INFRARED RADIATION SENSITIVE POSITIVE-WORKING IMAGEABLE ELEMENT AND METHOD FOR FORMING IMAGE USING SAME

Abstract

Disclosed is a infrared radiation sensitive positive-working imageable element. The imageable element comprises: (a) a substrate, (b) an inner coating covering the substrate, and (c) an outer coating covering the inner coating. The inner coating comprises a repeating unit derived from a maleimide monomer and a (meth)acrylamide monomer, and a polymer hinder P that is soluble in an alkaline developing solution; and the outer coating comprises an infrared radiation absorbing compound and a polymer binder Q which is different from that in the inner coating. The imageable element is designed such that same is not only sensitive to radiation with a maximum wavelength of 700-1200 nm, but also has a good resistance to chemical solvents when used as a lithographic printing plate precursor, and same is not easily corroded and dissolved by printing chemicals during use, thus facilitating the prolonging of the service life of a lithographic printing plate.

Claims

1. An infrared radiation-sensitive positive-working imageable element, comprising: (a) a substrate; (b) an inner coating covering the substrate, the inner coating comprises a polymer binder P, which comprises at least two repeating units of a maleimide monomer and a (meth)acrylamide monomer and is soluble in an alkaline developing solution; and (c) an outer coating covering the inner coating, the outer coating comprises an infrared radiation absorbing compound and a polymer binder Q which is different from the polymer binder Pinner coating.

2. The infrared radiation-sensitive positive-working imageable element of claim 1, wherein the polymer binder P comprised in the inner coating can be represented by the following structural formula (I):
—(A).sub.x-(B).sub.y-(C).sub.z—  (I) A represents a repeating unit derived from one or more maleimide monomers ##STR00006## wherein R can be optionally substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, hydroxyl, substituted or unsubstituted alkoxy; B represents a repeating unit derived from one or more (meth)acrylamide monomers ##STR00007## wherein R.sub.1 can be optionally hydrogen, substituted or unsubstituted alkyl, substituted or unsubstituted cycloalkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, hydroxyl, substituted or unsubstituted alkoxy; R.sub.2 can be optionally hydrogen or methyl; C represents a repeating unit derived from one or more other ethylenically unsaturated polymerizable monomers different from A and B; wherein, based on x+y+z=100% of a total weight of the polymer binder P having a structural formula (I), wherein x is 1 to 85 wt %, y is 1 to 80 wt %, and z is 1 to 80 wt %, or any combination thereof.

3. The infrared radiation-sensitive positive-working imageable element of claim 1, wherein the polymer binder P is 40-99.9wt % of the total weight of the inner coating.

4. The infrared radiation-sensitive positive-working imageable element of claim 1, wherein, the inner coating further comprises a background contrast dye, and the background contrast dye is a dye with high absorption in the visible light region, and the addition amount of the background contrast dye is 0.1 to 8 wt % of the total weight of the inner coating.

5. The infrared radiation-sensitive positive-working imageable element of claim 4, wherein the background contrast dye is one or a mixture of an oil-soluble dye and/or a basic dye.

6. The infrared radiation-sensitive positive-working imageable element of claim 1, wherein the inner coating further comprises an infrared radiation absorbing compound having a wavelength absorption range of 700 to1200 nm, and the addition amount of the infrared radiation absorbing compound is 0.1 to 10 wt % of the total weight of the inner coating.

7. The infrared radiation-sensitive positive-working imageable element of claim 6, wherein the infrared radiation absorbing compound is one or more of a cyanine dye, an anthraquinone dye, a phthalocyanine dye, a quinonimine dye or a methine cyanine dye.

8. The infrared radiation-sensitive positive-working imageable element of claim 1, wherein the inner coating further comprises an acid generator, and the addition amount of the acid generator is 0.1 to 10 wt % of the total weight of the inner coating.

9. The infrared radiation-sensitive positive-working imageable element of claim 8, wherein the acid generator is one or more of onium salt, triazine, acid anhydride and sulfonic ester.

