Substrate improvements for thermally imageable composition and methods of preparation

A radiation-imageable element for lithographic printing comprising:

• a hydrophilic anodized aluminum base having a surface comprising pores having an average pore diameter from about 10 to about 100 nm;
• and coated thereon
• an image-forming layer comprising polymer particles having an average particle diameter from about 1 to about 250 nm;
• the ratio of said average pore diameter to said average particle diameter being from about 0.5:1 to about 5:1.

A method of producing an imaged element comprising the steps of:

• providing a radiation-imageable element for lithographic printing comprising:
• a hydrophilic anodized aluminum base having a surface comprising pores;
• and coated thereon, a image-forming layer comprising polymer particles, the ratio of said average pore diameter to said average particle diameter being from about 0.4:1 to about 10:1;
• and
• imagewise exposing said radiation-imageable element to radiation to produce exposed and unexposed regions.

A method of producing an imaged element having complementary ink receiving and ink rejecting regions, said method comprising the steps of:

• providing a radiation-imageable element for lithographic printing comprising:
• a hydrophilic anodized aluminum base having a surface comprising pores;
• and coated thereon, a image-forming layer comprising polymer particles, the ratio of said average pore diameter to said average particle diameter being from about 0.4:1 to about 10:1;
• imagewise exposing said radiation-imageable element to radiation to produce exposed and unexposed regions;
• and
• contacting said imagewise exposed radiation-imageable element and a developer to selectively remove said exposed or said unexposed regions.