| Method of manufacturing lithographic printing plate support -> Monitor Keywords |
|
|
  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 20060032759. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] 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 used for a presensitized plate which has both an excellent scumming resistance and a good press life. [0002] Lithography is a printing process which makes use of a nature that water and oil are essentially unmixable with each other. On the printing surface of a lithographic printing plate used in this process, areas that receive water and repel an oil-based ink (hereinafter referred to as "non-image areas") and areas that repel water and receive an oil-based ink (hereinafter referred to as "image areas") are provided. [0003] The surface of an aluminum support for lithographic printing plates used for a lithographic printing plate (hereinafter also referred to simply as "a lithographic printing plate support") is required to have various conflicting characteristics. For instance, it should be excellent in water wettability and water receptivity because of being so used as to carry non-image areas and at the same time should give good adhesion to the image recording layer formed on it. If the surface of a lithographic printing plate support exhibits too low a water wettability, non-image areas are to be stained with ink upon printing, resulting in generation of dirt on a blanket cylinder or even so-called scumming, that is to say, the scumming resistance is reduced. In addition, if the water receptivity of the surface is too low, certain inconveniences will arise at the time of printing, including plugging of shadows, unless fountain solution is increased in amount. On the other hand, if the adhesion between the support surface and the image recording layer is too poor, the image recording layer is liable to peel off and accordingly the durability (press life) is decreased during printing of a large number of printed sheets. [0004] In fact, the surface of a lithographic printing plate support is subjected to graining treatment and other surface treatments in order to improve various characteristics such as scumming resistance and press life. Examples of a known graining treatment include a mechanical graining treatment such as ball graining, brush graining, wire graining, and blast graining; an electrochemical graining treatment in which alternating current is passed through an aluminum plate immersed in an acidic solution; chemical etching (chemical graining treatment); and a combination thereof. [0005] Among such graining treatments, the electrochemical graining treatment as above provides recesses (pits) with an average diameter of 1 to 5 .mu.m uniformly through the entire surface of an aluminum plate, with an aqueous solution containing nitric acid being used as the acidic solution. If an aqueous solution containing hydrochloric acid is used as the acidic solution, pits with an average diameter of 0.01 to 0.5 .mu.m are formed uniformly through the entire surface of an aluminum plate. [0006] In the case where an aluminum plate is initially subjected to an electrochemical graining treatment using an aqueous solution containing nitric acid as the acidic solution and then to an electrochemical graining treatment using an aqueous solution containing hydrochloric acid as the acidic solution, the aluminum plate will have asperities formed through its entire surface, in which pits with an average diameter of 0.01 to 0.5 .mu.m are superimposed on pits with an average diameter of to 5 .mu.m. A lithographic printing plate in which an aluminum plate of such a surface profile as above is used as the lithographic printing plate support is excellent in both scumming resistance and press life. [0007] In addition, JP 48-28123 B (the term "JP ______ 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 in 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.. SUMMARY OF THE INVENTION [0008] In the former case, however, it is necessary to perform two kinds of electrochemical graining treatments, an electrochemical graining treatment using an aqueous solution containing nitric acid as the acidic solution, and then an electrochemical graining treatment using an aqueous solution containing hydrochloric acid as the acidic solution, In other words, manufacturing of a lithographic printing plate support needs an increased number of processes and is more complicated. [0009] As for the latter case, namely the method described in JP 48-28123 B, the present inventors reviewed it to find that the disclosed techniques provide pits with an average diameter of about 1 to 5 .mu.m and coarse recesses with an average diameter exceeding 10 .mu.m on the aluminum plate surface in a mixed manner and that a lithographic printing plate in which an aluminum plate of such a surface profile is used as the lithographic printing plate support has neither an adequate scumming resistance nor press life. [0010] It is an object of the present invention to provide a method of manufacturing a lithographic printing plate support which makes it possible to obtain a presensitized plate having both an excellent scumming resistance and a good press life by a single electrochemical graining treatment. [0011] In order to achieve the above and other objects, the present inventors have intensively studied to finally find out that, if an aluminum plate is subjected to an electrochemical graining treatment, in which alternating current is passed through the aluminum plate in an aqueous solution containing at least chloride ion and nitrate ion so that the total amount of electricity when the aluminum plate serves as an anode is 100 to 300 C/dm.sup.2, so as to obtain a lithographic printing plate support, a presensitized plate in which the lithographic printing plate support is used has both an excellent scumming resistance and a good press life, even though the aluminum plate is subjected to one electrochemical graining treatment only. [0012] According to the preset invention, there are provided the following (1) to (6). [0013] (1) A method of manufacturing a lithographic printing plate support comprising a step of subjecting an aluminum plate to an electrochemical graining treatment in which alternating current is passed through the aluminum plate in an aqueous solution containing at least chloride ion and nitrate ion so that total amount of electricity when the aluminum plate serves as an anode is 100 to 300 C/dm.sup.2. [0014] (2) The method of manufacturing a lithographic printing plate support according to (1) as above, wherein the aqueous solution contains hydrochloric acid and nitric acid. [0015] (3) The method of manufacturing a lithographic printing plate support according to (1) or (2) as above, wherein the aqueous solution has a chloride ion concentration of 3 g/L or more and a nitrate ion concentration of 0.50 g/L or more. [0016] (4) The method of manufacturing a lithographic printing plate support according to any one of (1) to (3) as above, wherein the aqueous solution has a pH of 0.8 or less. [0017] (5) The method of manufacturing a lithographic printing plate support according to any one of (1) to (4) as above, wherein the aqueous solution contains 2 g/L or more of aluminum ions. [0018] (6) The method of manufacturing a lithographic printing plate support according to any one of (1) to (5) as above, wherein the aluminum plate has a pattern of recessed and protruded portions provided on its surface. [0019] As will be described below, according to the present invention, the lithographic printing plate support can be obtained that is used for a presensitized plate which has both an excellent scumming resistance and a good press life when made into a lithographic printing plate. Moreover, the lithographic printing plate support used for a presensitized plate which has both an excellent scumming resistance and a good press life when made into a lithographic printing plate can be obtained by subjecting an aluminum plate to a single electrochemical graining treatment. BRIEF DESCRIPTION OF THE DRAWINGS [0020] In the accompanying drawings: [0021] FIG. 1 is a schematic cross-sectional view of an apparatus for rinsing with a free-falling curtain of water that is used for rinsing in the method of manufacturing a lithographic printing plate support according to the present invention; 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. Start now! - Receive info on patent apps like Method of manufacturing lithographic printing plate support or other areas of interest. ### Previous Patent Application: Method and system for idle state operation Next Patent Application: Method of manufacturing lithographic printing plate support Industry Class: Electrolysis: processes, compositions used therein, and methods of preparing the compositions ### FreshPatents.com Support Thank you for viewing the Method of manufacturing lithographic printing plate support patent info. IP-related news and info Results in 0.16669 seconds Other interesting Feshpatents.com categories: Daimler Chrysler , DirecTV , Exxonmobil Chemical Company , Goodyear , Intel , Kyocera Wireless , |
||
