| (19) |
 |
|
(11) |
EP 1 506 856 A3 |
| (12) |
EUROPEAN PATENT APPLICATION |
| (88) |
Date of publication A3: |
|
30.03.2005 Bulletin 2005/13 |
| (43) |
Date of publication A2: |
|
16.02.2005 Bulletin 2005/07 |
| (22) |
Date of filing: 08.06.1999 |
|
|
| (84) |
Designated Contracting States: |
|
BE DE ES FR GB IT NL SE |
| (30) |
Priority: |
23.06.1998 US 90300 P
29.04.1999 US 301866
|
| (62) |
Application number of the earlier application in accordance with Art. 76 EPC: |
|
99928429.2 / 1011970 |
| (71) |
Applicant: Kodak Polychrome Graphics LLC |
|
Norwalk, Connecticut 06851 (US) |
|
| (72) |
Inventors: |
|
- Shimazu, Ken-Ichi
New York, NY 10704 (US)
- Patel, Jayanti
New Jersey, NJ 07675 (US)
- Saraiya, Shashikant
New Jersey, NJ 08857 (US)
- Merchant, Nishith
New Jersey, NJ 07047 (US)
- Savariar-Hauck, Celin
37534 Badenhaussen (DE)
- Timpe, Hans-Joachim
37520 Osterode (DE)
- McCullough, Christopher
Fort Collins Colorado 80526 (US)
|
| (74) |
Representative: Pidgeon, Robert John et al |
|
Appleyard Lees 15 Clare Road
Halifax West Yorkshire HX1 2HY
Halifax West Yorkshire HX1 2HY (GB) |
|
| |
|
| (54) |
Positive-working thermal imaging element and positive-working lithographic printing
plate precursor |
(57) A positive-working thermal imaging element, which can be imaged by thermal energy
is made up of a hydrophilic substrate, and a composite layer structure composed of
two layer coatings. The substrate has a roughened surface of average roughness Ra
in the range from 0.1 to 0.8 µm, preferably 0.1 to 0.4 µm. The first layer of the
composite is composed of an aqueous developable polymer mixture containing a photothermal
conversion material which is contiguous to the hydrophilic substrate. The second layer
of the composite is composed of one or more non-aqueous soluble polymers which are
soluble or dispersible in a solvent which does not dissolve the first layer. The second
layer may also contain a photothermal conversion material. The positive-working thermal
imaging element is exposed with an infrared laser or a thermal print head. Upon aqueous
development of the imaged positive-working thermal imaging element unexposed portions
are ink-receptive.