10. The infrared radiation-sensitive positive-working imageable element of claim 1, wherein the inner coating further comprises a polymer binder P.sub.1, the polymer binder P.sub.1 is selected from one or more of phenolic resin, polystyrene derivative, polyurethane, and a polyacrylic acid (ester) which is different from the polymer binder P, and the addition amount of the polymer binder P.sub.1 is 1 to 40 wt % of the total weight of the inner coating.

11. The infrared radiation-sensitive positive-working imageable element of claim 1, wherein the outer coating comprises an infrared radiation absorbing compound having a wavelength absorption range of 700 to 1200 nm and a polymer binder Q which is different from the polymer binder P, and the addition amount of the infrared radiation absorbing compound is 0.5 to 10 wt % of the total weight of the outer coating; the addition amount of the polymer binder Q is 80 to 99.5 wt % of the total weight of the outer coating.

12. The infrared radiation-sensitive positive-working imageable element of claim 11, wherein the infrared radiation absorbing compound is one or more of a cyanine dye, an anthraquinone dye, a phthalocyanine dye, a quinonimine dye or a methine cyanine dye.

13. The infrared radiation-sensitive positive-working imageable element of claim 11, wherein the polymer binder Q can be derived from one or more of phenolic resin, polystyrene derivative, polyurethane and polyacrylic acid which is different from the inner coating polymer binder P.

14. The infrared radiation-sensitive positive-working imageable element of claim 1, wherein the outer coating further comprises a dissolution inhibitor, wherein the dissolution inhibitor is one or more of a triarylmethane dye, an onium salt, a ketone or an ester compound, and the addition amount of the dissolution inhibitor is 0.1 to 20 wt % of the total weight of the outer coating.

15. The infrared radiation-sensitive positive-working imageable element of claim 1, wherein the outer coating further comprises an acid generator, the acid generator is selected from one or more of onium salt, triazine, acid anhydride, and sulfonate, and the addition amount of the acid generator is 0.2 to 10 wt % of the total weight of the outer coating.

16. The infrared radiation-sensitive positive-working imageable element of claim 1 is a positive-working lithographic printing plate precursor with a hydrophilic substrate, wherein the hydrophilic substrate is an aluminum substrate subjected to electrolytic roughening and anodizing treatment.

17. A method for forming an image, wherein the method comprising: A) performing imagewise exposure of the imageable element of claim 1 with infrared radiation to form an imaged element comprising exposed and unexposed areas, B) contacting the imaged element with an alkaline developer to remove only the exposed area to produce an imaged and developed element.

18. The method for forming an image of claim 17, wherein the imagewise exposure is performed by an infrared laser with a radiation wavelength of 700-1200 nm, and the alkaline developer is an aqueous solution with a pH value of less than 14.

19. A lithographic printing plate obtained from the method of claim 17.

20. The infrared radiation-sensitive positive-working imageable element of claim 2 is a positive-working lithographic printing plate precursor with a hydrophilic substrate, wherein the hydrophilic substrate is an aluminum substrate subjected to electrolytic roughening and anodizing treatment.

Description

DETAILED DESCRIPTION OF EMBODIMENTS

[0077] The technical solutions of the present invention will be described in detail below with reference to specific examples. Obviously, the described examples are part of the embodiments of the present invention, rather than all of the embodiments. Based on the examples of the present invention, all other embodiments obtained by those skilled in the art without creative work shall fall within the protection scope of the present invention. In addition, the technical features involved in different examples of the present invention described below can be combined with each other as long as they do not conflict with each other. The following examples are provided to illustrate the implementation of the present invention and are not intended to limit the present invention in any way.

[0078] The following is a synthesis example of the polymer binder P, which are expressed as polymer binder PB-a, polymer binder PB-b etc. according to the order of the synthesis examples for convenience of distinction.

