| (19) |
 |
|
(11) |
EP 0 256 773 A3 |
| (12) |
EUROPEAN PATENT APPLICATION |
| (88) |
Date of publication A3: |
|
12.04.1989 Bulletin 1989/15 |
| (43) |
Date of publication A2: |
|
24.02.1988 Bulletin 1988/08 |
| (22) |
Date of filing: 05.08.1987 |
|
| (51) |
International Patent Classification (IPC)4: B41M 5/26 |
|
| (84) |
Designated Contracting States: |
|
BE CH DE FR GB IT LI |
| (30) |
Priority: |
14.08.1986 US 896765
|
| (71) |
Applicant: MINNESOTA MINING AND MANUFACTURING COMPANY |
|
St. Paul,
Minnesota 55133-3427 (US) |
|
| (72) |
Inventors: |
|
- Whitcomb, David R.
c/o Minnesota Mining and
P.O. Box 33427
St. Paul
Minnesota 55133 (US)
- Bjork, Jon A.
c/o Minnesota Mining and
P.O. Box 33427
St. Paul
Minnesota 55133 (US)
|
| (74) |
Representative: Baillie, Iain Cameron et al |
|
c/o Ladas & Parry
Altheimer Eck 2
80331 München
80331 München (DE) |
|
| |
|
| (54) |
Thermal imaging materials |
(57) Thermographic materials are colorless when unexposed, but provide an intense dark
image when thermally addressed. The materials comprise white ferric organophosphate,
ferric organophosphinate, or ferric organophosphonate in a clear binder with a colorless
catechol or polycatechol held in said binder in solid solution. The choice of substituents
on the catechol nucleus can give a change in the color of the thermal image together
and provide good near infrared absorption. Use of mixed catechols can give achromatic
black images. These combinations of materials show high stability at ambient temperatures.