methacrylate/methacrylic acid), poly(N-methoxymethylmethylacrylamιde/2-phenylethylmethacrylate/ methacryhc acid), and poly(styrene/ethyl-methacrylate/2-hydroxyethylmethacrylate/ methacryhc acid) 9 The method of claim 1 wherem the imaging layer contains a second polymer having a plurality of pendent groups bonded thereto wherein the pendent groups are selected from the group consisting of 1,2-napthoqumone diazide, hydroxy, carboxylic acid, sulfonamide, amide, nitnle, urea, and combinations thereof 10 The method of claim 9 wherem the second polymer is a phenolic polymer and the phenolic polymer has a plurality of pendent 1.2-napthoquιnone diazide groups bonded thereto 1 1 The method of claim 10 wherein the second polymer is a condensation polymer of pyrogallol and acetone, and the 1,2-napthoqumone diazide groups are bonded to the phenolic polymer through a sulfonyl ester linkage 12 The method of claim 1 wherein the infrared absorbing compound is a dye and/or pigment having a strong absoφtion band m the region between 700 nm and 1400 nm 13 The method of claim 1 wherem the infrared absorbing compound is selected from the group consisting of tnarylamine dyes, thiazohum dyes, indolium dyes, oxazohum dyes, cyanine dyes, polyamhne dyes, polypyrrole dyes, polythiophene dyes, thiolene metal complex dyes, carbon black, and polymenc phthalocyanine blue pigments 14 The method of claim 1 wherem the imagmg layer contains a visible absorbing dye 15 The method of claim 14 wherem the visible absorbmg dye is selected from the group consisting of Victoπa Blue R, Victoπa Blue BO, Solvent Blue 35, Ethyl Violet, and Solvent Blue 36 16 The method of claim 1 wherein the imaging layer contams a solubility inhibiting agent 17 The method of claim 16 wherem the solubility inhibiting agent is an lodonium salt 18 The method of claim 16 wherem the solubility inhibiting agent is an ammonium salt 19 The method of claim 1 wherein the support is an alummum substrate 20 The method of claim 1 wherein the aqueous alkaline developmg solution contains an amphotenc surfactant 21 A lithographic pnntmg plate compnsing a support and an imaging layer consisting essentially of ( 1 ) a polymer having a plurality of pendent groups bonded thereto wherein the pendent groups are selected from the group consisting of hydroxy. carboxylic acid, sulfonamide, amide, nitnle. urea, and combinations thereof, (2) an infrared absorbing compound, and optionally, (3) a visible absoφtion dye, a solubility inhibiting agent, or a combination thereof 22 The lithographic pnnting plate of claim 21 wherein the polymer is a phenolic polymer 23 The lithographic pnnting plate of claim 21 wherein the solubility inhibiting agent is an lodonium salt or an ammonium salt 24 A lithographic pnntmg plate compnsing a support and an imaging layer consisting essentially of ( 1 ) a polymer selected from the group consisting of a novolac resm, a butylated thermosettmg phenolic resm, poly(vιnyl phenol-co-2-hydroxyethyl methacrylate), and a co-polymer based on methacrylamide, acrylomtnle, methylmethacrylate, and the reaction product of methacryloxyeth hsocyanate with aminophenol, (2) a napthoquinone diazide polymer which is a condensation polymer of pyrogallol and acetone having a plurality of pendent 1,2-napthoquιnone diazide groups bonded to the condensation polymer through a sulfonyl ester linkage, (3) an infrared absorbmg compound, and optionally, (4) a visible absoφtion dye. an lodonium salt, or a combination thereof

Inventors: HALLMAN ROBERT W, HAUCK GERHARD, KESSELMAN JEROME P, MERCHANT NISHITH, NGUYEN MY T, PAPPAS PETER S, SAVARIAR-HAUCK CELIN, SHIMAZU KEN-ICHI, TIMPE HANS-JOACHIM, HALLMAN, ROBERT, W., HAUCK, GERHARD, KESSELMAN, JEROME, P., MERCHANT, NISHITH, NGUYEN, MY, T., PAPPAS, PETER, S., SAVARIAR-HAUCK, CELIN, SHIMAZU, KEN-ICHI, TIMPE, HANS-JOACHIM
Applicants: KODAK POLYCHROME GRAPHICS LLC
Application year: 1998
Main classification: B41C1
IPC codes: B41C1, B41M5