Synthesis Example A: Synthesis of Polymer Binder PB-a

[0079] 4.0 g of p-hydroxyphenyl acrylamide, 15.5 g of N-p-methylphenyl maleimide, 0.5 g of methacrylic acid, 0.2 g of free radical initiator AIBN and 60 g of ethylene glycol monomethyl ether were added into a 250 ml four-neck round bottom flask equipped with a heating jacket, a temperature controller, a mechanical stirrer, a condenser and a nitrogen inlet and outlet. The reaction mixture was heated to 70° C. under the protection of nitrogen, and then the reaction was stirred at this temperature for 5 h. Further, 0.1 g of AIBN was added therein, the reaction was stirred at 65 to 75° C. under the protection of nitrogen for 15 h. After cooling, the reaction mixture was added dropwise to 400 g of stirring methanol (in which 2 drops of concentrated hydrochloric acid was added). The precipitated solid was collected by suction filtration, and then added into 250 g of cold water and stirred for 15 min. A rude product was collected by suction filtration, dried by spreading out on filter paper overnight, and finally dried in an oven at 45° C. Yield: 13.5 g of yellowish solid was obtained.

Synthesis Example B: Synthesis of Polymer Binder PB-b

[0080] 6.0 g of p-sulfonamidophenyl acrylamide, 13.5 g of N-p-methylphenyl maleimide, 0.5 g of methacrylic acid, 0.2 g of AIBN and 60 g of N,N-dimethylacetamide were added into a 250 ml four-neck round bottom flask equipped with a heating jacket, a temperature controller, a mechanical stirrer, a condenser and a nitrogen inlet and outlet. The reaction mixture was heated to 70° C. under the protection of nitrogen, and then the reaction was stirred at this temperature for 5 h. Further, 0.1 g of AIBN was added therein, the reaction was stirred at 65 to 75° C. under the protection of nitrogen for 15 h. After cooling, the reaction mixture was added dropwise to 400 g of stirring methanol (in which 2 drops of concentrated hydrochloric acid was added). The precipitated solid was collected by suction filtration, and then added into 250 g of cold water and stirred for 15 min. A rude product was collected by suction filtration, dried by spreading out on filter paper overnight, and finally dried in an oven at 45° C. Yield: 16.0 g yellowish solid was obtained.

Synthesis Example C: Synthesis of Polymer Binder PB-c

[0081] 7.5 g of p-sulfonamidophenyl acrylamide, 10.5 g of N-phenylmaleimide, 2 g of methyl methacrylate, 0.2 g of AIBN and 60 g of ethylene glycol monomethyl ether were added to a 250 ml four-neck round bottom flask equipped with a heating jacket, a temperature controller, a mechanical stirrer, a condenser and a nitrogen inlet and outlet. The reaction mixture was heated to 70° C. under the protection of nitrogen, and then the reaction was stirred at this temperature for 5 h. Further, 0.1 g of AIBN was added therein, the reaction was stirred at 65 to 75° C. under the protection of nitrogen for 15 h. After cooling, the reaction mixture was added dropwise to 400 g of stirring methanol (in which 2 drops of concentrated hydrochloric acid was added). The precipitated solid was collected by suction filtration, and then added into 250 g of cold water and stirred for 15 min. A rude product was collected by suction filtration, dried by spreading out on filter paper overnight, and finally dried in an oven at 45° C. Yield: 17.2 g yellowish solid was obtained.

Synthesis Example D: Synthesis of Polymer Binder PB-d

[0082] 4.5 g of p-hydroxyphenylacrylamide, 9 g of N-phenylmaleimide, 11 g of acrylonitrile, 12 g of methyl methacrylate, 3.5 g of methacrylic acid, 0.4 g of AIBN and 120 g of ethylene alcohol monomethyl ether was added to a 250 ml four to neck round bottom flask equipped with a heating jacket, a temperature controller, a mechanical stirrer, a condenser and a nitrogen inlet and outlet. The reaction mixture was heated to 70° C. under the protection of nitrogen, and then the reaction was stirred at this temperature for 5 h. Further, 0.2 g of AIBN was added therein, the reaction was stirred at 65 to 75° C. under the protection of nitrogen for 15 h. After cooling, the reaction mixture was added dropwise to 800 g of stirring water (in which 4 drops of concentrated hydrochloric acid was added). The precipitated solid was collected by suction filtration, and then added into 500 g of cold water and stirred for 15 min. A rude product was collected by suction filtration, dried by spreading out on filter paper overnight, and finally dried in an oven at 45° C. Yield: 37.9 g yellowish solid was obtained.

