| 摘要 |
A plate cleaning agent is provided capable of suitably treating a plate surface without causing blinding in a lithographic printing plate obtained by platemaking from a photopolymerizable lithographic printing plate precursor provided with an oxygen-blocking protective layer, and particularly an oxygen-blocking protective layer containing inorganic fine particles. The invention provides: an emulsified plate cleaning agent for a lithographic printing plate, which is used on a lithographic printing plate obtained by platemaking from a photopolymerizable lithographic printing plate precursor provided with an oxygen-blocking protective layer, wherein the total cation content of a contained salt based on the total weight of the plate cleaning agent is 0.5% by weight or more, and 30% by weight or more of the cations are at least one type selected from the group consisting of potassium, cesium and rubidium based on the weight of all cations; and a plate surface treatment method for a lithographic printing plate, this method comprising: cleaning a lithographic printing plate, obtained by platemasking from a photopolymerizable lithographic printing plate precursor provided with an oxygen-blocking protective layer, with the above-mentioned emulsified plate cleaning agent for a lithographic printing plate. |
