| Method of manufacturing lithographic printing plate support -> Monitor Keywords |
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  Method of manufacturing lithographic printing plate supportRelated Patent Categories: Electrolysis: Processes, Compositions Used Therein, And Methods Of Preparing The Compositions, Electrolytic Coating (process, Composition And Method Of Preparing Composition), Forming Nonmetal Coating, Predominantly Aluminum Substrate, AnodizingThe Patent Description & Claims data below is from USPTO Patent Application 20060032760. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] The entire contents of literatures cited in this specification are incorporated by reference. BACKGROUND OF THE INVENTION [0002] The present invention relates to a method of manufacturing a lithographic printing plate support. More specifically, the invention relates to a method of manufacturing a lithographic printing plate support that is used for a presensitized plate having excellent scumming resistance and a long press life. [0003] An aluminum support for a lithographic printing plate that is used for a lithographic printing plate (hereinafter simply referred to as a "lithographic printing plate support") is manufactured by subjecting an aluminum plate to graining treatment and other surface treatments. Well known methods for the graining treatment include, for example, mechanical graining treatment, electrochemical graining treatment, chemical graining treatment (chemical etching) and a combination thereof. [0004] Among these, the method in which an alternating current is passed through an aluminum plate in an aqueous solution containing hydrochloric acid is widely used in the electrochemical graining treatment, because fine asperities can be formed on the surface of the aluminum plate. [0005] For example, JP 48-28123 B (the term "JP XX-XXXXXX B" as used herein means an "examined Japanese patent publication") describes a method of manufacturing an offset printing plate which includes a step of graining an aluminum plate or an aluminum alloy plate by alternating current electrolysis An a solution containing 1 to 3% of hydrochloric acid and nitric acid at a current density exceeding 10 A/dm.sup.2, a step of slightly etching in an aqueous alkali solution, and a step of performing anodizing treatment to form an anodized layer having a thickness of not more than 5.mu.. [0006] JP 51-6571 B describes a method of electrolyzing an aluminum sheet for a printing plate in which the aluminum sheet is continuously electrolyzed using an alternating current in an electrolyte solution containing 1 to 4 wt % of hydrochloric acid and 0.1 to 1 wt % of sulfuric acid. [0007] JP 53-129132 A (the term "JP XX-XXXXXX A" as used herein means an "unexamined published Japanese patent application") describes a method of electrolytically graining an aluminum sheet in which the aluminum sheet is immersed in an aqueous electrolyte solution containing 1 wt %.of hydrochloric acid and 4 to 6 wt % of nitric acid as the electrolyte, and an alternating current of 150 to 300 A/929 cm.sup.2 (1 square foot) is applied to the aqueous electrolyte solution while maintaining the solution at a temperature of not less than 40.degree. C. [0008] JP 55-31199 B describes a method of graining an aluminum plate for use as a printing plate in which the aluminum plate whose surface was cleaned according a conventional procedure is subjected to an alternating current electrolysis at a current density of 40 to 150 A/dm.sup.2 in an electrolytic bath containing 0.5 to 2.5% of nitric acid and not more than 0.2% of hydrochloric acid. [0009] JP 55-17579 A describes a method of manufacturing a printing plate support in which an aluminum plate is etched by alternating current electrolysis in an aqueous electrolyte solution containing (a) hydrogen chloride or nitric acid and (b) phosphoric acid or a salt thereof. [0010] JP 56-101896 A describes a method of manufacturing a lithographic printing plate support in which the surface of an aluminum or aluminum alloy plate is subjected to an electrolytic etching in an electrolyte solution containing hydrochloric acid, nitric acid or a mixture acid thereof, then the aluminum or aluminum alloy plate is anodized in an electrolyte solution containing nitric acid, and the surface of the anodized plate is further subjected to mechanical polishing. SUMMARY OF THE INVENTION [0011] However, a lithographic printing plate manufactured using a lithographic printing plate support obtained by performing graining treatment according to the above-mentioned conventional method which uses the alternating current electrolysis in an aqueous solution containing hydrochloric acid had difficulty in fully satisfying both the properties of press life and scumming resistance. [0012] Therefore, an object of the present invention is to provide a method of manufacturing a lithographic printing plate support that is capable of obtaining a presensitized plate having excellent scumming resistance and a long press life using the alternating current electrolysis in an aqueous solution containing hydrochloric acid. [0013] The inventors of the present invention has made intensive studies to achieve the above object and as a result found that when an aluminum plate is subjected at least to a first electrochemical graining treatment in which an alternating current is passed through the aluminum plate in an aqueous solution containing hydrochloric acid and nitric acid and a second electrochemical graining treatment in which an alternating current is passed through the aluminum plate in an aqueous solution containing hydrochloric acid in this order to obtain a lithographic printing plate support, a presensitized plate using the support has both a long press life and excellent scumming resistance. The present invention has been completed based on the finding. [0014] Accordingly, the present invention provides the following aspects (1) to (5): [0015] (1) A method of manufacturing a lithographic printing plate support comprising the step of: [0016] subjecting an aluminum plate at least to a first electrochemical graining treatment in which a first alternating current is passed through the aluminum plate in a first aqueous solution containing hydrochloric acid and nitric acid and a second electrochemical graining treatment in which a second alternating current is passed through the aluminum plate in a second aqueous solution containing hydrochloric acid in this order to obtain the lithographic printing plate support. [0017] (2) The method according to (1), wherein the aluminum plate has a pattern of recessed and protruded portions on a surface thereof. [0018] (3) The method according to (1) or (2), wherein the first alternating current is passed through the aluminum plate in the first electrochemical graining treatment so that a total amount of electricity when the aluminum plate serves as an anode is 100 to 300 C/dm.sup.2. [0019] (4) The method according to any one of (1) to (3), wherein the second alternating current is passed through the aluminum plate in the second electrochemical graining treatment so that a total amount of electricity when the aluminum plate serves as an anode is 100 to 300 C/dm.sup.2. [0020] (5) The method according to any one of (1) to (4), wherein the first aqueous solution used in the first electrochemical graining treatment has a hydrochloric acid concentration of 3 to 30 g/L and a nitric acid concentration of 0.5 to 15 g/L. [0021] As will be described later, the present invention can provide a lithographic printing plate support used for a presensitized plate which has excellent scumming resistance and a long press life when processed into a lithographic printing plate. BRIEF DESCRIPTION OF THE DRAWINGS Continue reading... Full patent description for Method of manufacturing lithographic printing plate support Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Method of manufacturing lithographic printing plate support patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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