Method for thermally processing photosensitive printing sleeves
View Patent ↗An improved method of manufacturing a photosensitive printing element that minimizes relief variation and improves image fidelity. The method involves a step of pre-curing the first (floor layer) of photocurable material prior to depositing an additional layer or layers of photocurable material that may be imaged and developed to produce a desired relief image on the surface of the photosensitive printing element. The photosensitive printing element is then thermally developed by contacting the photosensitive printing element with at least one roll that is capable of moving over at least a portion of the imaged surface of the flexographic printing element to remove the softened or melted non-crosslinked photopolymer. Non-crosslinked photopolymer on the imaged and exposed surface of the flexographic printing element can be softened or melted by positioning a heater adjacent to the imaged surface of the flexographic printing element and/or heating the at least one roll that contactable with the imaged surface of the flexographic printing element.
1. A cylindrical thermally developable photosensitive printing element comprising:
a) a support layer;
b) optionally, a compressible layer deposited on the support layer;
c) a first layer of photocurable material deposited on the support layer or the optional compressible layer; said first layer of photocurable material being pre-cured;
d) at least a second layer of photocurable material deposited on the cured first layer of photocurable material; and
e) a masking layer deposited on the at least second layer of photocurable material that allows for the selective polymerization of the at least second layer of photocurable material; wherein the first layer of photocurable material is fully cured before the second layer is deposited.
2. The photosensitive printing element according to claim 1 , wherein the first layer of photocurable material is ground, sanded, or machined to achieve a desired thickness.
3. A printing element according to claim 1 wherein the support layer comprises a polymer resin reinforced with fibrous materials.
4. A printing element according to claim 1 wherein the compressible layer comprises hollow microspheres.
5. A printing element according to claim 1 wherein the support layer is substantially uniformly translucent.
6. A method of manufacturing a photosensitive printing element comprising the steps of:
a) providing a photosensitive printing element, the photosensitive printing element comprising:
(i) a support layer;
(ii) a first layer of photocurable material which has been pre-cured;
(iii) at least a second layer of photocurable material on the first layer photocurable material; and
(iv) a masking layer on the second layer of photocurable material;
b) ablating portions of the masking layer to create a pattern;
c) exposing the printing element to actinic radiation such that portions of the second photocurable layer are cured;
d) exposing the printing element to heat such that any uncured photocurable material is melted or softened;
e) causing contact between the printing element and a blotting material such that the blotting material removes the melted or softened uncured photocurable material.
7. A method according to claim 6 wherein the blotting material is contacted with the printing element by means of at least one roll.
8. A method according to claim 7 wherein the at least one roll traverses the length of the printing element.
9. A method according to claim 8 wherein the at least one roll traverses the length of the printing element in a spiral or stepwise manner.