Method of manufacturing a thermally imageable element
View Patent ↗Methods of manufacturing multi-layer thermally imageable elements useful as lithographic printing plate precursors are disclosed. The elements comprise a substrate, an underlayer, and an imageable layer. The imageable layer comprises a first polymeric material and o-diazonaphthoquinone containing material. After the underlayer has been coated over the substrate and the imageable layer has been coated over the underlayer, the element is heated to between about 130° C. and about 200° C. for a time sufficient to decrease the sensitivity of the imageable element to the white light.
1. A method for forming a multi-layer positive-working imageable element, the imageable element comprising:
a substrate comprising a hydrophilic surface;
an underlayer over the hydrophilic surface of the substrate; and
an imageable layer over the underlayer;
the method comprising the steps of:
(a) coating the underlayer over the hydrophilic surface of the substrate;
(b) coating the imageable layer over the underlayer; and
(c) heating the imageable element at a temperature between about 130° C. and about 200° C. for a time sufficient to increase resistance of the imageable element to an alkaline developer and to decrease the white light sensitivity of the imageable element;
in which:
the imageable element comprises a photothermal conversion material;
the imageable layer is ink receptive;
the imageable layer is insoluble in the alkaline developer;
the imageable layer comprises:
a first polymeric material, and
an o-diazonaphthoquinone containing material; and
the underlayer comprises a second polymeric material.
2. The method of claim 1 in which the imageable element is heated to a temperature between about 130° C. and about 200° C. for about 30 seconds to about 10 minutes.
3. The method of claim 1 in which the second polymeric material is selected from the group consisting of (1) copolymers that comprise a carboxylic acid, an N-substituted cyclic imide, and an amide functional group; (2) copolymers that comprise a pendent urea group; and (3) copolymers that comprise a pendent sulfonamide group.
4. The method of claim 1 in which the o-diazonaphthoquinone containing material is either a compound that comprises an o-diazonaphthoquinone moiety attached to a ballasting moiety that has a molecular weight of at least 1500 but less than about 5000, or a novolac resin derivatized with an o-diazonaphthoquinone moiety.
5. The method of claim 4 in which the first polymeric material is either a novolac resin or a novolac resin derivatized with an o-diazonaphthoquinone moiety.
6. The method of claim 5 in which second polymeric material is selected from the group consisting of (1) copolymers that comprise a carboxylic acid, an N-substituted cyclic imide, and an amide functional group; (2) copolymers that comprise a pendent urea group; and (3) copolymers that comprise a pendent sulfonamide group.
7. The method of claim 6 in which the imageable element is heated to a temperature between about 130° C. and about 200° C. for about 30 seconds to about 10 minutes.
8. The method of claim 1 in which the first polymeric material is either a novolac resin or a novolac resin derivatized with an o-diazonaphthoquinone moiety.
9. The method of claim 8 in which the second polymeric material is a copolymer that comprises about 25 to about 75 mol % of N-phenylmaleimide; about 10 to about 50 mol % of methacrylamide; and about 5 to about 30 mol % of methacrylic acid.
10. The method of claim 9 in which the second polymeric material comprises about 35 to about 60 mol % of the N-phenylmaleimide; about 15 to about 40 mol % of the methacrylamide; and about 10 to about 30 mol % of the methacrylic acid.
11. The method of claim 8 in which the second polymeric material comprises about 20 to 80 wt % of one of more monomers represented by the general formula:
CH 2 ═C(R)—CO 2 —X—NH—CO—NH—Y—Z,
in which R is —H or —CH3; X is a bivalent linking group; Y is a substituted or unsubstituted bivalent aromatic group; and Z is —OH, —COOH, or —SO 2 NH 2 .
12. The method of claim 11 in which R is CH 3; X is —(CH 2 CH 2 )—; Y is unsubstituted 1,4-phenylene; and Z is —OH.
13. The method of claim 8 in which the second polymeric material comprises (1) about 10 to 90 mol % of a sulfonamide containing monomer unit; (2) acrylonitrile or methacrylonitrile; and (3) methyl methacrylate or methyl acrylate.
14. The method of claim 8 in which the imageable element is heated to a temperature between about 130° C. and about 200° C. for about 30 seconds to about 10 minutes.
15. The method of claim 1 in which the first polymeric material is a novolac resin and the o-diazonaphthoquinone containing material is novolac resin derivatized with an o-diazonaphthoquinone moiety.
16. The method of claim 1 in which the second polymeric material is a copolymer that comprises about 25 to about 75 mol % of N-phenylmaleimide; about 10 to about 50 mol % of methacrylamide; and about 5 to about 30 mol % of methacrylic acid.
17. The method of claim 1 in which the first polymeric material is novolac resin and the o-diazonaphthoquinone containing material is a compound that comprises an o-diazonaphthoquinone moiety attached to a ballasting moiety that has a molecular weight of at least 1500 but less than about 5000.
18. The method of claim 1 in which the second polymeric material is a copolymer that comprises about 25 to about 75 mol % of N-phenylmaleimide; about 10 to about 50 mol % of methacrylamide; and about 5 to about 30 mol % of methacrylic acid.
19. A multi-layer positive-working imageable element, the element comprising a substrate comprising a hydrophilic surface; an underlayer over the hydrophilic surface of the substrate; and an imageable layer over the underlayer;
the element prepared by a method comprising the steps of:
(a) coating the underlayer over the hydrophilic surface of the substrate;
(b) coating the imageable layer over the underlayer; and
(c) heating the imageable element at a temperature between about 130° C. and about 200° C. for a time sufficient to increase resistance of the imageable element to an alkaline developer and to decrease the white light sensitivity of the imageable element;
in which:
the imageable element comprises a photothermal conversion material;
the imageable layer is ink receptive;
the imageable layer is insoluble in the alkaline developer;
the imageable layer comprises:
a first polymeric material, and
an o-diazonaphthoqulnone containing material; and
the underlayer comprises a second polymeric material.
20. The element of claim 19 in which the imageable element is heated to a temperature between about 130° C. and about 200° C. for about 30 seconds to about 10 minutes.