Means for attaching a printing plate to a printing cylinder
View Patent ↗A means for removably attaching a printing plate to a printing cylinder using an intermediate sheet of photopolymer. The tack of the photopolymer is used to attach itself to the printing cylinder and to attach the printing plate to it. Microspheres are incorporated into the photopolymer sheet to provide a cushioning effect when in use on the printing press.
1. A method for removably attaching a printing plate to a printing cylinder, said method comprising:
(i) attaching a photopolymer sheet to the printing cylinder which photopolymer sheet comprises first and second major faces which are opposed to each other wherein the first major face contacts and attaches to the printing cylinder and wherein the first and second major faces have a surface tack of at least 5.88 Newtons as measured by ASTM standard D-2979-95;
(ii) contacting and attaching the printing plate to the second major face;
wherein the photopolymer sheet comprises:
(a) a binder;
(b) at least one monomer;
(c) a photoinitiator; and
(d) microspheres with a diameter of less than 90 microns, and
wherein said photopolymer sheet is partially cured by :exposing the sheet to ultraviolet radiation to control the surface tack of the photopolymer sheet to a level of at least 5.88 Newtons as measured by ASTM standard D-2979.
2. A method according to claim 1 wherein the resilience of the photopolymer sheet is from 8 to 20 and the softness of the photopolymer sheet is from 35 to 50.
3. A method according to claim 1 wherein the surface tack is from 6.86 to 14.7 Newtons.
4. A method according to claim 1 , wherein the photopolymer sheet at least substantially covers the printing cylinder.
5. A method according to claim 1 , comprising the step of re-establishing the surface tack of the photopolymer sheet by cleaning the photopolymer sheet with a solvent.
6. A method according to claim 5 , wherein the solvent is ethyl acetate.
7. A method according to claim 1 , wherein the microspheres comprise expanded microspheres consisting of a thermoplastic shell encapsulating a hydrocarbon.