Synthesis Example E: Synthesis of Polymer Binder PB-e

[0083] 10.0 g of N-p-ethylphenylmaleimide, 4.0 g of p-hydroxyphenyl acrylamide and 110 g of N,N-dimethylacetamide were added to a 250 ml four-neck round bottom flask equipped with a heating jacket, a temperature controller, a mechanical stirrer, a condenser, a constant pressure dropping funnel, and a nitrogen inlet and outlet. The constant pressure dropping funnel is filled with a mixture in which 0.4 g AIBN was dissolved in 10 g N,N-dimethylacetamide, 4.0 g methyl methacrylate, 4.0 g styrene, 4.0 g methacrylic acid, and 14 g acrylonitrile. The mixture in the flask was heated to 70° C. under the protection of nitrogen, and the monomer mixture in the constant pressure funnel was added dropwise to the flask within about 30 min, and the reaction was stirred at this temperature for 5 h. Further, 0.2 g of AIBN was added therein, the reaction was stirred at 65 to 75° C. under the protection of nitrogen for 15 h. After cooling, the reaction mixture was added dropwise to 800 g of stirring water (in which 4 drops of concentrated hydrochloric acid was added). The precipitated solid was collected by suction filtration, and then added into 500 g of cold water and stirred for 15 min. A rude product was collected by suction filtration, dried by spreading out on filter paper overnight, and finally dried in an oven at 45° C. Yield: 40.2 g yellowish solid was obtained.

Synthesis Example F: Synthesis of Polymer Binder PB-f

[0084] 6.2 g of methacrylamide, 11.6 g of N-phenylmaleimide, 2.2 g of methacrylic acid, 0.2 g of AIBN and 60 g of ethylene glycol monomethyl ether were added to a 200 ml four-neck round bottom flask equipped with a heating jacket, a temperature controller, a mechanical stirrer, a condenser and a nitrogen inlet and outlet. The reaction mixture was heated to 70° C. under the protection of nitrogen, and then the reaction was stirred at this temperature for 5 h. Further, 0.1 g of AIBN was added therein, the reaction was stirred at 65 to 75° C. under the protection of nitrogen for 15 h. After cooling, the reaction mixture was added dropwise to 400 g of stirring methanol (in which 2 drops of concentrated hydrochloric acid was added). The precipitated solid was collected by suction filtration, and then added into 250 g of cold water and stirred for 15 min. A rude product was collected by suction filtration, dried by spreading out on filter paper overnight, and finally dried in an oven at 45° C. Yield: 18.7 g yellowish solid was obtained.

Synthesis Example G: Synthesis of Polymer Binder PB-g

[0085] Add 6.0 g of N,N-dimethylacrylamide, 12.8 g of N-p-hydroxyphenyl maleimide, 1.2 g of methacrylic acid, 0.2 g of AIBN and 60 g of ethylene glycol monomethyl ether were added into a 200 ml four-neck round bottom flask equipped with a heating jacket, a temperature controller, a mechanical stirrer, a condenser and a nitrogen inlet and outlet. The reaction mixture was heated to 70° C. under the protection of nitrogen, and then the reaction was stirred at this temperature for 5 h. Further, 0.1 g of AIBN was added therein, the reaction was stirred at 65 to 75° C. under the protection of nitrogen for 15 h. After cooling, the reaction mixture was added dropwise to 400 g of stirring methanol (in which 2 drops of concentrated hydrochloric acid was added). The precipitated solid was collected by suction filtration, and then added into 250 g of cold water and stirred for 15 min. A rude product was collected by suction filtration, dried by spreading out on filter paper overnight, and finally dried in an oven at 45° C. Yield: 17.9 g yellowish solid was obtained.

