Patent ID: 7132212

Claim:
A presensitized plate comprising: a support for a lithographic printing plate including an anodized layer formed on an aluminum plate and a recording layer recordable by infrared laser exposure on the support, wherein in a section of the anodized layer after the recording layer is provided, an atomicity ratio of carbon to aluminum (C/Al) represented by a following formula (1) is 1.0 or less: C/Al=(I c /S c )/(I al /S al ) (1) I c : carbon (KLL) Auger electron differential peak-to-peak amplitude I al : aluminum (KLL) Auger electron differential peak-to-peak amplitude S c : relative sensitivity factor of carbon (KLL) Auger electron S al : relative sensitivity factor of aluminum (KLL) Auger electron wherein the recording layer is formed on the anodized layer directly or through an undercoat layer, and the recording layer is a thermosensitive layer containing a fine particle polymer having a thermo-reactive functional group, or microcapsules containing a compound having a thermo-reactive functional group, a thermosensitive layer using a negative working infrared laser recording material, a thermosensitive layer using a positive infrared laser recording material comprising alkali soluble polymer, a compound dissolved with the alkali soluble polymer to reduce alkaline solubility, and a compound for absorbing infrared radiation, or a thermosensitive layer using a sulfonate type infrared laser recording material.