Method for making a lithographic printing plate
A method for making a negative-working lithographic printing plate includes subjecting an image-wise exposed, developed, and dried plate precursor to UV LED radiation.
1. A method for making a negative-working lithographic printing plate, the method comprising in sequential order:
image-wise exposing a lithographic printing plate precursor including a hydrophilic support and a coating provided on the hydrophilic support, the coating including a crosslinkable composition and/or a photopolymerizable composition;
developing the lithographic printing plate precursor;
drying and/or heating the lithographic printing plate precursor to obtain a lithographic printing plate; and
subjecting the lithographic printing plate to UV LED radiation,
wherein the lithographic printing plate is subjected to the UV LED radiation for a time period between 0.1 s and 5 minutes.
2. The method according to claim 1 , wherein the coating includes a radical polymerization initiator, a radically polymerizable compound, and a binder polymer.
3. The method according to claim 1 , wherein the coating includes a diazonium compound.
4. The method according to claim 1 , wherein the subjecting the lithographic printing plate to UV LED radiation is performed with at least one UV LED having a power 10 −6 to 15 Watt.
5. The method according to claim 1 , wherein the UV LED radiation includes light having a wavelength from 315 nm to 450 nm.
6. The method according to claim 1 , wherein the image-wise exposing the lithographic printing plate precursor is performed with light having a wavelength range between 200 nm and 450 nm.
7. The method according to claim 1 , wherein the lithographic printing plate is not subjected to a preheat step between the image-wise exposing and the developing.
8. The method according to claim 1 , wherein the developing of the lithographic printing plate precursor is performed with a gum solution.
9. The method according to claim 8 , wherein the lithographic printing plate precursor is developed in a gumming station including a first gumming unit and a second gumming unit; and
the developing of the lithographic printing plate precursor includes consecutively developing the lithographic printing plate precursor in the first gumming unit and the second gumming unit with a gum solution to remove non-exposed areas of the coating from the hydrophilic support and gumming the lithographic printing plate in a single step.
10. The method according to claim 9 , wherein the first gumming unit and the second gumming unit together define a cascade system such that the gum solution used in the second gumming unit overflows into the first gumming unit.
11. The method according to claim 2 , wherein the developing of the lithographic printing plate precursor is performed with a gum solution.
12. The method according to claim 11 , wherein the lithographic printing plate precursor is developed in a gumming station including a first gumming unit and a second gumming unit; and
the developing of the lithographic printing plate precursor includes consecutively developing the lithographic printing plate precursor in the first gumming unit and the second gumming unit with a gum solution to remove non-exposed areas of the coating from the hydrophilic support and gumming the lithographic printing plate in a single step.
13. The method according to claim 12 , wherein the first gumming unit and the second gumming unit together define a cascade system such that the gum solution used in the second gumming unit overflows into the first gumming unit.
14. The method according to claim 3 , wherein the developing of the lithographic printing plate precursor is performed with a gum solution.
15. The method according to claim 14 , wherein the lithographic printing plate precursor is developed in a gumming station including a first gumming unit and a second gumming unit; and
the developing of the lithographic printing plate precursor includes consecutively developing the lithographic printing plate precursor in the first gumming unit and the second gumming unit with a gum solution to remove non-exposed areas of the coating from the hydrophilic support and gumming the lithographic printing plate in a single step.
16. The method according to claim 15 , wherein the first gumming unit and the second gumming unit together define a cascade system such that the gum solution used in the second gumming unit overflows into the first gumming unit.
17. The method according to claim 1 , wherein the developing of the lithographic printing plate precursor includes:
mounting the lithographic printing plate precursor on a plate cylinder of a lithographic printing press and rotating the plate cylinder while feeding dampening liquid and/or ink to the lithographic printing plate precursor.
18. An apparatus for processing a lithographic printing plate, the apparatus comprising:
a development/gumming section; and
a drying section; wherein
the drying section includes a drying means and at least one UV LED radiation bar, and the development/gumming section includes a first gumming unit and a second gumming unit mutually connected by a cascade to allow overflow of liquid from the second gumming unit into the first gumming unit.