Synthesis Example H: Synthesis of Polymer Binder PB-h

[0086] 2.2 g of acrylamide, 5.4 g of N-phenylmaleimide, 4.0 g of ethyl methacrylate, 6.2 g of acrylonitrile, 2.2 g of methacrylic acid, 0.2 g of AIBN and 60 g of ethylene glycol monomethyl ether were added into a 200 ml four-neck round bottom flask equipped with a heating jacket, a temperature controller, a mechanical stirrer, a condenser and a nitrogen inlet and outlet. The reaction mixture was heated to 70° C. under the protection of nitrogen, and then the reaction was stirred at this temperature for 5 h. Further, 0.1 g of AIBN was added therein, the reaction was stirred at 65 to 75° C. under the protection of nitrogen for 15 h. After cooling, the reaction mixture was added dropwise to 400 g of stirring methanol (in which 2 drops of concentrated hydrochloric acid was added). The precipitated solid was collected by suction filtration, and then added into 250 g of cold water and stirred for 15 min. A rude product was collected by suction filtration, dried by spreading out on filter paper overnight, and finally dried in an oven at 45° C. Yield: 18.9 g yellowish solid was obtained.

[0087] The following are examples for preparing lithographic printing plate precursors, which are expressed as polymer binder PP-a, polymer binder PP-b . . . etc. in the order of synthesis examples for convenience of distinction.

Imageable Element Example 1: Preparation of the Lithographic Printing Plate Precursor (PP-a)

[0088] (1) Inner coating: 0.50 g of polymer binder PB-a and 0.01 g of background dye victoria blue BO were dissolved in a mixed solvent of 6.5 g of ethylene glycol monoethyl ether, 2.0 g of butanone-2, 0.5 g of butyrolactone and 0.5 g of water. The above-mentioned composition solution was coated on the aluminum plate substrate which has been treated by electrochemical roughening and anodizing using a spin coating method, and then dried in an oven at 145 ° C. for 3 min to obtain the inner coating having a weight of 1.2 g/m.sup.2. The inner coating did not dissolve or fall off significantly after soaking in isopropanol for 1 min, showing its excellent alcohol resistance.

[0089] (2) Outer coating: 0.30 g of phenolic resin PD140A, 0.16 g of phenolic resin LB6564, 0.02 g of infrared absorber IRD-85 and 0.02 g of methyl violet were dissolved in a mixed solvent of 5.8 g of propylene glycol monomethyl ether and 3.8 g of butanone-2. The composition solution was coated on the above-mentioned inner coating using a spin coating method, and then dried in an oven at 145° C. for 3 min to obtain the lithographic printing plate precursor (PP-a) having a total weight of the inner coating and outer coating of approximately 2.1 g/m.sup.2.

[0090] The resulting planography printing plate precursor (PP-a) prepared in this example was subjected to scanning exposure by using 830 nm laser with a drum rotation speed of 220 rpm and a laser power of 12 W on a Kodak 800 Quantum-II type CTP platesetter. The exposed original plate was developed with Konita DV-T developer solution at 25° C. for 30 s. After which, the coating on the exposed area of the resulting lithographic printing plate precursor was completely dissolved, while the coating on the unexposed area remained. The image was clear and the edges were sharp and neat.

Imageable Element Example 2: Preparation of the Lithographic Printing Plate Precursor (PP-b)

[0091] (1) Inner coating: 0.50 g of polymer binder PB-b, 0.005 g of infrared absorber IRD-85, 0.01 g of acid generator WPI-169 and 0.01 g of victoria blue BO were dissolved in a mixed solvent of 6.5 g ethylene glycol monoethyl ether, 2.0 g of butanone-2, 0.5 g of butyrolactone and 0.5 g of water. The above-mentioned composition solution was coated on the aluminum plate substrate which has been treated by electrochemical roughening and anodizing using a spin coating method, and then dried in an oven at 145° C. for 3 min to obtain the inner coating having a weight of 1.2 g/m.sup.2. The inner coating did not dissolve or fall off significantly after soaking in isopropanol for 1 min, showing its excellent alcohol resistance.

