Method of creating a digital mask for flexographic printing elements in situ
View Patent ↗A method of creating a digital mask in situ for use in a process of making digital flexographic printing elements. The digital mask is created by laminating the negative image that is the by-product of a thermal proofer to a photosensitive printing plate. Thereafter, the photosensitive printing element can be imaged, exposed, and developed in the usual manner.
1. A method of creating a digital mask for imaging a photosensitive printing element, comprising the steps of:
a) providing a donor element and a receptor element in a thermal proofer, wherein the donor element is capable of transferring material to the receptor element to create an image on the receptor element while retaining a negative of the image on the donor element;
b) outputting a desired image to the thermal proofer;
c) transferring material from the donor element to the receptor element to create the image;
d) separating the donor element from the receptor element and retaining the donor element; and
e) laminating the donor element containing the negative image therein to a top surface of the photosensitive printing element.
2. The method according to claim 1 , further comprising the steps of exposing and developing the photosensitive printing element to reveal the relief image.
3. The method according to claim 2 , wherein the donor sheet comprises a thermally transferable layer disposed on a backing layer.
4. The method according to claim 3 , wherein the thermally transferable layer comprises a dye or pigment.
5. The method according to claim 4 , wherein the thermally transferable layer further comprises at least one binder.
6. The method according to claim 3 , comprising the step of removing the backing layer from the donor element prior to exposing and developing the printing element.
7. The method according to claim 2 , wherein the exposing step comprising exposing the photosensitive printing element through the negative image of the donor sheet to actinic radiation to selectively cross-link and cure portions of the photosensitive printing element not covered by the donor element.
8. The method according to claim 2 , wherein the developing step comprises thermally developing the photosensitive printing element to remove the donor element and the uncured portions of the photosensitive printing element.