Claims
- 1. In a thermographic recording process in which a dye is produced by bringing image-wise into reactive contact with the aid of heat an organic acid-reacting compound with a dye precursor compound, the improvement of producing a light stable yellow image by bringing said compound into contact with a dye precursor corresponding to the following general formula:
- X - Ar - CH = N - R.sub.1
- wherein:
- Ar represents a phenylene nucleus,
- R.sub.1 represents a phenyl group and
- X represents a ##STR37## group wherein each of R.sub.2 and R.sub.3 (same or different) represents an alkyl group, a cyanoalkyl group, a chloroalkyl group, and an alkoxy carbonylalkyl group.
- 2. A thermographic recording process according to claim 1, wherein the dye precursor compound and acid-reacting compound are applied on separate support sheets and one of them is transferred by heat from its support into reactive contact with the compound on the other support sheet.
- 3. A thermographic recording process according to claim 2, wherein the dye precursor compound and acid-reacting compound are applied on separate support sheets and the acid-reacting compound being volatile or meltable at the temperature reached in the image-wise heating is transferred from a transfer sheet to a receptor sheet which contains the dye precursor compound to form therewith a dye.
- 4. A thermographic recording process according to claim 3, wherein the dye precursor compound is applied in a coating containing a non-acidic vinyl chloride polymer or copolymer.
- 5. A thermographic recording process according to claim 3, wherein the dye precursor compound is contained in a binder coating in a ratio of 1 part by weight with respect to 1 or 20 parts by weight of binder.
- 6. A thermographic recording process according to claim 1, wherein the dye precursor compound and acid-reacting compound are used in an integral copy-sheet containing on a same support the acid-reacting compound out of direct chemical contact from the dye precursor compound but in such condition that reactive contact can be effected through heating at a temperature above 60.degree. C.
- 7. A thermographic recording process according to claim 6, wherein at least one of the reactants being the acid-reacting compound and dye precursor compound are kept out of direct chemical contact by enveloping at least one of the reactants in capsules or droplets from which the reactant is set free by image-wise heating the copy-sheet.
- 8. A thermographic recording process according to claim 7, wherein the capsules or droplets are dispersed in the paper mass of a paper sheet or in a binder or binder system containing the second reactant in dispersed or dissolved form.
- 9. A thermographic recording process according to claim 6, wherein the dye precursor compound and acid reactant are in separate binder layers and preventing chemical reactive contact at least below 60.degree. C.
- 10. A thermographic recording process according to claim 9, wherein the top layer of the binder layers has been applied from a solution in a volatile liquid, which is a non-solvent for the binder of the subjacent other layer.
- 11. A thermographic recording process according to claim 10, wherein the dye precursor compound has been incorporated in a first layer on the support of the copy-sheet in a vinyl chloride homopolymer or copolymer binder and the acid-reacting compound has been applied on top of said first layer from a solution of a polymer in ethanol or methanol.
- 12. A thermographic recording process according to claim 11, wherein the integral copy sheet is a clear transparent heat-sensitive sheet material useful in the preparation of a colour projection transparency by thermographic copying procedures and includes a first layer containing the dye precursor compound in a vinyl chloride polymer binder and a second coating bonded to said first layer containing the compound reacting as an acid in a binder mainly containing cellulose nitrate.
Priority Claims (1)
Number |
Date |
Country |
Kind |
43337/73 |
Sep 1973 |
UK |
|
Parent Case Info
This is a continuation of Ser. No. 428,805, filed Dec. 27, 1973 and now abandoned.
US Referenced Citations (9)
Foreign Referenced Citations (2)
Number |
Date |
Country |
1,297,561 |
May 1962 |
FR |
1,427,102 |
Dec 1965 |
FR |
Continuations (1)
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Number |
Date |
Country |
Parent |
428805 |
Dec 1973 |
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