[0092] (2) Outer coating: 0.45 g of phenolic resin PD-140A, 0.02 g of infrared absorber IRD-85, 0.01 g of acid generator triazine B and 0.02 g of methyl violet were dissolved in a mixed solvent of 5.8 g propylene glycol monomethyl ether and 3.8 g of butanone-2. The composition solution was coated on the above-mentioned inner coating using a spin coating method, and then dried in an oven at 145° C. for 3 min to obtain the lithographic printing plate precursor (PP-b) with a total weight of the inner coating and outer coating of approximately 2.1 g/m.sup.2.

[0093] The resulting planography printing plate precursor (PP-b) prepared in this example was subjected to scanning exposure by using 830 nm laser with a drum rotation speed of 220 rpm and a laser power of 12 W on a Kodak 800 Quantum-II type CTP platesetter. The exposed original plate was developed with Konita DV-T developer solution diluted with water at 25° C. for 35 s. After which, the coating on the exposed area of the resulting lithographic printing plate precursor was completely dissolved, while the coating on the unexposed area remained. The image was clear and the edges were sharp and neat.

Imageable Element Example 3: Preparation of the Lithographic Printing Plate Precursor (PP-c)

[0094] (1) Inner coating: 0.45 g of polymer binder PB-c, 0.05 g of phenolic resin PD494A and 0.01 g of victoria blue BO were dissolved in a mixed solvent of 4.5 g of ethylene glycol monomethyl ether, 3.5 g of butanone-2, and 1.0 g of butyrolactone and 1.0 g of water. The above-mentioned composition solution was coated on the aluminum plate substrate which has been treated by electrochemical roughening and anodizing using a spin coating method, and then dried in an oven at 145 ° C. for 3 min to obtain the inner coating having a weight of 1.2 g/m.sup.2. The inner coating did not dissolve or fall off significantly after soaking in isopropanol for 1 min, showing its excellent alcohol resistance.

[0095] (2) Outer coating: 0.46 g phenolic resin BTB-225, 0.02 g infrared absorber IRD-67, 0.01 g of acid generator Irgacure 250 and 0.02 g of methyl violet were dissolved in a mixed solvent of 5.8 g of propylene glycol monomethyl ether and 3.8 g of butanone-2. The composition solution was coated on the above-mentioned inner coating using a spin coating method, and then dried in an oven at 145° C. for 3 min to obtain the lithographic printing plate precursor (PP to c) having a total weight of the inner coating and outer coating of approximately 2.1 g/m.sup.2.

[0096] The resulting lithographic printing plate precursor (PP-c) prepared in this example was subjected to scanning exposure by using 830 nm laser with a drum rotation speed of 220 rpm and a laser power of 12 W on a Kodak 800 Quantum-II type CTP platesetter. The exposed original plate was developed with Konita DV-T developer solution at 25° C. for 35 s. After which, the coating on the exposed area of the resulting lithographic printing plate precursor was completely dissolved, while the coating on the unexposed area remained. The image was clear and the edges were sharp and neat.

Imageable Element Example 4: Preparation of the Kithographic Printing Plate Precursor (PP-d)

[0097] (1) Inner coating: 0.50 g of polymer binder PB-d and 0.01 g of victoria blue BO were dissolved in a mixed solvent of 4.5 g of ethylene glycol monomethyl ether, 3.5 g of butanone-2, 1.0 g of butyrolactone and 1.0 g of water. The above-mentioned composition solution was coated on the aluminum plate substrate which has been treated by electrochemical roughening and anodizing using a spin coating method, and then dried in an oven at 145° C. for 3 min to obtain the inner coating having a weight of 1.2 g/m.sup.2. The inner coating did not dissolve or fall off significantly after soaking in isopropanol for 1 min, showing its excellent alcohol resistance.

[0098] (1) Outer coating: 0.46 g of phenolic resin PD-140A, 0.02 g of infrared absorber IRD-85 and 0.02 g of methyl violet were dissolved in a mixed solvent of 5.8 g of propylene glycol monomethyl ether and 3.8 g of butanone-2. The composition solution was coated on the above-mentioned inner coating using a spin coating method, and then dried in an oven at 145° C. for 3 min to obtain the lithographic printing plate precursor (PP-d) having a total weight of the inner coating and outer coating of approximately 2.1 g/m.sup.2.

[0099] The resulting planographic printing plate precursor (PP-d) prepared in this example was subjected to scanning exposure by using 830 nm laser with a drum rotation speed of 220 rpm and a laser power of 12 W on a Kodak 800 Quantum-II type CTP platesetter. The exposed original plate was developed with Konita DV-T developer solution diluted with water at 25° C. for 15 s. After which, the coating on the exposed area of the resulting lithographic printing plate precursor was completely dissolved, while the coating on the unexposed area remained. The image was clear and the edges were sharp and neat.

Imageable Element Example 5: Preparation of a Lithographic Printing Plate Precursor (PP-e)

[0100] (1) Inner coating: 0.50 g of polymer binder PB-e, 0.005 g of infrared absorber IRD67 and 0.01 g of victoria blue BO were dissolved in a mixed solvent of 4.5 g of ethylene glycol monomethyl ether, 3.5 g of butanone-2, 1.0 g of butyrolactone and 1.0 g of water. The above-mentioned composition solution was coated on the aluminum plate substrate which has been treated by electrochemical roughening and anodizing using a spin coating method, and then dried in an oven at 145 ° C. for 3 min to obtain the inner coating having a weight of 1.2 g/m.sup.2. The inner coating did not dissolve or fall off significantly after soaking in isopropanol for 1 min, showing its excellent alcohol resistance.

[0101] (2) Outer coating: 0.23 g of phenolic resin PD-140A, 0.23 g of phenolic resin LB6564, 0.02 g of infrared absorber IRD-85 and 0.02 g of methyl violet were dissolved in a mixed solvent of 5.8 g of propylene glycol monomethyl ether and 3.8 g of butanone-2. The composition solution was coated on the above-mentioned inner coating using a spin coating method, and then dried in an oven at 145° C. for 3 min to obtain the lithographic printing plate precursor (PP-e) having a total weight of the inner coating and outer coating of approximately 2.1 g/m.sup.2.

[0102] The resulting planographic printing plate precursor (PP-e) prepared in this example was subjected to scanning exposure by using 830 nm laser with a drum rotation speed of 220 rpm and a laser power of 12 W on a Kodak 800 Quantum-II type CTP platesetter. The exposed original plate was developed with a mixture of Konita DV-T developer and ethylene glycol at 25° C. for 35 s. After which, the coating on the exposed area of the resulting lithographic printing plate precursor was completely dissolved, while the coating on the unexposed area remained. The image was clear and the edges were sharp and neat.

Imageable Element Example 6: Preparation of a Lithographic Printing Plate Precursor (PP-f)

[0103] (1) Inner coating: 0.50 g of polymer binder PB-f and 0.01 g of victoria blue BO were dissolved in a mixed solvent of 6.5 g of ethylene glycol monoethyl ether, 2.0 g of butanone-2, 0.5 g of butyrolactone and 0.5 g of water. The above-mentioned composition solution was coated on the aluminum plate substrate which has been treated by electrochemical roughening and anodizing using a spin coating method, and then dried in an oven at 145° C. for 3 min to obtain the inner coating having a weight of 1.2 g/m.sup.2. The inner coating did not dissolve or fall off significantly after soaking in isopropanol for 1 min, showing its excellent alcohol resistance.

[0104] (2) Outer coating: 0.46 g of phenolic resin PD-140A, 0.02 g of infrared absorber IRD-85 and 0.02 g of methyl violet were dissolved in a mixed solvent of 5.8 g of propylene glycol monomethyl ether and 3.8 g of butanone-2. The composition solution was coated on the above-mentioned inner coating using a spin coating method, and then dried in an oven at 145° C. for 3 min to obtain the lithographic printing plate precursor (PP-f) with a total weight of the inner coating and outer coating of approximately 2.1 g/m.sup.2.

[0105] The resulting lithographic printing plate precursor (PP-f) prepared in this example was subjected to scanning exposure by using 830 nm laser with a drum rotation speed of 220 rpm and a laser power of 12 W on a Kodak 800 Quantum-II type CTP platesetter. The exposed original plate was developed with a mixture of Konita DV-T developer and ethylene glycol methyl ether at 25° C. for 35 s. After which, the coating on the exposed area of the resulting lithographic printing plate precursor was completely dissolved, while the coating on the unexposed area remained. The image was clear and the edges were sharp and neat.

Imageable Element Example 7: Preparation of the Lithographic Printing Plate Precursor (PP-g)

[0106] (1) Inner coating: 0.45 g of polymer binder PB-g, 0.05 g of a copolymer of methyl methacrylate and methacrylic acid and 0.01 g of victoria blue BO were dissolved in a mixed solvent of 6.5 g of ethylene glycol monoethyl ether and 2.0 g of butanone-2, 0.5 g of butyrolactone and 0.5 g of water. The above-mentioned composition solution was coated on the aluminum plate substrate which has been treated by electrochemical roughening and anodizing using a spin coating method, and then dried in an oven at 145 ° C. for 3 min to obtain the inner coating having a weight of 1.2 g/m.sup.2. The inner coating did not dissolve or fall off significantly after soaking in isopropanol for 1 min, showing its excellent alcohol resistance.

[0107] (2) Outer coating: 0.46 g of phenolic resin EP0090G, 0.02 g of infrared absorber IRD-85, 0.01 g of acid generator WPI-170 and 0.02 g of methyl violet were dissolved in a mixed solvent 5.8 g of propylene glycol monomethyl ether and 3.8 g of butanone-2. The composition solution was coated on the above-mentioned inner coating using a spin coating method, and then dried in an oven at 145° C. for 3 min to obtain the lithographic printing plate precursor (PP-g) having a total weight of the inner coating and outer coating of approximately 2.1 g/m.sup.2.

[0108] The resulting planography printing plate precursor (PP-g) prepared in this example was subjected to scanning exposure by using 830 nm laser with a drum rotation speed of 220 rpm and a laser power of 12 W on a Kodak 800 Quantum-II type CTP platesetter. The exposed original plate was developed with Konita DV-T developer solution diluted with water at 25° C. for 35 s. After which, the coating on the exposed area of the resulting lithographic printing plate precursor was completely dissolved, while the coating on the unexposed area remained. The image was clear and the edges were sharp and neat.

Imageable Element Example 8: Preparation of a Lithographic Printing Plate Precursor (PP-h)

[0109] (1) Inner coating: 0.23 g of polymer binder PB-h, 0.23 g of polymer binder PB-f and 0.01 g of victoria blue BO were dissolved in a mixed solvent of 6.5 g of ethylene glycol monoethyl ether, 2.0 g of butanone-2, 0.5 g of butyrolactone and 0.5 g of water. The above-mentioned composition solution was coated on the aluminum plate substrate which has been treated by electrochemical roughening and anodizing using a spin coating method, and then dried in an oven at 145° C. for 3 min to obtain the inner coating having a weight of 1.2 g/m.sup.2. The inner coating did not dissolve or fall off significantly after soaking in isopropanol for 1 min, showing its excellent alcohol resistance.

[0110] (2) Outer coating: 0.46 g of phenolic resin PD-140A, 0.02 g of infrared absorber IRD-85, 0.01 g of acid generator triazine D and 0.02 g of methyl violet were dissolved in a mixed solvent of 5.8 g of propylene glycol monomethyl ether and 3.8 g of butanone-2. The composition solution was coated on the above-mentioned inner coating using a spin coating method, and then dried in an oven at 145° C. for 3 min to obtain the lithographic printing plate precursor (PP-h) having a total weight of the inner coating and outer coating of approximately 2.1 g/m.sup.2.

[0111] The resulting planography printing plate precursor (PP-h) prepared in this example was subjected to scanning exposure by using 830 nm laser with a drum rotation speed of 220 rpm and a laser power of 12 W on a Kodak 800 Quantum-II type CTP platesetter. The exposed original plate was developed with Konita DV-T developer diluted with water at 25° C. for 35 s. After which, the coating on the exposed area of the resulting lithographic printing plate precursor was completely dissolved, while the coating on the unexposed area remained. The image was clear and the edges were sharp and neat.